30 December 2011

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.

25 December 2011

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.

20 December 2011

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.

13 December 2011

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.

06 December 2011

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.