The Moon: where is it going to rise tonight?

Moonrise in San Francisco

An old friend, Scott in San Francisco, posted a question on Facebook and it caught my attention. He illustrated a quandary that he faced when observing the moonrise in San Francisco on two consecutive nights and wondered why the two locations were so different. Here is what he wrote: "I am puzzled ... Can someone explain how the moon changes its position so radically in one day? I created a hand drawing of the moon, its location, and time as it rose over the San Francisco skyline the last two nights." There are two (well actually three) factors at work here.

Before we dive into the specific factors, let's review the basics. The moon, like the sun, rises in the east and sets in the west, but of course the precise point of sunrise varies throughout the year. The sun rises either north of east in the summer when the days are longer, or south of east in the winter when the days are shorter. The full moon, which Scott was observing when he sketched the images last month, has an opposite behavior compared to the sun ... that is, the moon is in the opposite part of the sky compared to the sun and as such, in the winter the moon rises north of east (when the full moon nights are longer) and south of east in the summer (when the full moon nights are shorter).

In addition to that macro change in the position of the moonrise compared to sunrise throughout a year, there are daily changes to the position of the moonrise. The moon, being much closer to Earth than the sun, moves rapidly in its 29 day orbit around the Earth and from one day to the next is approximately 12 degrees further eastward in comparison to its location the night before. That is the main reason that a rising moon rises approximately one hour later each evening, and the primary factor that is illustrated in the drawing above. The Earth has to turn more to get to the place where the moon has moved, in this case from 8:00 pm to 9:00 pm/.

Moonrise position changing

But there is a subtle secondary effect that Scott captured in his sketch. That is that the location of moonrise is quite a bit shifted on the horizon. In this case, it is to the south from one day to the next, not just a later moonrise time but also a point on the horizon that is south of the previous day. What is happening here is that the moon's path around the Earth is quite similar to the sun's path around the sky and that is a path that follows the zodiac band around the sky, something also called the ecliptic. Because the moon follows this path, and in this special circumstance in which a full moon is observed on successive nights, the winter full moon appears to rise further and further south on consecutive nights until it finally moves to last quarter moon phase and then it will resume its travels northward (north of east) as it rises late each night. In fact, the moon is simply moving across the known Zodiac constellations of Virgo, then Libra (see image on left), and eventually Scorpius and Sagittarius, all of which are low on the horizon and low on the ecliptic, and therefore are part of the reason why the moon rises further and further south of east on consecutive nights in the winter. The image shows how the moon moves across the Zodiac from night to night, but it will take some creativity to juxtapose this on the eastern horizon to fully understand why the moon is further south of east on consecutive nights. Think about it. It requires some big picture thinking.

There is a third factor for the change in the location of moonrise on consecutive nights which is based on the moon's orbital inclination, but that requires fairly expert knowledge of celestial mechanics to fully comprehend so we will save that for another time ... or a star party.

Today is the full moon, March 9th, 2020. You can try to reproduce Scott's experiment now, looking closely at the eastern horizon and locating landmarks where you can spot the moonrise on consecutive evenings. For the next 3 or 4 evenings the moon will rise about an hour later each evening, and also will rise at a point further to the south of east compared to the night before.

I wish you clear skies and happy viewing.

Total Lunar Eclipse of September 27, 2015 - in San Francisco!

Sunday September 27 we experience a total lunar eclipse visible from North America and of course here in San Francisco. This eclipse features the Moon passing nearly through the center of Earth's shadow, meaning that the Moon will remain in eclipse for over an hour and should be fairly dark, at least on one side. And from San Francisco we will see the unique situation of a Moonrise that is of a nearly fully eclipsed Moon, an unusual sight.

Total Lunar Eclipse - geometry

The eclipse takes several hours to occur, from first touch of the Earth's penumbral shadow to last contact, but the main part of the eclipse is the most exciting part, that of 'Totality' when the Moon's surface is fully darkened by the shadow of the Earth. From the west coast, totality starts at 7:13 pm and ends at 8:22 pm. Given that the Sun sets at 7:01 pm, the local conditions should lead to a very interesting Moonrise (just moments after the sunset) with nearly all of the Moon eclipsed.

The San Francisco Amateur Astronomers (SFAA) will be set up at Pier 15 along San Francisco's Embarcadero (just next to the Exploratorium) for public viewing, as the rising Moon should make a lovely picture just above Treasure Island and the San Francisco Bay. We will be there from 6:30 until 8:30 pm.

