The Urban Astronomer

Auriga and Capella: the Galactic Anticenter

2012-02-09T18:36:00.000-08:00

High overhead in the winter sky is the distinctive constellation Auriga the Charioteer. This is a bright constellation, visible even with city lights, punctuated by the 6th brightest star in the night sky, Capella. To the casual viewer, Auriga appears to be a pentagon in the sky, and in winter it is nearly directly overhead as night sets in. Depending upon the source, the constellation Auriga is described as the actual Charioteer holding a goat, or just the shape of his pointed helmet. The star name Capella is in fact Latin for 'small goat.'

Auriga has the distinction of being located in the direction of the Galactic Anticenter. What is an anticenter? It is the point in the night sky that is opposite the Galactic Center, of course :-) The center of the Milky Way Galaxy is located in the direction of the constellation Sagittarius, a dominant summertime constellation. So not surprising, in the winter time when we are looking the 'other direction' in the sky, we find ourselves staring out into space directly out of our Milky Way Galaxy.

The bright star Capella is relatively close to Earth, 42 light years away. It shines brightly in the winter sky, making Auriga easy to locate. A fascinating fact is that the star Capella is not one star, but a four-star system made up of two binary stars. That means, that the four stars are broken into two pairs of binary star systems. Two of them are big stars, 10 times the size of our Sun. The other two are quite small and faint, so when you see Capella you are primarily seeing the two bigger stars. Some binary star systems can be seen as separate stars in small telescopes or binoculars, but the two bigger stars in the Capella system are too close to see as separate objects.

Try to locate Auriga and Capella tonight and savor the fact that you are staring out of the Milky Way into the vastness of space far away from our home galaxy.

Resources for Urban Astronomers

2012-01-30T12:46:00.000-08:00

Over the past years in this blog, I have focused on information and news that can be used by city dwellers, guiding them to find interesting happenings in the night sky that are generally visible in light-polluted skies. I also have focused on San Francisco and West Coast US-based events such as eclipses. In addition to my own posts, I recommend a number of other astronomy sites with helpful information along the same lines, for the casual and amateur astronomer who wants to enjoy the night sky and learn something new about the universe.

Lately, I have been particularly fond of the Astronomy Picture of the Day, always bringing a fantastic new image to light, and the website Spaceweather.com, with interesting news focused on our Sun and the local region of our Solar System with updates on Near Earth Objects. As we approach a solar maximum over the next 18 months, I find Spaceweather.com full of exciting updates about aurorae and sunspots. Sky & Telescope Magazine has been a mainstay for me for years, and the website always includes the latest things to see in the night sky. I often reference images from the Sky & Telescope feature "This Week's Sky at a Glance." And I am enjoying the very interesting posts on the EarthSky blog, such as this great article on "10 Things You May Not Know About Stars."

I hope that you can find a lot of interesting reading and enjoy new perspectives on astronomy. And check in regularly for another post from me (about once a week) with my own musings on the joys of the night sky. I wish you clear skies and happy viewing!

Brilliant Venus

2012-01-22T22:59:00.000-08:00

Venus is growing brighter in the west each evening, a brilliant evening 'star' that commands your attention as you see the sunset sky darkening. I enjoy the game of finding Venus right after sunset, particularly from Ocean Beach not far from my home in San Francisco. If you have a good western horizon, Venus is well-placed above and to the left of the point of sunset. I find that just a few minutes after the sun has set, I can often find Venus, knowing that this time of year, the Moon and planets that are in the west shortly after sunset are, in fact, nearly 'above' the Sun since the path of these objects (the Ecliptic) is at a wide angle above the horizon. The image showing the position of the Moon and Venus on January 24, 25 and 26 gives you a sense of how great the angle of the Ecliptic is in the winter.

You can use this concept to help you find Venus after sunset, and see just how many minutes after the sun sets that you can spot that shimmering point of light we call our sister planet.

Image courtesy of Sky & Telescope Magazine.

Planets wandering through the Zodiac

2012-01-13T08:20:00.000-08:00

I've been fascinated by the movement of planets through the zodiac lately, showing this to guests at star parties and when I give talks at the California Academy of Sciences. Jupiter, being the dominant planet in the evening sky, brings my attention to the constellation Aries, which from an urban setting is two somewhat-bright stars paired next to blazing Jupiter. Following the ecliptic toward the east, you find a series of beautiful and bright constellations including Taurus, Gemini and Leo. By the time Leo is rising in the late evening, Mars rises with it, a distinctive orange-red color in contrast to the white and blue-white stars of Leo. By early morning when I first look outside, Virgo has risen, and along with it, Saturn.

Jupiter has a wonderful pattern of travel through the zodiac, moving one 'sign' per year as we observe it in its 12-year long journey around the Sun, seeing the slowly changing backdrop of stars along the ecliptic. By stark contrast, Mars flits rapidly from one constellation to the next, out of Leo and into Virgo in the coming weeks. And by contrast in the other way, Saturn lumbers along gradually changing zodiac position every 2 1/2 years, moving from Virgo at present to Libra in 2014.

EarthSky has a nice writeup on seeing all 5 visible planets in January. Enjoy the month and get outside if it's not too cold. As for me, I've been entranced by the clear nights here in San Francisco and look forward to the ongoing winter skies and the bold bright planets that punctuate the view.

Image courtesy Sky and Telescope.

Quadrantid Meteor Shower 2012 - peaks January 3-4

2011-12-30T10:05:00.000-08:00

The annual Quadrantid Meteor Shower peaks on January 3rd and 4th, with the possibility to deliver a great show for viewers across North America. The Moon will interfere in the early stages of viewing, but despite that, the shower should be a good one.

Meteor showers typically are strongest after midnight, when the Earth's 'front face' is moving directly into the meteor stream as the Earth moves in its orbit around the Sun. In addition, many meteor showers have a peak where the meteor stream is strongest. This year, North America is well positioned for the Quadrantid peak. For those of us on the west coast of the US, the peak should start around 11:00 pm on Tuesday January 3rd, and continue into the morning hours of Wednesday the 4th. You can read more about the meteor shower peak in an excellent article from the American Meteor Society. The Quadrantid 'radiant' is near the handle of the Big Dipper, which will be high in the sky in the morning hours.

Viewing the shower is easy. From 11:00 pm until 2:00 am (west coast time), face east as the radiant rises and climbs into the night sky. Later in the night, after 2:00 am, the Moon will be low and then set, and the best view will be directly overhead, ideally lying on your back in a dark location with a sleeping bag and warm clothing - it will be cold! In San Francisco, I find that I can see many meteor showers from my own backyard, despite being in a big city. The two important things to do are (a) find a location where streetlights and houselights are not shining in your eyes, and (b) allow for 10-15 minutes to fully dark-adapt to the night sky, and then you can expect to see meteors. If you just look outside for 1 or 2 minutes and don't see any, you should not be surprised. Meteor viewing requires patience and a little bit of planning. But the investment of time is worth it, because meteors are such beautiful cosmic things. I wish you clear skies and good viewing!

Image courtesy EarthSky.

A Beautiful Evening Pairing of the Moon and Venus

2011-12-25T11:15:00.000-08:00

The young crescent Moon will be paired up with the brilliant evening "star" Venus on Monday evening, creating a stunning visual in the sunset sky. The monthly cycle of the Moon always brings beautiful patterns as the daily travel of the Moon along the ecliptic brings it near to other objects. But when the Moon is paired with Venus, the next-brightest object in the sky, the view is riveting, especially when we have clear skies and a view to the west. I saw a similar pairing last month while traveling in Southern California, a magnificent Moon-Venus pairing in the glow of sunset to the west while out walking in the warm November air. This time, I'll be watching from the cool coast of San Francisco, but the view should be no less impressive. If skies permit, look west and enjoy this spectacle, all the more impressive if you view through binoculars or a telescope.

As the Moon passes through the Zodiac constellation Capricorn, it will also pass near Neptune on the 27th, then onward along the ecliptic into Aquarius and near Uranus on the 29th, heading toward a fly-by of Jupiter in Aries on January 1st. You'll need a telescope to see Neptune and Uranus, but not Jupiter, the other dominant object in our night sky right now.

Image courtesy Sky & Telescope Magazine.

The Longest Night and the Early Morning Darkness

2011-12-20T22:51:00.000-08:00

Winter Solstice brings us a long night, but not the latest sunrise. That comes in a couple weeks, for reasons too complex to explain here. The advanced student can follow this link to the EarthSky blog, or this one to Astroprofs. With the late sunrise, around 7:20 am this week in San Francisco, we have plenty of darkness in the morning to see the waning crescent Moon pass by some very fine morning stars and by the planet Mercury.

Morning skies offer a particularly beautiful view of the heavens, as the atmosphere is generally calm and often the sky clears as moisture and dust settle. Some of the bright urban lights that were glowing in the evening are switched off late at night.

The Big Dipper is high in the north-east by early morning as winter starts, and the brilliant winter constellations and stars punctuate the view overhead and to the west.

Weekdays I don't usually have time for a full viewing session early in the morning, but that doesn't stop me from stepping outside for a brief look around the sky. Try this for yourself when you first get up. You'll be impressed with the view, even in a big city like San Francisco.

Image courtesy of Sky & Telescope.

Geminid Meteor Shower 2011

2011-12-13T18:08:00.000-08:00

The Geminids peak the nights of December 13th and 14th this year, one of the better meteor showers of the year. Unfortunately for 2011, most of the Geminids will be nearly invisible due to the very bright Moon that dominates the late night and early morning sky, when the Geminids are at their best.

The effect of a bright Moon on a meteor shower was vividly illustrated to me during the Total Lunar Eclipse a few days ago. I was at Ocean Beach on the west coast of San Francisco for the eclipse in the early morning hours. Facing west, Gemini was directly in front of us, dominating the western sky. As the brightness of the Moon faded, we began to notice meteors -- we were seeing some very early Geminid meteors, facing the radiant directly. I was very surprised at the stark contrast in meteor visibility from Full Moon before the eclipse started, to an ever-increasing amount of meteors over a very short period of time as the Moon, in effect, when through all of its phases in about 60 minutes. It reaffirms for me the huge difference a moonlit night makes when watching a meteor shower.

Although the meteors will be diminished for the Geminid Meteor Shower in 2011, I'll still take a look, since a big shower like this has plenty of bright meteors that pierce the night despite moonlight. If you want to read more about the Geminids, check out this interesting article about the Geminids radiant, from Earth Sky, from the LA Times, or this one from NASA Science News.

Image courtesy EarthSky.

Total Lunar Eclipse 2011 - in San Francisco

2011-12-06T13:59:00.001-08:00

Saturday morning, we will witness a Total Lunar Eclipse visible from western North America and regions across the Pacific Ocean. In San Francisco, we will have a dramatic early morning spectacle of the fully eclipsed Moon setting on the Pacific just as dawn breaks. As with any total lunar eclipse, the Moon's surface will be completely covered by the dark 'umbral' shadow of the Earth, but it will remain visible, taking on an eerie appearance of rusty red, or deep grey, or a mix of colors. Every eclipse is a little bit different, so we wait in anticipation to see what happens Saturday morning.

The circumstances of this eclipse are outlined in detail in this informative Sky & Telescope article, and this excellent NASA Science News article.

The timeline for San Francisco (and the entire pacific time zone) are: start of eclipse at 4:45 am, start of totality at 6:05 am, and end of totality at 6:57 am. The glow of the dawn sky will emerge in the eastern sky shortly after 6:00 am, so the Moon will be in total eclipse as the sky begins to brighten, and by the time the Moon exits the total phase, the sky will be fully lit in advance of the sunrise at 7:13 am.

What does all this mean to the casual viewer? You will experience the best views and the most drama from 4:45 am until 6:30 am, when the Moon gradually changes from full to completely eclipsed, and the skies are dark enough to appreciate the beauty and subtlety of the lighting and color of the lunar surface. And as the Moon's brightness is attenuated as the Earth's shadow creeps across the surface, the backdrop of stars will begin to shine more brightly by contrast, revealing the wonderful winter sky at its best, with the constellations Taurus, Orion and Auriga around the Moon, and some of the most beautiful, bright stars in the entire night sky punctuating the skyscape.

I welcome the public to stop by Ocean Beach on the west coast of San Francisco for an early-morning star party, where I and others from the San Francisco Amateur Astronomers (SFAA) will have telescopes set up for public viewing. We will set up at the beachwalk just across from the Beach Chalet restaurant on Great Highway, starting around 4:30 am. But heed the advice of Deborah Byrd in this EarthSky article, and wear very warm clothes. You'll be glad you did, as the winter chill is quite intense just before sunrise.

Viewing all 5 Visible Planets in one night

2011-11-30T17:03:00.000-08:00

As the nights grow longer and the skies darker, we have the chance for the next few weeks to see all five planets visible to the naked eye in a single night. Of course, there are seven planets in our Solar System (not including Earth), but two (Uranus and Neptune) are just too faint to see without optical aid. However, the rest (Mercury, Venus, Mars, Jupiter and Saturn) are spread around the entire sky, adding a lot of brightness to our already-shiny Autumn and Winter skies. This article in the science blog EarthSky is an excellent guide to help you find each planet. Of course, to find Jupiter and Venus you need little guidance because they are so bright, but Mercury, Saturn and Mars will be easier to find with some assistance from a sky map.

And if you are ready to look deeper and see all 7 in one night, here is a chart to guide you to Uranus and Neptune. They are both just west of Jupiter, in the constellations Pisces and Aquarius.

Image courtesy NASA.

