Total Lunar Eclipse 2011 - in San Francisco

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

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

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

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

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

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

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

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.