Here are several excellent resources on the eclipse:

EarthSky: http://earthsky.org/?p=51212

Wikipedia: https://en.wikipedia.org/wiki/September_2015_lunar_eclipse

NASA: http://eclipse.gsfc.nasa.gov/lunar.html 

Jupiter & Venus Conjunction – Closest Approach Since 2000

After the Moon, the two brightest objects in the night sky are the planets Venus and Jupiter. Venus is a close neighbor and a very reflective planet, dominating morning and evening skies with its brilliant white shimmer against the changing colors of the dawn or dusk sky. Jupiter is the giant planet of the Solar System and despite its distance, is a bold and bright object for us to enjoy, especially in a telescope or binoculars.

Venus & Jupiter Conjunction

These two planets, like all of the objects in the Solar System, gradually change their position with respect to the background stars from day to day. All of the objects in the Solar System move along a common path across the sky, the Ecliptic. And from time to time these objects line up and create beautiful patterns and visually stunning sights.

On the morning of Monday August 18^th (from North America), we will see Venus and Jupiter in a conjunction, a close alignment of the two bodies from our Earthbound point of view. The two will be in the east just before sunrise, so you’ll have to get up early to see this, but it will be rewarding. The two will be less than the Moon’s width apart, and given their bright nature, the pairing should be spectacular. Through binoculars, you will also be able to see a lovely star cluster, the Beehive Cluster, in the background of stars, as Jupiter and Venus will be in the constellation Cancer and passing through the Beehive.

The image (courtesy of Sky & Telescope) shows where to look. From San Francisco, sunrise will be at 6:30 am and the Venus-Jupiter pair will rise at 5:00 am, so you will need a good northeastern horizon to see the pairing, and the 30 minute window starting at 5:00 will provide the best dark-sky viewing conditions as the glare of dawn will start to interfere by 5:30.

You can find an excellent write up on the conjunction on Sky & Telescope's website. 

Urban Astronomy video from the Exploratorium

The Exploratorium is one of the finest science museums anywhere, a place I've found exciting and fun to visit for years. They bring science 'hands-on' to the visitor and provide endless learning moments where the visitor can discover something new and unique about science in a fun and engaged way. They have been building a video series for some time now, called "Science In The City" and I was recently invited to be a contributor to their feature on Urban Astronomy.

Producer Jim Granato created a 10-minute piece that brings to life the ways in which one can experience astronomy even in the confines of a big city like San Francisco, a theme near and dear to my heart. I really enjoyed how Jim put together sequences of Adam Esposito of the Exploratorium showing off the night sky right on the waterfront of the City, and how people react when they get a close up look at heavenly bodies. I am a huge fan of John Dobson and what he did to bring low-cost telescopes to the world, and appreciate what the Chabot Space & Science Center bring to the masses with their array of telescopes, star parties and telescope-making workshops. And I enjoyed contributing my own opinions and perspectives on urban astronomy to the video, sharing some thoughts on how to enjoy the night sky right from your own backyard.

Click here to watch the video. It's a refreshing look at the subject.

Venus and the Crescent Moon Pair Up

Moon and Venus pair up

Sunday September 8th will be a good day to go to the beach (or anywhere with a good western horizon) to see a great alignment of brilliant Venus and a young thin crescent Moon hovering above the horizon minutes after sunset. The two will be a beautiful pair for the hour after sunset (7:30 pm here in San Francisco) and as the sky darkens in the minutes after sunset, Earthshine on the Moon should be outstanding. The skies in the San Franisco Bay Area are at their best of the year, clear and calm. Can't wait to look at this!

EarthSky recommends that you use the Moon to help you find Venus during the daytime. Yes, you can see the brightest celestial objects in the middle of a sunny day if you know where to look. I think it's quite cool to spot the shiny dot of Venus hanging in the bright blue sky. It's a real challenge to find, but worth the search. Best of luck with that, and if you don't find Venus in the day, you'll certainly find it after sunset.

Clear Skies!

Amateur astronomers often sign off an email or message with the phrase "Clear Skies" because anyone interested in enjoying the night sky needs to have a clear sky to start with. I often close blog posts on this blog with the phrase "Clear Skies!" as a kind of wishful thinking and good luck charm.

Right now in San Francisco, I need all the good luck I can get. The coastal weather pattern each summer ensures that clear skies will be rare indeed, especially in the Outer Richmond district where I live. So I have had precious few viewing opportunities from my own backyard this summer, and the San Francisco Amateur Astronomers have been forced to cancel most of their "City Star Parties" that take place near Lands End on the western side of the city, due to fog.