Saturn Returns

2011-11-20T09:36:00.001-08:00

Saturn has returned to the morning sky, rising higher each day shining in the east before sunrise. It is near the bright blue giant star Spica, in the constellation Virgo, and this week is graced by a visit from the Moon, creating a beautiful grouping on the morning of November 22nd.

Saturn and Spica are an interesting pair to compare. They are a contrast in color, with Spica shining a deep blue, and Saturn with a yellow-white tinge. Spica is 260 light years away, distant compared to many other bright stars in the evening sky, but being a giant star, it emits enough light to be the 15th brightest star in our night sky. Saturn is 80 light minutes away, a giant planet by Solar System standards, but due to its distance it never shines as bright as other Solar System objects such as Venus and Jupiter. But Saturn still captivates all who see it through a telescope because of its impressive ring system, making it a welcome target for any star gazer.

Image courtesy Sky & Telescope Magazine

Leonid Meteor Shower 2011

2011-11-15T21:27:00.001-08:00

The Leonid Meteor Shower peaks on November 17th, bringing fast meteors to the late night sky. This shower is generally a good one for stargazers, but the glare of the waning Moon will hide some of the fainter meteors. Nonetheless, a meteor shower brings all kinds of meteors, faint and bright, long-tailed streaks and short blips of light, so with some commitment and a dark sky, you will be rewarded with at least a few good meteors if you take some time to look.

Get a sleeping bag, comfortable chair or pad, and enjoy the sight late on the night of Thursday 17th into the morning of the 18th. The radiant of this eclipse, the constellation Leo the Lion, is above the horizon after 9 pm and high in the sky after midnight, and although the namesake constellation appears to be the "source" of the meteors, in fact the Leonids will be visible in every direction, so the best view is to simply look straight overhead. I'll give it a go from my backyard here in San Francisco, a nice way to close out my birthday :-)

This excellent article in The Universe Today provides a lot more backgound information, as does this article from National Geographic.

Image courtesy Stardate.org.

An Asteroid Makes a Near-Earth Approach - YU55

2011-11-06T23:21:00.000-08:00

We have a special event coming our way, literally. An asteroid by the name of YU55 will speed near Earth on Tuesday 8th, perhaps even becoming visible for those with a good telescope and a clear view to the west. David Perlman's article in the San Francisco Chronicle includes some very helpful information how to find this, as does Kelly Beatty's writeup in Sky and Telescope.

Track of asteroid YU55

This is a fairly rare fly-by of an asteroid. There are 1000s of "Near Earth Objects" (NEOs) being tracked. Tiny objects like meteors are commonplace, impacting Earth daily, and causing no harm as they burn up in the atmosphere. But the NEOs are larger, potentially causing considerably greater harm if they were to collide with Earth. Happily, all NEOs that are being tracked at this time are not on a collision course with us. YU55 will pass quite close by cosmic measures, within the orbit of the Moon. At 1/4 mile in size, an impact by YU55 would cause major damage on Earth, but we need not worry. And the next close fly-by of an asteroid is not expected until 2028, with a similar 'miss by a mile' outcome. Sleep well!

Jupiter at Opposition -- closest approach for 2011

2011-10-27T17:19:00.000-07:00

The Autumn evening sky is being dominated by one bright, shiny object: the planet Jupiter, which will be a highlight for several months in our skies. On October 28th, Jupiter reaches "opposition" in which it is in a line with the Earth and Sun (and no, that is not what has been causing the recent earthquakes in the San Francisco Bay Area!).

Image Courtesy NASA

When Earth travels around in its orbit, approximately every 13 months we have a close encounter with Jupiter. When we do, the gas giant looks impressive with or without a telescope. Without a telescope, Jupiter is extremely bright, easily 50 times brighter than the brightest stars in the sky right now. It rises due East just after sunset, and remains visible the entire night. Through a small amateur telescope, Jupiter is a fine target, easy to locate and impressive with bands across its disk and the four Galilean moons shining brightly. Now is the time to get out a telescope or binoculars and share the brilliance of Jupiter with someone.

KFOG Broadcast - October 25, 2011

2011-10-25T10:12:00.000-07:00

I was a guest on a live broadcast with the KFOG Morning Show today, talking about Jupiter, things to see in the Autumn night sky, the Pleiades, meteor showers, and the Bay Area Science Festival. The DJs on the Morning Show are an interesting group, and the conversation is always lively. Click here to listen.

The Changing Sky: Mira, a Variable Star

2011-10-22T22:41:00.000-07:00

When observing the night sky, I enjoy the slow changes of the seasons and the stars as they arrive into the evening sky. The Moon and planets change their positions regularly, sometimes quite quickly. And transient events such as meteor showers and eclipses bring some drama to the sky. But the backdrop of stars is supposed to be constant and unchanging. And that brings me to the motivator for this blog post, the variable star Mira.

Stars have billion-year life cycles, so for us to witness a star's brightness changing over days and weeks is a rare thing. Astronomers study this special class of stars that regularly vary in brightness, and there is an association, the American Association of Variable Star Observers (AAVSO) that collaborate on research in this field. There's even a cool iPhone app that developer John Rachlin introduced me to. It's called Variable Stars, and it is free.

Mira is a well known variable star, and lately it has been changing its brightness very fast and over an extreme range, so that this star that is normally invisible to the naked eye is suddenly visible in the evening sky. I stepped outside this evening and found it near Jupiter, just a "thumb and a little finger away" as described by astronomy writer Tony Flanders in this Sky & Telescope article. I'm pleased to have found this special star that is now 1000s of times brighter than usual. If you feel up for a challenge, try to find it tonight.

Image courtesy of Sky & Telescope Magazine.

Orionid Meteor Shower 2011

2011-10-20T18:38:00.000-07:00

The Orionid Meteor Shower peaks for the next two mornings, October 21 and 22, as the Earth passes through a debris stream left by Halley's Comet. Like all annual meteor showers, the Orionids occur at the same time each year because the Earth, in its 365-day trip around the Sun, passes through areas of increased debris, leading to a much more focused period of time with meteors flying into Earth's atmosphere and creating those beautiful streaks of light that magically light the sky for a moment and then vanish without a trace.

The name Orionids tells us that the meteors in this shower appear to emanate from the constellation Orion, the beautiful winter sky constellation. But like the best meteors in any shower, you won't see Orion until after midnight as it rises out of the east. Meteor showers are best observed between midnight and sunrise, when you are viewing meteors entering our atmosphere on the 'front face' of the Earth. Given that sunrise is quite late this time of year, take advantage of that and get up just ahead of dawn's light, around 6:15 in the San Francisco Bay Area.

Image courtesy of Earth Sky.

Brilliant Moon and Jupiter

2011-10-12T06:28:00.000-07:00

The Full Moon dominates the night sky this week, lighting the Autumn landscape and making its presence known as the soft grey glow of moonlight washes out all but the brightest stars in the sky. But even as the stars take a back seat in the night sky, the giant planet Jupiter shines steadily next to the Moon, undiminished by the intense glow of our nearest celestial neighbor.

Jupiter is nearing "opposition" in which it is at its closest approach to Earth for 2011. That means that it is also at its brightest, outshining all other celestial bodies in the night sky right now, except the Moon. For the next few nights as the Hunter's Moon passes near Jupiter, your attention will be drawn to the dazzling brightness of the largest planet in the Solar System. And once the Moon has moved into Last Quarter phase next week, Jupiter will remain steadfast in the evening sky, waiting for you to find it in binoculars or a small telescope. Take a moment and look up close if you have not seen Jupiter up-close. It's a worthy (and easy) target.

Image courtesy of Sky & Telescope Magazine.

Get Involved: Star Parties and Astronomy Lectures

2011-10-09T21:27:00.000-07:00

There are many ways to get involved with astronomy. No matter where you live, you can find local clubs and events using the Night Sky Network website. Just about anywhere you go, you'll find a friendly astronomy club ready to welcome a new guest or member.

In the San Francisco Bay Area, we have a wealth of resources. As a member of the San Francisco Amateur Astronomers (SFAA), I always recommend the monthly lectures at the Randall Museum in the City, open at no charge to the public (next lecture on October 19th). The California Academy of Sciences has an excellent lecture series, the Benjamin Dean Lecture Series, focused on astronomy topics (next lecture on October 17th). And in the greater bay area, you'll find things happening at The Lawrence Hall of Science in Berkeley, the Chabot Space and Science Center in Oakland, Foothill College (lead by award-winning Professor Andrew Fraknoi) in Los Altos Hills, and more.

I take part in a few specific events. One of my favorite places to show off the night sky is at the weekly NightLife event at the Cal Academy in Golden Gate Park, every Thursday night. When the skies are clear, I can be found on the Living Roof showing off the skies with a trusty laser pointer, alongside Academy staff with telescopes pointing at the Moon, Jupiter, or other objects of interest. It is an excellent place to have fun and learn some new things about the night sky.

On November 5th, I'll be working with Tucker Hiatt of Wonderfest during the Bay Area Science Festival with a star party on Mt. Tamalpais in Marin County. We're calling the event "Nekkid-Eye Nightscape," and it will follow a lecture called The Milky Way as Dark Matter Laboratory. Tucker and I will give an introduction to the night sky, showcasing the best and the brightest objects in the Autumn Sky. After the lectures, the SFAA will be there with wonderful telescopes to show off the night sky up-close and personal.

I hope to see you at an event sometime soon!

Mars passes through a star cluster, the Beehive

2011-09-30T16:53:00.000-07:00

Our fellow planets in the Solar System are on the go, always wandering from place to place in the sky. The rocky planets (Mercury, Venus, Mars) move quickly, due to their closer proximity to the Sun, and their motion from day to day can be noticeable to the naked eye. The gas giant planets (Jupiter, Saturn, Uranus, Neptune) move more gradually but are nonetheless regularly moving against the backdrop of stars.

Mars, being our 2nd-closest Solar System neighbor, can appear to move quite considerably against the backdrop of stars from one night to the next. This week, it will pass through the constellation Cancer and in doing so, travel through one of the most well-known star clusters in the heavens, the Beehive Cluster. This will be a fine site even in city skies, but you will need binoculars to truly appreciate the view. Use the diagram to find this spectacle in the early morning sky, looking due east (just as I can see when I walk out my front door in the morning). Enjoy!

Image courtesy of Sky & Telescope Magazine.

Observing Twilight into Dusk

2011-09-27T08:52:00.000-07:00

The minutes after sunset are some of the most beautiful, as the last rays of sunlight have disappeared and the sky begins its daily transition from bright blue to dark night. Looking west after sunset in the early days of Fall, you quickly find Arcturus shining due west, at first looking almost like an airplane that is moving very slowly. But soon you realize that this is a star, the third-brightest in the heavens. It is bright enough to shine clearly through the glow of twilight. The colors of the sky are changing rapidly during twilight, and the brightest stars soon emerge. In late September, you can easily find the fifth-brightest star in the heavens, Vega, directly overhead, guiding you to its neighbors Deneb and Altair in the Summer Triangle. And looking back toward the western horizon where Arcturus is shining, you can soon find the red supergiant star Antares shining low to the left (south-west) of Arcturus.

Later this week, the young Moon arrives in the twilight sky and passes near Antares. Find a nice western horizon, get comfortable, and enjoy the evening show that is pleasant, relaxing and beautiful to see.

Image courtesy of Sky & Telescope Magazine.

Autumnal Equinox: what do you see?

2011-09-19T14:48:00.000-07:00

Friday September 23rd is the start of Fall here in the Northern Hemisphere, an event that has a specific moment, in this case 2:05 am on the West Coast. What happens at this moment? Can you 'see' an Equinox?

The two Solstices of the year, in December and June, get much more fanfare because they mark more dramatic transitions, both in the weather and in the slow change of the seasons. The longest day and shortest day of each year are much easier to understand. But the balance points in the equation of Earth's orbit, the Equinoxes, get much less attention because there is much less drama. But for me, there is a lot going on. From an observational point of view, there are three things to look for.

1. Sunrise is precisely due East and Sunset precisely due West, the two days of the year this happens.

2. The Sun is above the horizon 12 hours and below the horizon 12 hours (give or take a few minutes owing to the bending of light around the horizon as experienced at Sunrises and Sunsets).

3. The Sun's height in the sky at local noon, as measured in degrees above the southern horizon, is 90 degrees minus your latitude on Earth. For example, in San Francisco, we are about 38 degrees north of the equator, so the Sun's height at local noon is 90 - 38, or 52 degrees above the horizon.

There is a fourth, more subtle effect that happens around the time of the Equinox. The length of the day is changing most rapidly around this time. From the Summer Solstice to the Winter Solstice, the length of the day is continually reducing. On the Equinox, it is 12 hours, but from one day to the next the length changes about 2 1/2 minutes, around 16 minutes during the full week. That is noticeable, and if you get up at the same time each day, you are certainly aware of the changing light of the morning (or lack of light at this point in time).

The combination of the Earth's annual circuit around the Sun, the tilt of the Earth's axis, and the slightly eccentric orbit of the Earth around the Sun all contribute to very interesting effects that are most pronounced around the interesting transition points of Equinoxes and Solstices. Take a moment this Friday to appreciate what you are observing in the sky around you.

KFOG Podcast - Sep 16, 2011

2011-09-16T10:47:00.000-07:00

Today's discussion with KFOG's Irish Greg features (a) the Milky Way in the Autumn Sky, (b) Fireball across Southern California, (c) new planets being discovered, and (d) the Supernova in the Pinwheel Galaxy. As always, it's good fun and in exactly 8 minutes, you'll be a more informed citizen scientist. Click here to listen.

