31 August 2011

Big Astronomy Events in 2011 and 2012

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.

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!

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.

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.

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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.

21 August 2011

Seeing the Milky Way in City Skies

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.

06 August 2011

Perseid Meteor Shower 2011

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.