Venus and the sunset sky

When we get the rare clear sky, or when I am in another part of the Bay Area and am enjoying a stunning view of the western horizon just after sunset, I am reminded why I love astronomy; the beautiful changing color of the sunset sky, and the gradual transition into night, and the dazzling light of Venus in the west, all combine to motivate me to look up in the sky, and more than ever, I appreciate the clear skies that usually are available here in the Bay Area.

So to all of you, I wish you "Clear Skies" and a warm night somewhere this summer to enjoy the heavens.

Image courtesy Pete Lawrence.

KGO Broadcast - February 16, 2013

Last Saturday I had a fun experience: joining KGO 810 Talk Radio in San Francisco for a one-hour broadcast. Greg Gory invited me to stop by and talk about asteroids, meteors, fireballs and many other astronomy topics, and we had a fine time doing all of that and more! We entertained calls from listeners and ended the show on a high note, discussing why we go into space and explore in the first place. Click here to listen.

Viewing the Night Sky in City Settings

I am often asked "can you really see any stars in the big city?" Living in San Francisco, this is a reasonable question, since we have a great deal of light pollution in our region, and the sky is often glowing, seemingly obliterating all but the brightest of celestial objects.

Night Sky in an Urban Setting

My answer is always "of course you can see stars and constellations in the City," but it takes some discipline to make the most of urban star gazing. Here are a few factors to consider. First and easiest, you need to give yourself some time for your eyes to adapt to the darkness outside, since most urban dwellers live in well-lit environments, and need to allow enough time for their eyes to adapt before they can see anything. Spending 10 minutes in darkness should be plenty to get things going.

Second and somewhat more challenging, you can see a lot more in a city setting if you view the sky from a dark spot. I don't mean that you have to drive out of town to see stars, but rather you simply need to find a dark spot, the darkest one you can find where you live or a short walk from where you live. For example, in my backyard in San Francisco, there are spots where I can sit or lie to see stars where the light of nearby streetlights illuminates the space, and other spots where I am in the 'shade' of the streetlights. That will make a big difference, since my eyes will respond better to the faint stars above me if I am in the darkest possible spot in my backyard.

Third, you need the local weather conditions to help you out. Lower humidity is good for stargazing, since moisture in the air picks up and reflects light from urban areas, making the sky 'glow' which diminishes the view through the atmosphere out to the heavens above. Similar to humidity, there are other factors that make the night sky more or less transparent. I recommend to use the Clear Sky Chart as a guide to direct you when the skies are going to be optimal for stargazing, whether you do so from the City or the suburbs or the country. There is also an iPhone app for the Clear Sky Chart.

Finally, some kind of optics helps, even in bright city settings. A simple pair of binoculars or a telescope will reveal much more of the sky, even when there is light pollution. Very faint objects will be invisible, but many objects that are not visible to the naked eye will still be present with magnification and good quality optics.

Most important are cloud-free skies, and the patience and commitment to enjoy the night sky.

Perseid Meteor Shower 2012

The big meteor shower of the year, the Perseids, peaks this weekend and promises a good show for all who can find dark skies and have the patience to enjoy them. The Moon will generally cooperate with viewers since it will only interfere very late into the night, and even then will only cast a small amount of glare on an otherwise exciting event.

The Perseids are a regular meteor shower that peak over one or two days each August as the Earth plunges into a stream of particles from the comet Swift-Tuttle. As we impact these particles at tens of thousands of miles per hour, we enjoy a spectacle of shooting stars darting across our night sky, sometimes one per minute, sometimes less or even sometimes more. Your ability to see more meteors depends upon three things: (a) dark sky, (b) dark adaptation, and (c) lateness of the night. The darker the sky, the fainter the meteors you will see. The longer you are in your dark environment, the better your eyes will adapt to the dark and enable you to see fainter objects. And finally, later in the night the Earth is intercepting more and more meteors, right up until the first light of dawn.

The shower peaks on Saturday night August 11th and Sunday night August 12th. Your best bet in the San Francisco Bay Area will be locations away from city lights with good views across the entire sky, but in particular with a good eastern horizon.

EarthSky has a helpful article about the Perseids. From EarthSky: "They radiate from a point in the constellation Perseus the Hero. You don’t need to know Perseus to watch the shower because the meteors appear in all parts of the sky. The Perseids are considered by many people to be the year’s best shower, and often peak at 50 or more meteors per hour in a dark sky."