Seeing the Supernova in the Pinwheel Galaxy

2011-09-08T08:58:00.000-07:00

This week we can witness, first hand, a supernova that was just discovered in the Pinwheel Galaxy. A supernova is an explosion that marks the end of the life of a star, and usually these fiery events emit a great deal of light, brighter than anything else in the region for a short period of time. In this case, the star was a white dwarf of similar mass to our own Sun, but located 21 million light years away in a relatively-close galaxy. It is brightening and will be visible at its peak this weekend. However, you will still need patience and some kind of optical aid (telescope or binoculars) to see this.

The Pinwheel Galaxy (also known as M101) is located near the Big Dipper, quite high in the sky after sunset, so use the handle of the Big Dipper to help you located the Pinwheel Galaxy. Supernova discoverer Peter Nugent of Berkeley explains how to find the Supernova in this short video. To set expectations, the supernova will be a bright spot of light, similar to a star, so don't expect to see a vast region of glowing gas and colors, but nonetheless, you can be assured that the light you are seeing has been traveling for 21 million years directly from one of the most violent, cataclysmic places in our universe, at a moment just after a star's life has ended and new matter has been created. That is a good thought to ponder as you search for the supernova.

Good luck, and leave a message if you find it!

Big Astronomy Events in 2011 and 2012

2011-08-31T22:14:00.000-07:00

Much of the time, I enjoy astronomy as a day-to-day hobby, taking in the sky often and enjoying the slowly changing view of the heavens. Sometimes, however, big events come along and obligate the observer to be present at a specific moment in time -- and also have the good luck of clear skies. We have a three such events in the coming year, and the San Francisco Bay Area is a good base from which to see these events.

1. Total Lunar Eclipse, December 10th, 2011.

This Lunar Eclipse will peak on Saturday morning, December 10th, just before sunrise here in San Francisco, meaning that if the skies are clear, the best view will be at the coast, where the Full Moon will be entering Total Eclipse just as it is setting over the Pacific. This will be impressive!

2. Annular Eclipse of the Sun, May 20th, 2012.

An Annular Eclipse, also called a "Ring of Fire" eclipse, happens when the Moon's disk fits "inside" the disk of the Sun, creating a ring of sunlight in the sky. It's not the same as a Total Solar Eclipse, but still a beautiful natural phenomena, one worth a trip to Northern California to see. The viewing path can be seen on the map in this link, and will pass near Redding and Mt. Shasta in Northern California. I'll be organizing a road trip with the San Francisco Amateur Astronomers (SFAA) to see this spectacle.

3. Transit of Venus, June 6, 2012.

A transit of a planet in front of the Sun is a rare and unusual event. This is one of a pair of transits of Venus, the first of which occurred in 2004, paired with this one in 2012. Then we have a 100-year gap until the next pair of transits of Venus. It will be a daytime event, of course, because we are going to see the tiny disk of Venus cross directly over the Sun's disk.

- - - - - - - - - - - -

I'll write about each of these events as the time draws nearer, so for now the main thing is to mark your calendar and do a bit of background reading by following the links in this blog post.

Image courtesy of NASA.

Seeing the Milky Way in City Skies

2011-08-21T07:43:00.000-07:00

Summers bring pleasant viewing and a wealth of richness in the heavens. As the Summer Triangle rises and dominates the night sky, two of my favorite Zodiac constellations, Scorpius and Sagittarius, are visible deep in the southern sky. These big, bold constellations combine with the Summer Triangle to guide the urban star-gazer to the Milky Way.

For anyone who has seen the spectacle of the Milky Way in dark skies, you know just how profound this band of light looks as we view our own galaxy from within. And I know how disappointing it is after a few days in dark skies, to return to the city and realize that the beauty of the Milky Way is missing. But don't despair, for even in urban settings, you can still see many of the wonders of the Milky Way. To do this, you need to use a telescope or binoculars. Using Scorpius and Sagittarius as your anchor on the southern horizon, and the Summer Triangle high above, point the telescope or binoculars into the sky and move slowly from the south slowly overhead. You are looking into the Milky Way, and with the magnification and light-gathering of a telescope or binoculars, you cut through the glow of the city lights and enhance the light from space. And that will be a rewarding moment under the sky. No need for a fancy star chart or an iPhone app. All you need is a sense of wonder and a comfortable chair.

Perseid Meteor Shower 2011

2011-08-06T18:53:00.000-07:00

Every Summer, the Perseid Meteor Shower raises the hopes of those interested in the night sky. Being one of the biggest meteor showers of the year, coupled with the fact that it takes place in the middle of Summer, it's not surprising that many look forward to it. However, some of the best viewing of the Perseid Meteor Shower in 2011 will be washed out by the Full Moon which coincides with the peak of the shower on August 12th and 13th.

However, all is not lost. Meteor showers vary in the duration, some lasting only a day or two with a clear peak moment, while others are spread over a longer period of time. Luckily, the Perseids are a longer-duration meteor shower, starting in late July and continuing through mid-August. Although the best viewing is on August 13th, the rate of meteors is already dramatically increasing by August 9th, and at that point in time this year, the Moon will not completely wash away the meteors. In fact, the Moon will be setting in the early morning, giving the dedicated meteor chaser an hour or two to see some fine Perseids before the first light of dawn. So my advice is to look on this schedule:

Early morning Tuesday August 9th: From 1:30 until 5:00 am.

Early morning Wednesday August 10th: From 2:30 until 5:00 am.

Early morning Thursday August 11th: From 3:30 until 5:00 am.

Early morning Friday August 12th: From 4:30 to 5:00 am.

These times are for San Francisco. The start time depends upon when the Moon sets, a bit later each morning. The end time depends upon the time of your local sunrise which may vary based upon your location. Use this website to determine your local conditions. In San Francisco, sunrise is shortly after 6:00 am, so I recommend viewing until 5:00 am at which time the first light of dawn will begin to interfere with viewing of meteors.

As is the case with every meteor shower, you need to get yourself in as dark a location as you can. In a big city, that means away from streetlights and in a spot with a big view of the sky. The meteors will appear to emanate from the East, but they will cross the sky in all directions, so your best view is lying on your back looking up. Get some blankets, stay warm and enjoy.

Image courtesy National Geographic.

Daytime Astronomy: Sunspots

2011-07-26T12:21:00.000-07:00

Summer nights are short, making it more challenging to enjoy the night sky. But days are long, and the Sun often provides some fireworks to make things interesting. Right now, the Sun is moving into a period of maximum solar activity. Maximum solar activity comes as part of an 11 year cycle in which we observe peaks and valleys in the number and size of Sunspots, with the next peak in 2012.

Sunspots are areas on the surface of the Sun where magnetic fields have caused a disturbance in the normal flow of heat from the core of the Sun , and the areas appear black through Earth-based solar telescopes. These areas are "cooler" than the surrounding surface of the Sun (I'm not sure if the term "cooler" applies to the surface of a 10,000 degree star!), which means that Sunspots check in at about 5000 degrees. With a well filtered telescope, the areas look black by contrast to the extremely bright solar surface, known as the Photosphere. It's one of nature's truly fascinating phenomenon, and a wonderful thing to see directly through a telescope.

Our eyes are sensitive light sensors, and are completely overwhelmed when you look directly at the Sun. The heat from the intense radiation of the Sun can cause blindness in a matter of seconds. Fortunately we instinctly look away from the Sun and preserve our vision naturally. Experienced astronomers, however, can safely use solar filters on telescopes to cut the brightness of the Sun to the brightness of the Full Moon, and hence use a standard telescope with a filter to enable daytime astronomy. In San Francisco, you sometimes find a Sidewalk Astronomer showing off the Sun during the day. With the increase in Sunspots during 2011 and into 2012, I'll be out on the sidewalk doing this from time to time, and even if you don't have access to a solar telescope, you can check out Sunspots on the solar surface daily at the excellent website SpaceWeather.com. This website has some very amazing images of the Sun and other space-related "weather" items.

Remember: only view the Sun with properly designed filtering intended for safe solar viewing.

Image courtesy of SpaceWeather.com.

One Year on Neptune

2011-07-16T15:15:00.000-07:00

We passed a landmark moment this month, the one-year anniversary of the discovery of the Blue Planet, Neptune -- one Neptunian-year, that is, which is 165 of our Earth-years. This gem of a planet is something that an urban astronomer has to work a bit harder to see, but once spotted it is a lovely blue point of light in the sky, a fine payoff for those with the persistence to track it down against the backdrop of stars in the heavens.

During its long trek around the Solar System, Neptune has periodic close encounters with other planets, as it did during the "Triple Conjunction of 2009" with Jupiter. However, this year it stands alone in the constellation Aquarius, more challenging to find because we don't get Jupiter as a beacon leading us to find the elusive blue planet. However, using this star chart, a pair of binoculars, a dark backyard location, and some patience, I am sure you can find it. I will be looking from time to time over the coming months as Neptune moves from the morning sky into the evening sky, scanning for its dim blue glow in the vastness of the night sky.

KFOG Podcast - July 8, 2011

2011-07-08T12:46:00.000-07:00

Today was the final launch of the Space Shuttle. KFOG's Irish Greg and I talk about this historic event, about the wonders of the Summer night sky, and about upcoming Star Parties in the San Francisco Bay Area. All in 5 minutes! Listen here.

Moon in Descent

2011-07-05T22:51:00.001-07:00

The Moon traces out a path across the sky that is slightly offset from the path of the planets and Sun (the well-known "ecliptic" path). The orbit of the Moon is inclined to the ecliptic by 6 degrees, meaning that at any given point in a month, the Moon might be found in the sky just at the ecliptic, or moving below the ecliptic (up to 6 degrees away from it), or above the ecliptic. As it travels in its 29 day journey around the Earth, the Moon passes through the ecliptic twice, once going down (descending node) and once going up (ascending node).

Since we just finished an Eclipse Season, the Moon's nodes are very near to the points in space where we have New Moon and Full Moon, enough that from the New Moon a few days ago, to the First Quarter Moon later this week, we see the Moon traveling past the descending node and moving well below the ecliptic. Visual proof of that this week comes in the form of Saturn and Spica (see image), both of which are nearly on the ecliptic. The daily change in location of the Moon shows us just where the Moon is in relation to the ecliptic, this week skirting just south (below) this imaginary line in space.

The Moon amid planets and star clusters

2011-06-26T18:36:00.000-07:00

The morning sky this week will be rich with easy-to-spot celestial objects in the hour before sunrise. Find a good view toward the eastern horizon and use binoculars to enhance the view of Venus, Mars, the waning crescent Moon and two of the finest star clusters in the sky, the Pleiades and Hyades. I am looking forward to it!

Get Involved: Public Nights at Observatories, Stargazing at the Libraries and Museums

2011-06-16T10:15:00.000-07:00

There are many ways to get involved with astronomy, and I want to provide some links to get you going places.

First, some places where I present astronomy. I am a regular at the California Academy of Sciences most Thursdays at their NightLife event. These are for adults-only (sorry, kids, they serve alcoholic beverages), and when the skies are clear, they have astronomers with telescopes trained on stars and planets, and me giving tours of the night sky. Stop by on a Thursday night and enjoy the Cal Academy, and journey up to the Living Roof for a personal tour from me.

I make special presentations for organizations around the Bay Area, this week at the Marina Public Library as part of the IMBIBE series of events being put on by the Friends of the San Francisco Public Library. Come join me Friday night, June 17th, to see our nearest star (with its fascinating Sunspots) up close, and when the skies turn dark, a close up view of other celestial highlights.

Local observatories and science museums hold regular astronomical viewing nearly every weekend. Chabot Space and Science Center has viewing on Friday and Saturday nights through their powerful telescopes. The Peninsula Astronomical Society hosts viewing at the Foothill College Observatory in Los Altos Friday nights. And the Lawrence Hall of Science has viewing on Saturdays. Finally, my own club, the San Francisco Amateur Astronomers, hosts a monthly Star Party at Mt. Tam in Marin, along with a lecture at the Mountain Theater. I often give tours of the night sky at the Mt. Tam star parties.

There's no excuse if you live in the Bay Area. And if you are not in the San Francisco Bay Area, check the Night Sky Network to find a club and activities near you.

The Very Long-lasting Total Lunar Eclipse of 2011

2011-06-12T14:38:00.001-07:00

On Wednesday June 15th, viewers in the eastern hemisphere will be treated to a very long-lasting Total Lunar Eclipse, a 100-minute marathon of an eclipse that will reveal the center of the Milky Way in the backdrop as the bright Moon is enveloped in the darkest part of Earth's shadow. Unfortunately for those of us on the other side of the Earth, including here in San Francisco, we will miss the entire eclipse. (But we will get a nice lunar eclipse later this year, on December 10th.)

As for June 15th, this particular Total Lunar Eclipse will be longer than most for two reasons, (a) the Moon passes nearly through the center of the Earth's shadow, and (b) the Moon is nearly at Apogee, when it is farthest from the Earth (and hence appears a bit smaller than usual and takes longer to pass through the Earth's shadow). For my colleagues in Germany, the Moon will rise already in mid-Eclipse, which is an outstanding sight that I have seen one time in the past. Moonrise will be at approximately 9:30 pm, and the Moon remains in total eclipse until approximately 11:00 pm. That would be something to enjoy from a spot with a good eastern horizon. For other locations around the world, use this chart from the NASA Eclipse Web Site to determine the timing for your location. I wish my friends on the other side of the world clear skies and happy viewing!

KFOG Podcast - June 10, 2011

2011-06-10T09:56:00.000-07:00

KFOG's Irish Greg and I talk about Saturn and a Double Star, the Big Dipper and asterisms, a fun event where I'll be showing off the night sky, observatories that have public viewing nights, and a massive solar flare. Listen here. A good time is guaranteed!

Double Star and Planetary Close Encounter: Porrima and Saturn

2011-06-09T10:58:00.000-07:00

Light-polluted skies allow us city dwellers to only see the brighter objects in the night sky. Luckily, there are plenty of bright objects to see, and for the next few weeks Saturn has a close-encounter with a fairly bright double star. It's time to get out your telescope and put it to work, for the reward will be worth it.

The double star, Porrima, is a double star system located about 40 light-years away, relatively close to the Sun in the grand scheme of things. The two stars orbit each other about every 170 years, and as they do so, the apparent distance that separates them changes (from our Earth-bound point of view). Right now, the two are well separated, meaning that with a telescope pointed at Saturn you will see the two stars as distinct objects. Only a few years ago, their alignment was such that you would have needed a very powerful telescope to see the two stars in the Porrima system as individual stars. Right now, if you put Saturn into view in a small to medium telescope, you will also get the Porrima system in your field of view as well.

The diagram (above) illustrates where to find Saturn and Porrima over the next few days, and this article from Space.com also provides insight and additional diagrams to help you see this sight.

So seize the moment and be an amateur astronomer for a night, making a fun discovery for yourself.

Twin Stars and Moon in the West

2011-06-03T17:49:00.000-07:00

As the days lengthen and the sky stays lit well into the evening, many familiar constellations are rapidly slipping out of view. The bright twin stars of Gemini, Castor and Pollux, are fading fast and will soon be gone from the night sky. Enjoy a few days of this sight, with the addition of a fine young Moon in the sunset sky this weekend.

Eclipse Season: Three Solar and Lunar Eclipses all in a row

2011-06-01T09:23:00.000-07:00

For most people it is a surprise to learn that Solar and Lunar eclipses are quite frequent events. Every six months we have an "Eclipse Season" in which we have two or sometimes three eclipses over the course of a few weeks, depending on the exact geometry of the Sun-Earth-Moon trio. June is one of these months, starting with a Partial Solar Eclipse (today), then a Total Lunar Eclipse mid-month, and finishing with a Partial Solar Eclipse (actually in July, but just hours after the end of June!).

Eclipses are indeed common for Planet Earth, but for a given fixed location on the planet, eclipses are less common. For example, the first eclipse (Solar) of June is visible only from the very far north regions of the planet. The Total Lunar Eclipse mid-June will be visible primarily in the eastern hemisphere, so for those of us in San Francisco, it will take place during the day when we cannot see the Moon. And the final (Solar) eclipse of this eclipse season will be visible only in a small region of the globe deep in the southern hemisphere.

Eclipses come in "seasons" because they can only happen when the Moon is precisely positioned to cast its shadow on the Earth, or when the Moon passes precisely through the Earth's shadow. As the Moon's orbit is not exactly aligned with the Earth's orbit, the two orbits (and shadows) come into alignment for a few weeks every six months. The rest of the time, the shadows of the Moon and Earth miss each other and we are eclipse-free!

Since eclipses are such dramatic events, when they are visible in your area, you should go out of your way to see them. For us in California, the next good eclipse will be a Total Lunar Eclipse on December 10th. More on that when the date draws nearer.

Meanwhile, if you want to know more about upcoming eclipses, visit the excellent on-line resource from NASA. The NASA Eclipse Web Site is filled with detailed information about solar and lunar eclipses, including maps, charts, and exact timing for each event. Another excellent resource is the EarthView Eclipse Network. The image (above) is courtesy of the EarthView Eclipse Network.

Planetary Lineup on May 21st

2011-05-16T21:32:00.000-07:00

With all of the talk about May 21st, I felt it would be helpful to guide observers to a genuine, heavenly lineup that will create a beautiful pattern in the morning sky on the 21st and 22nd. During the entire month of May, the four nearest planets to Earth have been creating a beautiful sight in the morning sky just ahead of sunrise. On May 21st and 22nd, Mars, Mercury and Venus form a compact cluster. Bright Venus is the "guide star" to help you find this grouping in the east. You will want to look about 30-45 minutes before sunrise, and you will need binoculars to see Mercury and Mars, but Venus will shine brightly despite the glare of the soon-to-be-rising Sun. Jupiter is also quite visible in the sky, but each day pulls away to the upper right (toward the south-east) a bit more from the other three planets. Note that the image of the view toward the east, which comes courtesy of Sky & Telescope Magazine, demonstrates that astronomers are confident we'll have something to see the morning of the 22nd!

Venus, Jupiter, Mars and Mercury in Conjunction

2011-05-06T20:00:00.000-07:00

Four of the five most-visible planets are bunched together in the morning sky, creating beautiful patterns along the eastern horizon at dawn for the next few weeks. Each day the four planets change slightly in position, with bright Venus guiding your eyes to the right spot on the horizon where you can see these four points of light. Use binoculars to find all four planets - Mercury and Mars are much fainter than Jupiter and Venus - and use this amazing animation on the Sky & Telescope website to find the exact pattern as it changes each day. In San Francisco, you will want to look for this between 5:00 and 5:30 am, before the glare of the sunrise washes out the view of the planets.

KFOG Podcast - May 6, 2011

2011-05-06T15:33:00.000-07:00

In today's podcast, KFOG's Irish Greg and I talk about the big planetary conjunction , how to find deep-space objects, upcoming astronomy lectures and star parties on Mt. Tam, and the likelihood of astronomical chaos on May 21st :-) Listen here!

Eta Aquarid Meteor Shower 2011

2011-05-04T19:47:00.000-07:00

Meteors are wonderful to see, arriving unannounced and fleeting in an instant across the sky, obligating the hopeful viewer to pay attention or miss this spectacle of the heavens. On any given night if you simply are out viewing the skies, you will probably see one or two, but throughout the year there are special times when the Earth's orbit takes us through a region of space dust, creating meteor showers, in which the intensity and regularity of meteors increases dramatically.

The Eta Aquarid meteor shower peaks Thursday night, the night of May 5th into the morning of May 6th. This is not the biggest meteor shower of the year, but it certainly is interesting because it is caused by small bits of debris from the trail of Halley's Comet, the famous comet that orbits the Sun and is visible from Earth every 76 years. Comets leave small trails of debris in their wake, and comets that have orbits that intersect the orbit of Earth around the Sun create our annual meteor showers. So if you see an Eta Aquarid meteor tonight, you'll know it was once part of Halley's Comet, having been stripped away by the heating of the Sun on some past fly-by of Earth.

To see this shower, as is the case for all meteor showers, you need a dark location (even a backyard shielded from streetlights in the city will do), warm blankets, a recliner chair or a patch of grass to lie on, a big view of the sky, and patience. The name of this shower is based on Aquarius (the constellation) where the meteors appear to originate from, but they are visible all over the sky. Best viewing for this shower is early morning. The dawn sky will start to brighten around 5:00 am, so you will need to start early Friday morning if you want to see these. Have fun!

The Last Vestiges of the Winter Sky

2011-05-02T07:43:00.001-07:00

The young Moon graces the last vestiges of the winter sky this week, creating a beautiful pattern in the west for several evenings in a row. The big, bold constellations of winter including Orion, Taurus and Canis Major, and the very distinctive asterism the Winter Triangle are sinking lower each evening into the glow of the sunset sky, and on May 4th, 5th and 6th the Moon enters the picture to create a spectacular evening picture.

I have been doing Star Parties and outdoor presentations on astronomy the last few weeks, and the change from week to week has been dramatic. There is a natural change to the sky each evening, as the constellations and bright stars along the celestial equator and zodiac (ecliptic) move approximately 1 degree westward toward the sunset. At the same time, the length of each day is growing, meaning that these great winter constellations are disappearing rapidly into the glare of sunset. But there is nothing to worry about -- they will make their way around the sky to rejoin the view in the early morning, and continue the great ritual of the sky changing slowly from one season to the next.

Viewing Gemini and a Deep Space Gem, M35

2011-04-25T13:44:00.000-07:00

Spring skies are dominated by an array of bright stars and distinctive constellations. In April and May, the zodiac constellation Gemini dominates the view to the west, gracing the sky with the twin stars Castor and Pollux, and guiding the curious observer toward a gem in the river of the Milky Way, which flows across the legs of the twin brothers.

The star pattern of Gemini is of the brothers Castor and Pollux standing side by side. The bright twin stars represent the heads of the twins, and the stars that are below Castor and Pollux trace out their bodies, arms, legs and even a foot. An advantage to viewing Gemini in the Spring is that the brothers are standing upright and are easy to see, whereas in other times of the year when Gemini is visible, the brothers are not in an easy-to-spot orientation, or are directly overhead, a difficult thing to see.

If you have binoculars, you can try to spot a very faint but beautiful star cluster called M35 near the foot of Castor, the twin on the right-hand side of the pair. You will need a star chart (click on the image above, or try this fine star chart) to locate this small circle of stars but if you have patience and a dark viewing location, you will know you have found it because M35 seems to glow in the view of your binoculars compared to the stars around it. The stars in M35 are quite distant, nearly 3000 light-years away (but still within the Milky Way galaxy).

Happy viewing, and good luck with M35!

Five Weeks of Planets in Conjunction

2011-04-17T17:43:00.000-07:00

We are entering a period of time in which several planets are going to be in close proximity to each other, creating special alignments called "conjunctions." Mars, Mercury, Jupiter and Venus are all occupying the same region of the sky from our Earth-bound point of view, and as these planets and our own planet are all in motion around the Sun, the pattern we see in the sky changes quite a bit from one night to the next. At this time, all of these planets are emerging from the glare of the brightening dawn sky, appearing in the east just minutes before sunrise. Therefore, the initial conjunction on April 19th is best visible with the aid of binoculars. But this is just the start of a five week period in which these planets move very close to one another, creating a beautiful series of patterns for the early morning observer.

Our planet moves nearly 2 million miles per day in its orbit around the Sun. The planets are also moving at high speed around the Sun in their respective orbits. Mercury and Venus move the fastest relative to Earth, and because of their unique position inside the orbit of Earth, we see their changing locations in the early morning just before sunrise, or in the evening just after sunset. The other planets, including Mars and Jupiter for the next few weeks, move more slowly from our point of view and move more steadily from east to west from one morning to the next. I'll be posting a regular series of updates over the next month as the various conjunctions come and go. The important thing for the observer is to find a good eastern horizon, dust off the binoculars, and be ready to get up just before sunrise to see these cosmic alignments.

The Moon and two Star Clusters: Pleiades and Hyades

2011-04-04T10:44:00.000-07:00

The Moon graces the last vestiges of the winter sky this week, as the waxing Moon splits two of the prettiest star clusters, the Pleiades and the Hyades. This will be an exciting sight for stargazers, one that will look particularly magical through binoculars. So mark your calendar for Thursday April 7th and watch the show unfold all week long.

When the Moon emerges from the New phase and starts its 29 1/2 day journey around the Earth, the first few days are always a treat, because the waxing crescent offers so much to see through a telescope or binoculars, and even without optical aid, the sight of the thinly-lit Moon and the glow of Earthshine always catch your eye.

On Thursday, the Moon moves past the Pleiades star cluster, one of the best known clusters in the sky because the stars in it are fairly bright and concentrated into a small space, creating a kind of glow in the sky. Around the bright star Aldeberan in Taurus is the open cluster called the Hyades. These stars are also a close grouping in the sky, but not as tightly arranged, so you don't get the same kind of glow. However, through binoculars this cluster offers much to see.

Use the graphic (above) to help you orient yourself this week. You will want an observing location with a clear western horizon, away from streetlights or other distractions, and good weather. If you get all these conditions just right, you have no excuse for missing this gem of a celestial lineup. And if you live in San Francisco, come join me at the Cal Academy for a personal tour :-)

KFOG Podcast - April 4, 2011

2011-04-04T10:35:00.000-07:00

In today's podcast with Irish Greg of the KFOG Morning Show, we discuss the upcoming alignments of the Moon with star clusters in the evening sky, and I tell Greg about the upcoming festivities on Thursday in San Francisco at the Cal Academy's "NightLife" party celebrating Yuri's Night. It's quick and fun, so click here to listen.

Get Involved: Globe At Night, Lectures, California Academy of Sciences

2011-03-31T22:42:00.000-07:00

There is always something to do if you are interested in getting a bit more involved in astronomy. Right now, you can learn at a lecture, attend a star party, or take part in a global project to record light pollution while learning about new constellations. Read on for details.

Here in San Francisco, the California Academy of Sciences hosts a lecture series on astronomy topics. The Dean Lecture Series features talks on some of the most riveting subjects in astronomy, and Monday April 4th is the next talk, presented by Joel Primack and Nancy Ellen Abrams, focuses on the most modern research in cosmology, that of Dark Matter and Dark Energy.

The California Academy of Sciences also has a fun event every Thursday night with its "NightLife" series, transforming the museum into a fun party. Each week has a theme, and next Thursday April 7th is Yuri's Night, an annual celebration of the first man in space. If the skies are clear, you can find me on the Living Roof giving star tours alongside the docents of the museum showing off planets, nebulae and the Moon through telescopes.

If you don't live in San Francisco, visit the Night Sky Network website to find lectures and astronomy clubs in your area.

The Globe At Night project is now in the second phase, inviting Citizen Scientists around the world to support the effort to raise awareness of light pollution, learn about the night sky in your neighborhood, and pay attention to details of the constellation Leo the Lion. Take part - it only requires a few minutes and is an eye-opening experience.