Summer looking South-West

Now that the summer constellations have fully emerged, I am enjoying the sparkling views at night as I look from one horizon to the next. Last week I focused on the eastern horizon while conducting a Star Party at Mt. Tam, but the next night I was in my yard viewing the south-western sky, and was so amazed by the view.

South-West Sky in June

In early summer, Leo is diving down toward the western horizon, with the familiar lion shape almost face-down. Mars has been steadily moving eastward across the ecliptic, from its springtime position near Regulus in Leo, now more than half-way to Spica in Virgo and a lineup with Saturn in August.

Bright Spica and Regulus, with the planets Saturn and Mars between them, create a beautiful string of bright shiny objects low along the south-west, and from my backyard in San Francisco, the view to the south-west is fairly dark, so everything was just right in the sky as I gazed in that direction. To the left (east) Scorpius is coming up into view and later in the evening dominates the southern horizon -- but I'll have more on that in a future post. And directly above, you can enjoy the dazzling star Arcturus and the lovely Northern Crown just nearby (Corona Borealis - - read more here). Just below Virgo is the easy-to-spot constellation Corvus. The sky is full of wonder, and summer weather makes it more fun and relaxing to see the sky. Wherever travels take you this summer, dedicate an evening to star gazing and reward your senses with the beauty of the heavens.

Image courtesy of SkySafari.

Transit of Venus on June 5

It's showtime! 8 years ago, the planet Venus passed in front of the Sun, and now it's time for the second of the pair of transits before a 105-year break. The view from San Francisco and the west coast of the US will be very fine, with the event visible in the western sky starting around 3:00 pm until sunset.

I spoke with Ben Trefny of KALW radio about the Transit of Venus. You can listen to it here. 

Much is being written about this transit. It fits into the category of 'unique and rare astronomical events' that are special and worthwhile to see if only for the rarity of the event. Venus makes two transits of the Sun every 100+ years, and the last one of this pair (8 years ago) was not visible in San Francisco, so Tuesday June 5th is a special opportunity to see this event. The website transitofvenus.org is an outstanding resource, as is Sky & Telescope with their historical writeup of past transits. Safe viewing tips can be found here on EarthSky.

I am going to take part at an event co-sponsored by the San Francisco Amateur Astronomers and NASA Ames in Mountain View. And there are many more places to see the transit with amateur and professional astronomers around the San Francisco Bay Area - thanks to this list from the AANC. However, if you don't get out to an event, no need to worry. You won't need a telescope to see this, just eye protection as you would use during any solar viewing, and you will easily spot the disk of Venus moving slowly across the Sun's surface. Make the effort; the next chance will be in 2117.

Image courtesy of Wikipedia.

Get Involved: Dark Skies

As an Urban Astronomer, I am enthusiastic about astronomy even in the light-polluted urban centers of the world, including my own city of San Francisco. I write this blog for many reasons, one of which is to remind city dwellers that there is still plenty to see in the night sky. Right here in San Francisco, there are ways to view the sky in a dark spot, away from streetlights and brightly-lit areas of the City, and see quite a bit of the night sky. Mainly you just need patience to let your eyes dark adapt your location, and before you know it you can find quite a few stars and constellations.

Over the past weeks, I was traveling in and around Flagstaff, AZ, the World's First International Dark Sky City. Flagstaff is a medium-size city of about 60,000 people, but through smart street lighting, has reduced its light output considerably. While visiting Lowell Observatory on a hill above Flagstaff, you could see the city lights below, but it was not like any other I had seen. Clearly there was light from the city, but it was subdued, not shining up in the sky but rather shining down onto the streets and public spaces. That is Smart Lighting!

There is a global organization called the International Dark-Sky Association that provides advocacy and education to support communities and municipalities around the world to learn about smart lighting and preservation of dark skies. I applaud their efforts and their mission. Locally in San Francisco fellow SFAA member Dave Goggin has organized a list and invites participation in San Francisco discussions about lighting.

What can you do in your community to preserve dark skies? I am sure the Dark Sky Association would welcome your participation. It's a very grass roots thing. Here is an article about an individual in San Clemente starting a movement there. Get inspired!

Resources for Urban Astronomers

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

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.

Quadrantid Meteor Shower 2012 - peaks January 3-4

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

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

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

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

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.

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.