Vernal Equinox, Super Full Moon, and other astronomical musings

2011-03-19T12:46:00.000-07:00

I enjoy sharing highlights of the sky with friends and have been blogging for several years now, pointing out events of astronomical interest here as The Urban Astronomer. I was surprised to see the excitement and questions about the Super Full Moon, the coincidence of nature that is leading to a full moon at perigee today. The fact that the general public is being scared into thinking something bad is about to happen is unfortunate, but the fact that people will be out tonight looking at the full moon is the good outcome that I wish for. Of course, there is absolutely nothing to be worried about. Every 29 days the Moon swings a bit closer to the Earth than other times of the month, and that pattern of perigee and apogee, full and new, repeats in a beautiful "super pattern" every 18 years, something now known (but likely not fully understood) by the many who are reading about the Super Full Moon being the biggest one in 18 years.

There are numerous patterns and cycles in the heavens. Tomorrow, March 20th, is the Vernal Equinox, the semi-annual moment when the length of the day is exactly 12 hours everyone on Earth. I like that dynamic, a twice-a-year event in which we are all given equal periods of sun above the horizon and below the horizon, regardless of your latitude, regardless of whether you are in the Northern or Southern Hemisphere. That is a moment of beauty in the grand annual rhythms of our home planet.

The pattern of lunar repetition that lasts for just longer than 18 years is also responsible for the cycle of lunar and solar eclipses that take place around the world. I witnessed a total solar eclipse in Europe in July 1999, and the celestial dynamics of that eclipse will exactly repeat in August 2017 when a wonderful total solar eclipse will sweep across the United States. For me, it will be a rare chance to be standing in the shadow of the Moon on the second passing of this particular alignment of Moon, Earth and Sun, one that will be far more dramatic and meaningful to me than any particular Super Full Moon you might encounter between now and then. But in the end, if you can find some meaning and solace looking up at the Moon tonight, savor the moment and mark your calendar for April 2029 when the conditions will align themselves and present you with a chance to relive this magic moment when you saw a particularly big and impressive full moon. That is something worth pondering, and the rest of the media hype you are hearing right now should be simply ignored.

Image courtesy NASA.

Jupiter and Mercury: Prograde and Retrograde Motion

2011-03-06T22:32:00.000-08:00

Elusive Mercury makes an appearance for the coming weeks in the evening sky, slowly progressing toward Jupiter as the two planets share the same space (from our point of view) just above the setting Sun. Although Jupiter is considerably farther away from Earth as Mercury, Jupiter's massive size more than makes up for that distance and makes it appear to us as a much brighter light on the horizon.

As Mercury rapidly arrives in the evening sky, it changes its location each evening quite a bit, and before long will be aligned with Jupiter, setting around the same time as Jupiter toward the end of March. As it reaches this point, it will then change its daily direction across the evening sky and move rapidly westward toward the Sun, something called "retrograde" motion. For a few weeks, people will say that "Mercury is in Retrograde" which is, from an astronomical point of view, very normal behavior for Mercury every few months. However, for many who follow astrology, this can be a very troubling time. Perhaps seeing Mercury with your own eyes changing location and moving gracefully across the sky, first in prograde motion (the basic motion of planets across the backdrop of stars, eastward), then in retrograde, will make its impact a little more friendly. Try it out for yourself and see.

KFOG Podcast - March 4, 2011

2011-03-04T11:51:00.000-08:00

As always, I had a good time at KFOG today talking with Morning Show co-host Irish Greg who has boundless enthusiasm for just about everything, including talking with me about all-things-astronomical. We even did some indoor stargazing (see photo) in the KFOG broadcast studio :-). Check out our podcast for the latest on what to see in the sky, and where to go to hear some excellent lectures and talks about astronomy.

Take part in "The Globe At Night" project - just look up at the sky tonight!

2011-02-27T14:40:00.000-08:00

For the next week everyone is invited to participate in a global effort to measure light pollution and to learn about stars and the sky in your neighborhood, especially for those in big cities like San Francisco. The "Globe At Night" project invites people from around the world to take a few minutes in the next 7 days and look at one of the most beautiful constellations in the sky, Orion, and simply report how much of it you can see. It's easier than you think. And it's a great family project to show kids what you can see in the night sky.

The Globe At Night website provides all of the details, but in summary you compare what you see in your sky (your backyard, rooftop or any other convenient observing location) to a series of images on the Globe At Night website. By finding the image that best matches your view and reporting this on the website, you are helping to gather data from cities around the world on the relative light pollution in the sky. The constellation Orion contains stars of varying brightness, and depending upon the darkness of your skies, you will see more or less of these stars. The charts on the Globe At Night website show you Orion with differing "magnitudes" of stars, so for very light polluted cities you might only see the 1st and 2nd magnitude stars, whereas in darker skies you will see 3rd, 4th, or even 5th and 6th magnitude stars (the higher the number, the fainter the star).

Join the worldwide "Citizen Scientists" supporting this effort to increase awareness of the night sky, and take part. And bring along a friend. It's fun!

Seeing Summer in Winter - Scorpius and Sagittarius

2011-02-22T08:42:00.001-08:00

The early morning sky this week holds some treasures for star gazers. As the view of the heavens changes from season to season, we have a chance to see the symmetry of our sky by looking south-east in the morning. In winter, we see the majestic winter sky in the evening, but by early morning we see the summer sky! How is this possible? Every 12 hours as the Earth rotates on its axis, we face the different constellations and in fact see the "opposite" season in the morning. This week, as the old Moon passes through the summer constellations of Scorpius and Sagittarius, it accentuates the rich beauty of these two constellations, both of which contain many treasures for the unaided eye as well as for those who wish to get out their binoculars for a closer look.

Sagittarius is located in same direction as the center of the Milky Way, and Scorpius is just next to this, so both contain a richness of nebulae and star clusters that are easy to find in binoculars. It's worth the extra 2 minutes in the morning to take a look if you can get outside before the first light of dawn, before 6:00 am in San Francisco.

The Winter Sky Beckons

2011-02-12T21:05:00.000-08:00

The Winter Sky beckons me to stop what I am doing and pay attention, for the view of the heavens in this magical season is unlike any other. Here in San Francisco, when it is not raining (as was the case for most of January through today), the air is dry and the atmosphere clear, giving the casual observer sparkling vistas into the heavens. And as this kind of weather happens with regularity in the winter, and the hours of darkness are at their maximum, it is all but impossible to miss the winter sky.

Evenings right now are dominated by the slowly fading planet Jupiter high in the west at sunset, and the colorful bright stars of Orion high in the southern sky, Canis Major and Sirius to the lower left of Orion, and Taurus and Aldeberan to the upper right of Orion. Facing north, the Big Dipper and Cassiopeia trade places every 24 hours, circling Polaris, the North Star. And later in the night to the east are a variety of treasures in Virgo with Saturn in the vicinity. Two weeks ago the morning sky featured the old Moon passing through Scorpios and Sagittarius, creating beautiful alignments that accented the eastern horizon at dawn.

The most important thing to do, if you want to see these amazing sky spectacles, is to keep your eyes open and look up - - nothing more than that is necessary to be captivated by the spell of the sky. No need for a telescope or binoculars. This time of year the stars dazzle in the night, and appear to be asking all of us to take a moment to contemplate their majesty and come to appreciate the universe, awaiting your view each night of the year.

Celestial Companions in the Cold Dark Morning

2011-01-27T22:54:00.000-08:00

January mornings are dark times, and when the sky is clear it is certain to be chilly outside. So I find the sight of the old Moon reassuring, a warm light that fades a bit each successive morning and guides the way through bright stars and planets along the ecliptic to the soon-to-be-rising-Sun. You can see this spectacle at its finest the next few mornings as the Moon moves a bit further eastward each day and passes near to some distinct celestial companions.

The Moon is passing now through Scorpius and the grey-white of the Moon stands in stark contrast to the red-orange of the star at the heart of the Scorpion, Antares. Moving close to Antares on Friday morning, the Moon continues toward the brilliant planet Venus on Saturday morning, and then slowly fades into the glare of sunrise on Sunday morning. My kitchen window faces south-east so I see this changing landscape each morning and I look forward to the coming days with clear skies in the forecast. If you rise before sunrise, take a moment to look out toward the south-east and enjoy the calm of this morning celestial grouping of close companions in the heavens.

KFOG Podcast - January 20, 2011

2011-01-20T15:53:00.000-08:00

My monthly conversation with KFOG Morning Show's Irish Greg moved from the new Zodiac signs (such as Ophiuchus) to the Aurora Borealis to the big bold winter constellations such as Orion and bright stars such as Sirius. Click here to listen and get inspired to look up at the sky tonight!

Northern Lights from 35,000 Feet – The Aurora Borealis

2011-01-09T10:35:00.000-08:00

I had the privilege of seeing the Aurora Borealis today while on a flight from San Francisco to Frankfurt, Germany. The Aurora, or Northern Lights, is a beautiful, eerie glow in the sky caused by the light pressure (Solar Wind) from the Sun hitting Earth’s upper atmosphere and causing molecules to glow where the Earth’s magnetic field is concentrated in a circle around the North Magentic Pole.

A bit of science: "Auroral Ovals" are regions on the Earth around the magnetic poles where Aurorae are most likely to occur, and because the Magnetic North Pole is in Northeastern Canada, the auroral oval extends to other reaches of Canada, Greenland, Scandinavia and the Arctic region. The website Spaceweather.com has a daily update on the size and location of the auroral ovals (scroll down and look on the left hand side of the homepage). Since I knew I was going to be on a flight to Europe that would take me far north and near to this region of the Earth, I made sure I had a seat on the left hand side of the plane and once on board, watched the flight map to follow our progress. Like most international flights that travel east, the flight moved quickly into darkness and at about the halfway point at which we were at the Arctic Circle, I started looking out my window. Not surprising at all, I began to see a faint glow on the distant northern horizon. Over the next 30 minutes, the glow became bigger and before long the plane was in the midst of what appeared to be clouds of light, glowing a faint green among the backdrop of circumpolar stars. Luckily there was no moonlight to distract from the view this night.

There is no way to easily describe the Northern Lights except as beautiful curtain-like clouds that glow of their own light, rather than being illuminated by sunlight. The shapes change continuously, and in the more dense regions the wing of the plane outside my window actually was illuminated by the glow. Moving along at high speed the view was always unfolding, always bringing new shapes into view. I watched for about two hours until the intensity began to wane.

If you are traveling a route that takes you far north (any West Coast to Europe flight will do) and it is in the late Fall and early Winter months, you should acquaint yourself with the auroral oval on Spaceweather.com and get a window that faces north (left hand side) when flying east. Be patient, darken your seating area, and look carefully, as you would for any item of astronomical interest. You’ll be rewarded with an unforgettable, magical show.

Quadrantids Meteor Shower - January 3-4, 2011

2010-12-30T20:53:00.000-08:00

2011 starts with an impressive meteor shower for those ready to brave a cold night. The Quadrantids take place the night of Monday January 3rd into the morning of Tuesday January 4th, and are made better by the fact that the Moon is new, meaning no interference from moonlight.

As always, the best viewing of any meteor shower is from a dark location, ideally away from city lights. But I have had some success right in my backyard in San Francisco by positioning myself away from direct lights such as streetlights and houselights, and allowing myself 5 to 10 minutes to adapt to the darkness. Once dark adapted, the winter sky shimmers and Quadrantids are readily visible. In dark skies outside of cities you can expect up to 2 meteors per minute, but in the City I am happy to see 1 meteor every few minutes. This year should be as good a show as any, and despite our rainy Northern California weather the outlook is good.

To see this shower, position yourself facing northeast but give yourself as much of a view of the sky as possible. A lawn chair is best (along with blankets and a hat), as the meteors appear to originate in the constellation Bootes in the northeast part of the sky, but the meteors radiate in every direction away from this point.

For some fun background and history of this meteor shower, check out Astronomy.com and NASA's "What's Up" blog series. Image is courtesy of NASA.

Stay warm, and here's to good skies!

Shimmering Early Morning Sky

2010-12-26T16:41:00.000-08:00

As we approach the latest sunrise of the year (January 4th at 7:25 am in San Francisco), the morning sky remains dark enough to see stars until well after 6:00 am. That means that the early riser is rewarded with some lovely sights to close out 2010 and welcome 2011. Brilliant Venus dominates the sky each morning, shining bright in the South-East well before dawn. This week the waning Moon presents a changing landscape as it moves past Saturn, the bright star Spica (see diagram on the right), and then later in the week Venus and Mercury. Following the Solstice-Total-Lunar-Eclipse, the Moon is tracking downward on the Ecliptic, meaning that each Morning it is following the planets from high in the sky on a steep angle toward the horizon.

If you are not an early riser, don't despair. I'll have a post about the Winter skies soon. All you have to do is look up (especially if you are up at midnight on New Year's Eve and have clear skies). The Winter is a fantastic time to enjoy the stars.

Image courtesy of Sky and Telescope Magazine.

Total Lunar Eclipse of December 20, 2010

2010-12-14T22:57:00.000-08:00

Monday night December 20th, we get to witness a very exciting astronomical spectacle, a Total Lunar Eclipse. This one promises to be a special one, capping the longest night of the year with the strange and beautiful view of the full Moon being blotted out by the shadow of the Earth. The geometry of an eclipse is fairly textbook, but the experience is quite dramatic.

This eclipse will be visible from the western hemisphere, meaning that anyone on the entire night side of Earth will have a view of the full Moon and will see the phases of the eclipse. In this particular eclipse, the Moon passes through the darkest part of the Earth's shadow (umbra) meaning that the entire surface of the Moon will no longer have direct sunlight shining on it, but because of the atmosphere of the Earth, refracted rays of sunlight will in fact bend around the Earth and illuminate the Moon, creating a trademark orange or reddish color on the Moon, an eerie effect indeed. The excellent NASA Eclipse Website has much more detailed information on the eclipse.

The event starts at 10:33 pm in San Francisco, as the partial phases of the eclipse take about an hour. The period of "totality" when the entire surface of the Moon is dark, lasts about an hour from 11:41 pm until 12:53 am, and then the Moon is slowly revealed again for another hour. Cross your fingers for good weather, dress warmly, and enjoy this fascinating spectacle of nature. And if you have binoculars or a telescope, use them - this is exactly the time to get a close-up look at one of the wonders of the sky.

Image courtesy of the Universe Today.

Geminid Meteor Shower 2010

2010-12-08T22:43:00.000-08:00

One of the best Meteor Showers of the year takes place in favorable conditions on Monday night December 13th into the morning hours of December 14th. The shower is called the Geminids, named after the constellation Gemini. The Geminids appear to originate from the constellation Gemini which rises shortly after sunset and is high in the sky around midnight. This point in the sky is called the radiant, and if you trace the paths of the meteors backwards, they will all converge in this point.

Meteor showers generally get better late into the night because the Earth is rotated in the direction of its orbit around the Sun and consequently we encounter a higher number of meteors, on average. This is certainly true for the Geminids, and in dark conditions after midnight you might see 1 or even 2 meteors a minute. Being winter, you have to really prepare for this by dressing extremely well for your local conditions. I plan to get up early and look for Geminids in the early morning hours of Tuesday 14th, since the Sun does not impact the viewing until after 6:00 am.

This year is particularly favorable for the Geminids because the Moon is at First Quarter and will not be a factor after midnight. Stay warm and enjoy the show!

Image courtesy of Earth Sky.

KFOG Podcast - December 3, 2010

2010-12-03T11:04:00.001-08:00

Today on the KFOG Morning Show Podcast with Irish Greg, we talked about the discovery of new stars in the galaxy, alien life forms right here on Earth, the upcoming Geminids Meteor Shower on December 13-14, the upcoming Total Lunar Eclipse on December 20-21, and Holiday Shopping including a special 10% discount on anything at Scope City in San Francisco (my favorite place to shop) if you mention KFOG or The Urban Astronomer. Click here to listen. And take advantage of the 10% offer while it lasts!

Brilliant Venus and Old Moon in the Dawn Sky

2010-11-28T21:30:00.000-08:00

With sunrise at 7:00 in the morning, I find this time of year to be one in which I can do some early morning stargazing without having to change my morning routine. This week the waning Moon provides a lovely scene against the backdrop of brilliant Venus, bright Saturn and the bright star Spica. The illustration demonstrates what to expect in the eastern skies as the Moon shrinks each day on its way to the New Moon on December 5^th. If you are a morning person with an interest in astronomy, this will be an excellent week for you. Get out your binoculars for an especially riveting view of these heavenly bodies, and take in a few minutes of beauty about an hour before the sunrise.

Review of iPhone Astronomy Apps: ISS Visibility and Iridium Flares

2010-11-22T21:06:00.000-08:00

Two of my favorite iPhone apps are ISS Visibility and Iridium Flares, apps that help you to locate satellites very precisely. I use these two apps extensively, anytime I have clear skies and want to enjoy the spectacle of dazzling satellites crossing the sky, even here in the bright city lights of San Francisco. Continuing from my previous post on iPhone apps, here are two more reviews.

ISS Visibility does exactly what it promises by telling you when and where to look to see the International Space Station. Transits of the ISS across the evening or morning sky are impressive, whether the viewing is of the space station crossing a broad arc across the sky, or a short appearance that ends in the impressive flickering and fade of the ISS as it crosses the Earth's shadowline from daylight to night. At a price of $1.99, ISS Visibility gives you simple-to-use charts based on your location, and shows you where to look along with a nice 2D map showing the location of the ISS over Earth as it passes your viewing site.

Iridium Flares are bright lights in the sky that shine when Iridium Satellites in orbit around Earth reflect sunlight back toward the planet and produce a particularly bright glint of light in the sky for a few seconds. I find iridium flares wonderful to watch because at their best they flare up to -7 or -8 magnitude, many times brighter than Venus or Jupiter at their brightest. Also, being able to predict these special events is quite a lot of fun. I love to show off iridium flares to friends when the conditions permit. The Iridium Flares iPhone App costs a mere $0.99 but will pay back many times over.

Enjoy these two apps to see things in the sky that will certainly impress you.

Leonid Meteor Shower 2010

2010-11-15T21:23:00.000-08:00

A very fine meteor shower arrives this week. The Leonids peak on the night of November 17 and morning of November 18th, bringing a fairly reliable collection of meteors to the eastern skies. Best viewing is well after midnight into the early morning hours (around 4:00 AM until sunrise), when the Moon will have set and the Earth is better positioned to intersect more meteors.

Star Date Online has a nice article and image about the Leonids, so named because they appear to originate in the zodiac constellation of Leo. The constellation rises in the early morning sky and dominates the eastern sky. As the Sun does not break the darkness of the morning sky until 5:30 AM, the best darkness will be from 4:00 until 5:30 at which an observer in dark skies can see dozens of meteors per hour. Another good online resources is Astronomy.com with a good article on the Leonid shower.

Image from Astronomy.com.

KFOG Podcast - October 26, 2010

2010-10-26T17:04:00.000-07:00

Today's Urban Astronomer talk with Irish Greg of the KFOG Morning Show features the North Star, Meteor Showers in November and December, some early shopping tips for the holidays, cool iPhone Apps, Jupiter and more. It's always a treat to talk with KFOG and share some astronomy tips with the listeners. Click here to listen.

Waning Moon, Morning Darkness

2010-10-24T22:38:00.000-07:00

Each month the Moon makes a 29 1/2 day journey around the Earth, bringing different faces of the Moon to light, making beautiful patterns with the surrounding stars and planets, and shining light into the evening, midnight or morning skies. Right now, the Moon is waning, getting smaller each night as it passes through gibbous phases while moving from Full Moon to Last Quarter, lining up with bright celestial objects such as the Pleiades and Taurus. During the gibbous phases, the orientation of the Moon is quite different from what we normally expect in the evening skies.

The illustration shows the changing orientation of the Moon just after sunset in the waxing phases, as the Moon grows from New to Full. This view is for Northern Hemisphere viewers. But after the Full Moon, the orientation reverses and is best measured in the sunrise sky. So the view you can see right now is of a Moon curved not toward the east as normally seen in the evening sky, but rather curved toward the west in the morning sky. It's refreshing to see this time of year while it is so dark in the morning, and it provides a chance to see things in a different light. Eye-opening.

Image courtesy of University of Virginia.

An Elusive Comet in Urban Skies: Hunting for Hartley 2

2010-10-12T01:40:00.000-07:00

Comets can be bold and brash, streaking across the sky like Hale-Bopp in 1997 (see image on right), a comet that was visible even in light-polluted urban areas. Comets can be more humble but then unexpectedly brighten, as did Comet Holmes in 2007. This year marks the return of periodic Comet Hartley 2, a small but frequent visitor to the inner Solar System that is making a fairly close pass to the Earth (11 million miles) on October 20th. Because of the bright Moon on October 20th, this and last week mark the best chances to see the comet because the Moon is young and not brightening the sky. So I took a look last week and again this week to see if I could spot this elusive comet from a city location (last week in a suburb of Frankfurt, Germany and this week from my home in San Francisco).

I hunted quite a while on both occasions, using this very helpful map from Sky and Telescope Magazine. In fact, S&T has been running updates as viewers report seeing Comet Hartley 2 with binoculars. However, it seems that to see Comet Hartley 2 you need a location with very dark skies. I can attest to this, having twice tried and failed to discern the comet from the surrounding stars.

However, all is not lost. Searching for Hartley 2 requires you to find Cassiopeia, Perseus and Auriga, three very nice constellations that grace the Fall and Winter skies. While searching the path of the comet, you encounter a range of deep space objects near and between Cassiopeia and Perseus, and tonight the view was quite good. So even though city lights may have drowned out the faint comet, I enjoyed my first good look at the Double Cluster in Perseus and other celestial gems in the spiral arm of the Milky Way that is beyond Cassiopeia.

I recommend a good jacket, a comfortable chair or blanket, a few minutes patience, the S&T sky map, and binoculars. No matter whether your hunt for Comet Hartley 2 is a success or not, you will be glad you made the effort.

Autumnal Equinox and the rate of change of the length of the day

2010-09-22T22:06:00.000-07:00

Today is the Autumnal Equinox, one of two Equinoxes of the year. These are days that mark the transition from one season to the next, but also are days that have very special significance as the Earth orbits the Sun. Because of the tilt of the Earth's rotational axis, the Northern and Southern Hemispheres receive radically different amounts of sunlight from June through December, as the seasons progress from Summer to Fall to Winter (northern hemisphere). This is well understood and we learn from basic science courses that the in-between points while transitioning from Summer to Winter, for example, are the days that have equal periods of the Sun above the horizon and below the horizon -- equal duration of night and day -- hence Equinox. Today, everywhere on the planet, the Sun spent exactly 12 hours above the horizon and 12 below, and the Sun rose due East and set due West. From now through March, the Sun will be above the horizon more than 12 hours a day in the Southern Hemisphere, and less than 12 hours a day in the Northern Hemisphere.

I love the symmetry and simplicity of the Sun's motion on this day. It marks a transition as the days are getting shorter in the Northern Hemisphere. Everyone can feel the shortening of the days and sense, innately, that the changes in daylight and darkness are sudden and surprising. This is another fascinating change happening at the Equinox, more subtle but no less fascinating to me. When people sense the changes to the onset of darkness in the evening or the late sunrise in the morning, they are noticing that the length of the day is changing quite quickly and they feel that the times of day that might have been bright and sunny only a few weeks ago are now getting dark. At the time of the Equinox, the length of the day is changing most rapidly. For example, here in the San Francisco Bay Area, the longest day in summer is nearly 15 hours long and in winter the shortest day is approximately 9 1/2 hours. As the seasons change, the time of sunset and sunrise changes slowly, starting at the solstice in June - maybe only 1/2 to 1 minute per day. But then the changing becomes more rapid approaching the Equinox. At the time of the Equinox this week, the length of a day is changing 3 minutes per day -- that is, about 20 minutes in one week! So if you feel like the length of the days is changing very fast, you are absolutely correct.

The change is even more dramatic the farther north or south you are. For example, in Alaska, the length of the day is changing right now about 5-6 minutes per day, or about 40 minutes in one week! Imagine how that would feel, and it is a natural thing that happens every Spring and Fall. I think it is amazing how much the seasons impact the different geographies of the world, and a little understanding of the natural foundation for these effects is a nice thing to have.

Jupiter's closest approach to Earth

2010-09-20T09:25:00.000-07:00

Today Jupiter is at its closest point to Earth for 2010, a mere 368 million miles. Although not a particularly astonishing event, it is nonetheless a prime time to get out your binoculars or telescope to view the giant planet as it dominates the night sky. Jupiter is a fun target to view up close because it offers so much to see: Four bright Moons, colors and textures from its cloud belts, and for a brief time right now it guides you to find the distant planet Uranus.

Every year as the Earth moves around the Sun, at some point in time it is at its closest approach to Jupiter. This moment is called "opposition" and is when the Earth, Sun and Jupiter are all in a perfect line. Each year the distance between the Earth and Jupiter might be a bit more or less depending upon the circumstances of each planet's orbit. This year, the distance is smaller than usual (closest since 1963 and until 2022), but that difference is relatively small from year to year. More important is that the planet is at its brightest for the year, and remains high in the sky for optimum viewing for the entire night.

Sky and Telescope Magazine has an excellent article about this close encounter if you want more details.

Blue Star, Red Star, Yellow Star

2010-09-14T23:08:00.001-07:00

When conducting a star party, I always point out star colors. Most of the time, people see the stars as uniformly white, but in fact upon closer inspection it's easy to see that stars have color, sometimes very dramatic color. This time of year there are several colorful bright stars that illustrate nicely the range of what you can see in the sky.

The southern sky is dominated by the distinctive shape of Scorpius, the Scorpion of the Zodiac constellations. The "heart" of this constellation is the bright red supergiant star Antares. It is in the middle of the body of the scorpion and it is one of the biggest stars we can see, so big that if places in the Solar System it would enclose Mercury, Venus, Earth and Mars. To the observer, it looks a reddish-orange color.

High above this time of year is the Summer Triangle, featuring three of the brightest stars in the sky. One of these three is Deneb in the constellation Cygnus, the "Northern Cross." Deneb appears blue to the observer and in fact is indeed a blue-white supergiant star, similar to Antares in terms of massive size, brightness and distance from the Sun.

These two beautiful stars should be enough to whet your appetite for detail when you look at the night sky. They are bright enough and easy to spot and display color quite nicely. But don't stop there. A simple pair of binoculars gets you enough resolution to see an amazing array of color in so many of the stars in the sky.

The colors of the stars is an indication of their temperature. Like the different levels of heat in flame, the colors of stars follows a similar pattern with red being cooler and blue being hotter. There are yellow stars, hotter than the red giants, and next in line are white stars, cooler than the blue stars. Details of Stellar Classification and Color Index are documented on very fine websites for those who want to learn more about star colors.

KFOG Podcast - September 10, 2010

2010-09-10T16:21:00.001-07:00

Another fun visit with Irish Greg of the KFOG Morning Show, today featuring a discussion of constellations to see this time of year (Sagittarius, Scorpius, The Summer Triangle) and the difference between an asterism and a constellation, plus deep-space objects you can see in the Milky Way with an ordinary pair of binoculars. And the latest happenings with the Moon and Venus, and an update on a great star party and lecture this weekend. All in 7 short minutes! Click here to listen.

Get Involved: Astronomy Lectures, Star Parties and more

2010-09-08T22:58:00.000-07:00

The Bay Area has many great astronomy resources and if you want to expand your knowledge of the universe and have a good time, check out one of these upcoming astronomy-oriented events.

Star Party and Lecture on Mount Tamalpais: The San Francisco Amateur Astronomers (SFAA) hosts monthly lectures and star parties at the Mountain Theater on Mount Tam in Marin County from April through October. Ken Frank is giving a talk this weekend (Saturday 11th September at 8:30 pm) on the Globe At Night project, highlighting the effects of light pollution

worldwide. Details on the Mount Tam website. Following the lecture, the SFAA has telescopes set up for public viewing.

Benjamin Dean Lecture Series at Cal Academy: The California Academy of Sciences in Golden Gate Park in San Francisco hosts excellent programs on many areas of science. The Dean Lectures focus on astronomy and this month (Monday 13th September at 7:30 pm) the talk is on the Search for Extraterrestrial Intelligence (SETI) with Jon Jenkins of the SETI Institute. Tickets and information at the Cal Academy website.

The San Francisco Amateur Astronomers monthly meeting is always open to the public. This month's meeting features NASA Ames astronomer Chris McKay speaking about extreme environments on heavenly bodies in the Solar System. The meeting is on Wednesday 15th September at 7:30 pm at the Randall Museum in San Francisco. More details on the SFAA Website.

I hope to see you at one of these excellent events.

Perspective of the Solar System

2010-08-23T18:19:00.001-07:00

After weeks of foggy skies in San Francisco, the sky has started clearing, yielding spectacular sunsets and sky shows at Ocean Beach. I have been writing about (but not seeing much of) the amazing sight of the planets dancing across the evening sky. With the clear skies, the view was great, showcasing Venus and Mars very close together, with Saturn just to the lower right and the bright Zodiac start Spica (in Virgo) just to the upper left.

This configuration traces a curve in the sky and if you have a clear southern horizon you can "connect the dots" from this cluster of stars and planets to the south where bright Jupiter dominates the sky. Beyond that, the Moon is slicing across the lower southern sky, providing the observer with a nice visual of the Ecliptic, the line of the planets, Moon and Sun. This is a great way to visualize the path of the planets in the Solar System when you look out from our Earth-bound perspective.

Over the coming months, Mars and Saturn and eventually Venus fade, but the giant planet Jupiter will be dominating the Fall skies.

Perseid Meteor Shower 2010

2010-08-11T09:15:00.001-07:00

The Perseid Meteor Shower reaches its peak this week and the timing is very good for a fine display of meteors. Every year when the Perseids come around, the biggest concern is the Moon. Its beautiful light is a welcome sight to many, but for amateur astronomers and anyone wishing to see more than a few meteors, moonlight can ruin an otherwise-perfect evening of viewing. This year the Moon is very young during the Perseids and sets not long after sunset, leaving a dark sky for the shower.

The Perseids peak on the nights of Thursday 12th and Friday 13th, with best viewing on Thursday night / Friday morning. You can get detailed information on the Sky and Telescope website or on numerous other web resources.

The best way to see the meteor shower is to find a dark location, give your eyes plenty of time to adapt to the darkness, and be prepared to stay up late (or get up early). Meteor showers are almost always best viewed after midnight when the Earth is powering directly into the meteor stream and the rate increases substantially. The Perseids appear to originate in the constellation Perseus which is in the east after midnight, but that does not mean you have to specifically look east to see the meteors. Lying on a blanket facing directly overhead gives you the most expansive view and you can see meteors coming from the east or passing overhead toward the west. Meteors are wonderful, fast, elusive wonders and you simply need to be warmly dressed, in a place where you can see as much of the sky as possible without light distractions, and patience. I wish you clear skies and a great night or two observing.

Trio of Planets

2010-08-02T22:43:00.000-07:00

The evening sky brings us a trio of planets in a close grouping this week. The bright beacon of light, Venus, shines brightly and moves quickly from night to night, especially by comparison to the slower-moving Mars and Saturn. The image shows the view on Sunday August 8th, so looking at this earlier in the week you will find Venus lower and to the right of the other two planets, and after the 8th you will see Venus glide to the upper left of the two planets. We are witnessing the motion of Venus along its orbit around the Sun, moving much more quickly from our vantage point on Earth than Mars and Saturn. Venus will continue to dominate the evening sky for many weeks to come.

KFOG Podcast - July 16, 2010

2010-07-16T18:13:00.000-07:00

I was in San Francisco this morning recording another podcast for the KFOG Morning Show Podcast Series. Morning Show Producer Irish Greg and I had a very spirited and lively conversation about planets, the Solar System, Star Parties, Iridium Flares, Dark Energy and Dark Matter. In a fast-paced 9-minute conversation we discuss everything from the phase of the Moon to the origin of the Universe. Get inspired to see the sky tonight: Click here to listen.

A Must See: Four Planets and the Moon

2010-07-11T21:07:00.001-07:00

This week the sky features four of the brightest planets in a beautiful lineup in the sunset sky. The illustration on the left, borrowed from Sky & Telescope Magazine, demonstrates how the planets all align themselves in a path across the sky known as the Ecliptic. This line in the sky, actually a gentle curve from west to east across the south part of the sky, is the plane of the Solar System as viewed from our observing platform on Earth. We see fast-moving Mercury close to the Sun, then Venus, Mars and Saturn, a most impressive line-up.

To set this into perspective, the young Moon emerges from the glare of the Sun on Tuesday 13th, moving somewhat parallel to the Ecliptic but each day a bit farther south of the Ecliptic. This is because the orbit of the Moon around the Earth is slightly inclined to the rest of the bodies in the Solar System. And as we just had a Total Solar Eclipse on Sunday, the Moon is following a path away from the Ecliptic into what is called the "descending node" south of the Ecliptic.

I will be talking about this at the California Academy of Sciences at their Nightlife event this Thursday in Golden Gate Park. If you are in or near San Francisco, please join me on the roof for Star Tours!

Total Solar Eclipse 2010

2010-07-09T19:14:00.000-07:00

One of the most dramatic spectacles of nature takes place Sunday July 11th, as the New Moon passes in front of the Sun and creates a Total Solar Eclipse over the South Pacific Ocean. This eclipse will be especially unique for those who travel to Easter Island to see it. As the shadow of the Moon sweeps across the ocean at speeds of up to 1000 miles per hour, the darkness will pass directly across Easter Island and the famous Moai, the large stone statues that are nearly 1000 years old.

I have experienced Total Solar Eclipses in the past and they are remarkable, not only for the brilliant image you see in the sky, but also for the dramatic changes in the environment you experience as the sky slowly darkens, the horizon changes color, the animals begin to react strangely, and the fellow eclipse-chasers react with great anticipation. Although I will not travel to this one, I plan to travel to one of the upcoming eclipses in the next few years.

For those in the US who don't want to travel far, your next chance to experience at Total Solar Eclipse will be 2017.

Star-and-Planet Drama

2010-07-05T22:31:00.001-07:00

The evening sky over the next few weeks offers a study in the changes that take place in the sky along the path of the Moon and the path of the planets. This is exciting to watch and helps to unveil some of the intricacies of the Solar System, something you can see right from your own backyard. For quite a while now I have been particularly fond of sharing the path of the planets across the sky (the "Ecliptic") while conducting star parties and giving astronomy talks. I find that the ability to visualize this band across the sky is an important one for those who wish to have a basic understanding of the motion of the planets across the sky. And for several months the bright planets, a collection of bright stars, and the monthly sweep of the Moon across the sky have provided a perfect laboratory for learning. This month is no exception.

Shortly after sunset there is an excellent parade of planets and stars easily visible as the glare of dusk fades, starting with brilliant Venus in the west, and then in succession from west to south are Regulus, Mars, Saturn and Spica. These bright objects show the line of the Ecliptic.

At the end of this week there is a total solar eclipse (unfortunately not visible

from the San Francisco Bay Area). The eclipse comes at the middle of an Eclipse Season and as such, the Moon follows a descending path below the Ecliptic in the days that follow the eclipse, in particular from the 12th to the 17th of July. As it moves from day to day, it swoops just below the Ecliptic and makes a pleasant arc across the southern sky below Venus and Regulus, then Mars, then Saturn and then Spica.

And in addition, we are just coming into a period of time when fast-moving Venus has close encounters with the other planets and stars along the Ecliptic, starting with a close encounter of Regulus on the 9th of July. More drama to come in the next few weeks -- stay tuned!

The Path That Leads to the Earth's Shadow

2010-06-19T08:11:00.000-07:00

We are in an "Eclipse Season," a five week period of time when the Moon's orbit around the Earth is aligned in a way that the Full or New Moon crosses the path of the Earth around the Sun. When that happens, we experience a Lunar or Solar Eclipse and right now we have one of each coming up: a partial Lunar Eclipse on Saturday 26th, and a total Solar Eclipse on July 11th. The Solar Eclipse will not be visible from North America so we don't get a chance to experience that, but the Lunar Eclipse will be. More on that next week.
During an Eclipse Season, the Moon's position in the sky is special, as it is moving just above or just below the plane of the planets (the "Ecliptic") in the interval from New Moon to Full Moon. A few days ago as the Moon emerged from the evening glare waxing each evening, you could see it move just below Venus, then below Regulus and Mars, and now it is below Saturn and Spica, all objects on or near the Ecliptic. As it nears Full Moon and the Lunar Eclipse on the 26th, it is moving closer and closer to the Ecliptic and will intersect the Earth's shadow on the 26th.
I like to imagine that there is a dark spot in the sky where the Earth's shadow projects out into space. Every month as the Moon nears Full, it sweeps close to that spot. But only during an Eclipse Season -- every six or twelve months -- does it slip into the shadow of the Earth and display to all of us the curved shadow of the Earth. That is something to look forward to next weekend.

Heavenly Line-Up

2010-06-11T04:29:00.000-07:00

Over the past months the evening sky has been graced by a number of bright stars and planetary configurations. As summer approaches and these stars and planets move westward toward the sunset day after day, heavenly line-ups are emerging that are beautiful to see and are dynamic in nature, changing dramatically from one day to the next.

This evening the planet Venus moves into a very impressive alignment with the two “twin” stars of Gemini, Castor and Pollux. Although Venus is considerably brighter than the two stars, the pattern of the three celestial objects will be distinct, emerging from the sunset glow with Venus as the guide star and Castor and Pollux shining a short while later.

On the 13^th and 14^th, the trio is joined by the young crescent Moon. The combination of these heavenly bodies in the twilight should be an impressive sight indeed.

KFOG Podcast - June 4, 2010

2010-06-04T22:58:00.000-07:00

Today I spent a few minutes talking with Irish Greg of the KFOG Morning Show for their podcast series. Greg is one of those people with boundless enthusiasm and an insatiable appetite for discussion about any topic, so when we talk astronomy it's always a good time. Today's conversation ranged from the Summer Solstice to the upcoming lineup of Mars and Venus and some bright stars, to the June 26th Lunar Eclipse and the Search for Extraterrestrial Intelligence (SETI). Click here to listen.

High in the sky: The Big Dipper

2010-05-29T12:15:00.001-07:00

The Big Dipper is one of the easiest groupings of stars in the sky to identify, and it serves as a guide to some of the more interesting stars in other parts of the sky. Late Spring evenings it is nearly overhead as seen from San Francisco, and its distinctive pattern provides an interesting exercise for understanding the motions of objects in the heavens.

The Big Dipper is not a constellation, by strict definition, because it is only the brightest 7 stars of the larger constellation Ursa Major. A named combination of stars within a constellation such as the Big Dipper is known as an "asterism." Because of its distinctive shape, the Big Dipper is a very well known asterism, one of several celestial groupings that lives up to its name (I put Leo, Scorpius, Cygnus and a few other constellations in this special class).

The Big Dipper points to the North Star (Polaris) if you follow the two stars at the side of the bowl of the dipper. This Wikipedia article illustrates this nicely. The line along the pointers from the Big Dipper to Polaris is helpful because this line is similar to an hour hand on a 24-hour clock. Every 24 hours the Big Dipper makes one counter-clockwise rotation around Polaris. From latitude 38 degrees north (approximately the latitude here in San Francisco) the Big Dipper is high in the sky when it is above Polaris (as it is now at sunset) and low in the sky when it is rotated half way around Polaris just above the horizon (as it will be in late Fall evenings).

The three stars in the handle of the Big Dipper form a curve, and if you think of this curve as an arc, you can follow it to a very bright star called Arcturus (in the constellation Bootes), and by continuing along this arc you end up at another bright star called Spica (in the constellation Virgo).

One more fun thing to find in the Big Dipper is the middle star of the handle, known as Mizar (see image above). This star has a very close companion, Alcor, next to it and if you want to test your eyesight, see if you can split the two without using binoculars or a telescope.

Enjoy learning about the Big Dipper in the pleasant weather of May and June. It's full of surprises and one of my favorite stops when sharing the sky with friends and guests at star parties.

Planets and Bright Stars along the Ecliptic

2010-05-08T17:13:00.000-07:00

This is a great time of year to enjoy the view of bright stars and planets demarcating the ecliptic. I am hosting a lot of star parties these days (last week in Tomales, this week in Fremont, next week in Healdsburg and the week after in San Mateo) and I always love to point out the ecliptic, the band across the sky where the planets and Moon are found in their wanderings across the heavens.

The ecliptic is the plane of the Solar System, the imaginary line across the sky that marks the orbits of the planets and the Moon. In a planetarium this can easily be shown, but under the heavens it is daunting to visualize this. I use a laser pointer to show the path across the sky, and that helps to visualize this, but right now the skies are cooperating to make this a bit easier for those of you without an amateur astronomer and a laser pointer :-)

Face South about 30-45 minutes after sunset and you will be looking toward the ecliptic. It stretches from the point of sunset to your right (West) where bright Venus gives you one reference point, then stretches up and toward the south to Castor and Pollux, the two twin stars of the zodiac constellation Gemini. Just to the upper left of the pair is bright orange Mars, and continuing left you encounter blue-white Regulus, the brightest star in the zodiac constellation Leo. Now the line of the ecliptic moves down toward the East, that is, down and to the left as you face South. Lower left of Leo is the planet Saturn, a bright, milky-white dot of light. And continuing to the lower left of Saturn is the bright star Spica, in the zodiac constellation Virgo.

Enjoy the tour, and if you have a star chart, put it to work so you can use these bright points of light to help you learn a few constellations. Even in the big city, all of these are visible.

The image on this page was copied from Nick Strobel's Astronomy Notes. Go to his site at www.astronomynotes.com for the updated and corrected version.

A Beacon in the Twilight

2010-04-25T14:49:00.000-07:00

As the days grow longer and the last vestiges of twilight linger later in the evening, look to the West this week for some very beautiful planetary/celestial lineups. The week features fast-moving Venus passing very near to some of the most spectacular star clusters in the night sky, the Pleiades and the Hyades.

When you look into the twilight sky, the brightest objects shine majestically against the bright blue background. That is the case for Venus this week, as it is for the young crescent Moon each month when it shines low in the West in the first few days after new Moon. However, in order to see the star clusters near Venus, you will need to use binoculars. The stars are there to see, but the bright twilight makes them all but invisible to the naked eye. It's worth the time to get out and see this spectacle. Sunset in San Francisco is just before 8:00 pm, and the sky will be dark enough about 45 minutes to an hour after that.

KFOG Podcast - April 14, 2010

2010-04-14T20:49:00.001-07:00

Mars and the Beehive

2010-04-09T22:11:00.000-07:00

Over the past few weeks I have been watching the gradual change in position of Mars as it moves from retrograde to prograde motion across the sky, now moving steadily eastward across the constellation Cancer and next to a beautiful cluster of stars knows as the Beehive Cluster, or M44.

Mars, like all other planets, moves eastward from our point of view most of the time but when Earth have just the right alignment (as we did with Mars over the last few months) a planet may appear to travel westward, and we call this motion "retrograde." Click on the image to see how Mars was in retrograde from December through March.

Now that Mars is moving eastward again, it is traversing a part of the constellation Cancer where you can find the Beehive Cluster, an open cluster of stars (like the nearby Hyades cluster in Taurus). It is relatively close to the Solar System compared to most clusters, and it is a gem in binoculars. With Mars as your guide "star" you can easily navigate to the Beehive Cluster high overhead this time of year. It's worth a few minutes to see if you can spot it.

Seeing Mercury in the evening sky

2010-03-28T09:20:00.001-07:00

Mercury makes its way into the evening sky, visible shortly after sunset for the next few weeks. The fleet-footed planet never strays far from the Sun from our point of view, so we get glimpses of Mercury in the evening, then the morning before sunrise, and again in the evening several times a year. Right now Mercury is going to be easy to find because it will move near Venus this week. Venus is the bright evening "star" in the west, shining through the glow of dusk, and Mercury, although dimmer, will be fairly easy to spot now that you know where to look.

Full Moon Fever

2010-03-27T08:59:00.000-07:00

It's time for the first full moon of Spring, rising up to dominate the sky Monday evening. The first full moon following the Vernal Equinox (the moment when Spring arrived on March 20th) marks the arrival of Passover and Easter week, holidays that are based on lunar calendars. The Moon passes near Saturn on its trek across the eastern sky in the early evening on the 28th and 29th, and then onward toward the bright star Spica on the 30th. The Moon is full at exactly 7:25 pm pacific time on Monday 29th.

Winter Triangle

2010-03-16T15:00:00.000-07:00

One of the highlights of the winter sky is the Winter Triangle. This shape is a nearly perfect equilateral triangle that shines in the southern sky over the next few months. It includes three of the most brilliant stars in the sky, and it is called an "asterism" because it is not a single constellation, but a combination of stars from three different constellations.

The first and brightest star is Sirius, the brightest star in the night sky. Sirius is close to the Solar Systems (8 light years) and has a slight blue coloration. Sirius is in the constellation Canis Major, the big dog that accompanies Orion. To the upper right is Betelgeuse, a red supergiant star in Orion that is a distinctive orange color. Betelgeuse is so big that if it was our Sun, it would envelop Mercury, Venus, Earth and Mars! And the third star of the triangle is Procyon, in the constellation Canis Minor, the small dog that accompanies Orion. Procyon is actually a double-star system with a faint partner star.

Inside the Winter Triangle you can find numerous clusters of stars. I spent some time looking here a few nights ago and was able to see quite a few of these clusters, even in San Francisco. My backyard has a dark western horizon so by looking through binoculars later in the evening I was able to see quite a bit in and around the asterism. Try this for yourself sometime soon.

KFOG Podcast - Mar 16, 2010

2010-03-16T13:07:00.000-07:00

Get Involved: Chart the Skies, Hear a Lecture, Attend a Star Party

2010-03-12T10:02:00.000-08:00

There are many ways to take your interest in astronomy up a notch. Here are a few things that are sure to enhance your interest and knowledge of the skies.

Globe at Night: I am a big fan of this annual project, one that combines astronomy with awareness of light pollution and is also a global participation project. Go outside tonight and look up at Orion, then report what you see at the Globe at Night website. It only will take a few minutes but it will change how you see the sky at night. I am certain about this one.

Lecture: Each month the San Francisco Amateur Astronomers hold their meeting at the Randall Museum in San Francisco. The meetings are open to the public and feature a speaker on a topic of interest in astronomy. This month the meeting takes place on March 17th and features Andrew Pohorille from NASA Ames Research Center for a presentation on "The Origins of Life in the Universe."

California Academy of Sciences Nightlife: Every Thursday the Cal Academy stays open late for a fun, festive evening with music, drinks and science. When the skies are clear you can stargaze and look up close at the universe through telescopes on the Living Roof. And this week, on Thursday March 18, I'll again be a guest at NightLife giving a talk about the Night Sky and laser-guided star tours on the roof. I hope to see you there. (note: must be at least 21 years of age)

Star Parties: The San Francisco Amateur Astronomers host monthly star parties at Lands End in San Francisco, weather permitting. The next on is on Sunday March 21st. And on April 17th the Mount Tamalpais lecture series and star parties return. These are an excellent combination with lectures at the Mountain Theater and star gazing in a dark setting atop Mt. Tam. You won't be disappointed -- even when it is foggy in San Francisco it is generally clear and dark on Mt. Tam.

The Moon and the Ecliptic

2010-03-07T22:10:00.000-08:00

Continuing from the last post, here's a snapshot of the Moon continuing on its journey across the morning sky, a series of guideposts to the Ecliptic. The view is what you would see around 5:30 am each morning here in San Francisco.

Moon Traveling Along the Ecliptic

2010-02-27T18:56:00.000-08:00

The Moon, like the planets and the Sun, travels along a special path in the sky called the ecliptic. Observationally, the path arcs generally across the southern half the sky from west to east, but it is not a simple arc that is in the exact same part of the sky year round. Rather, it curves higher in the sky and lower in the sky as the seasons change.

Right now, in late winter, the Sun remains low in the sky but is gradually climbing the ecliptic, getting slightly higher each day. The Moon this week is just past full, and therefore is traveling along the opposite side of the ecliptic in a part of the sky where the ecliptic follows a low arc in the sky from west to east. And because the Moon takes 29 days to circle the Earth once, and the Sun appears to take 365 days to "circle" the Earth once, we can observe the Moon's motion along the ecliptic much more readily than the Sun's. The image helps to visualize this over the course of four days in which the position of the Moon at the same time in the dawn (an hour before sunrise, about 5:30 to 5:45 am this week in San Francisco) traces out the low, sloping arc of the ecliptic -- and slices close to Saturn as well.

The Urban Astronomer speaks!

2010-02-26T15:25:00.001-08:00

I want to let Bay Area readers know about a very exciting event coming up on Tuesday March 2nd in San Francisco. The event, Ignite Bay Area, is one of a collection of global "Ignite" events happening next week. If you have never experienced an Ignite presentation, they are very fast and focused 5-minute talks about everything from geek technology to social trends to .... astronomy! I'll be presenting a talk on amateur astronomy that I trust will inspire and motivate many to look up in the night sky and make a cosmic connection. Hope to see you there!

Winter Sky Show: Gemini, Mars and the Moon

2010-02-23T23:38:00.000-08:00

Gemini is one of the finest constellations you can see during the winter months, easy to spot because it traverses the highest spot in the sky (the zenith) and features two bright stars, the twins Castor and Pollux. These two stars are well known because they symbolize the heads of the mythical twins. The stars that make up the rest of the bodies of the twins are less bright and require slightly darker conditions than we will have this week, but I provide an image nonetheless so you can see the rest of the stars when conditions permit.

Mars is the bright orange beacon of light that is gracing the night sky, the brightest object high in the sky for the next many weeks. As Mars orbits the Sun, we observe it moving against the backdrop of the Zodiac constellations, changing its position gradually from month to month as it travels eastward from our Earthbound perspective (this is called prograde motion, in contract to retrograde motion – more on that in a future post). It is about to start moving away from the twins of Gemini through Cancer toward Leo the Lion where it will arrive in May.

The Moon sweeps through this busy part of the sky, passing slightly south of Gemini, Mars and later this week the bright star Regulus in the constellation Leo. The bright Moon will drown out the background stars of these otherwise bright constellations, but the prominent stars Castor, Pollux and Regulus, along with Mars, will shine beside the waxing gibbous Moon. Binoculars or a telescope are a good idea if you want to see this close up!

KFOG Podcast - Feb 12, 2010

2010-02-12T20:56:00.000-08:00

I've been a frequent guest on KFOG 104.5-FM in San Francisco for the last two years. I am going to start a new series of programs with KFOG's Irish Greg that they will include in their Morning Show "Web Show" page. I am looking forward to regular recordings with KFOG, keeping the Fogheads up to date with the goings-on in the sky. Here's the first of our recordings with conversation about what to see in the Winter sky, a few words about the San Francisco Sidewalk Astronomers, and some tips for telescope shopping.

Old Moon, Young Moon

2010-02-09T22:59:00.000-08:00

Every 29 1/2 days the Moon completes one cycle in its orbit around the Earth. For the last few days of the cycle we have an "old moon" and then just after New Moon we have the opportunity to see a very "young moon." I love the challenge of locating the very thin crescent Moon on the horizon, but when found, the reward is worth it, because the Moon always looks a jewel in the sky.

This week we've had a few opportunities to see the very old moon passing by Mercury in the dawn glare. After the New Moon on Saturday, find a good western horizon and try to locate the very young Moon in the glow of dusk. On Sunday 14th it will pass just next to Jupiter and Venus, extremely low on the horizon. You will want to have binoculars nearby to enhance the view. On Monday the Moon is higher in the west, and by Tuesday it is an easy target in the sunset sky. Well below the Moon on Tuesday, however, Jupiter and Venus have their closest approach for quite a while, being about 1/ 2 degree apart (a moon width). For this, you will want binoculars because the two planets will be just on the horizon after sunset.

Get Involved: Cal Academy, Star Parties, meet John Dobson

2010-02-08T23:18:00.000-08:00

February is a busy month here in San Francisco for those who are ready to take a step forward and get involved in a local astronomy event or two. Here's the lineup.

On February 11, the San Francisco Amateur Astronomers (SFAA) team up with the California Academy of Sciences for a new series of astronomy talks and star tours on the Living Roof of the Cal Academy. I'll be giving the talk this Thursday during the NightLife event at 7:15 pm. More information and tickets on the NightLife webpage.

On February 17, the SFAA holds its monthly meeting and lecture at the Randall Museum in San Francisco. And on February 20th they have their City Star Party and Telescope Workshop. You can dust off your old telescope and bring it out for a quick lesson on using your telescope (before the sun sets), and then enjoy stargazing at the City Star Party. This is at Lands End in San Francisco.

On February 25th and 26th, the amateur astronomy community of San Francisco bids farewell to a living legend in the field, John Dobson. John is a co-founder of the San Francisco Sidewalk Astronomers (they call what they do "urban guerilla astronomy") and the creator of the easy-to-build and easy-to-use telescopes that bear his name, Dobsonians. There will be a get together with John on Thursday 25th in the Sunset District of San Francisco, and sidewalk astronomy with John at a location to be determined in the city, to say Farewell as John moves from San Francisco to Los Angeles. I am impressed with Sidewalk Astronomers and especially with John Dobson, who had a singular vision to make telescopes accessible to anyone who wants to build one out of inexpensive parts, and to get these telescopes out on the street so everyone can appreciate the wonders of the sky and see something they hadn't seen before. I respect that.

I hope to see you at one of these events.