Astronomy From Your Back Yard - 12/15 to 12/21 2010

Friday, December 17 2010 @ 03:38 pm EST

Contributed by: dgrosvold

Backyard Astronomy Extra - Total Lunar Eclipse!

By Dave Grosvold

On Saturday evening, look just to the left of the Moon a mere 2° for the delicate Pleiades star cluster. The Pleiades is a beautiful, fairly tight open cluster in Taurus that was used by Native American tribes to test the eyesight of their scouts. See if you can see more than 5 stars in the Pleiades with the naked eye. If so, then you would have qualified as a scout in the Old West. This week, you may need to use binoculars to see the Pleiades due to the overwhelming glare of the waxing gibbous Moon.

Below the Pleiades by about a fist-width is orange Aldebaran. Aldebaran is part of the Hyades star cluster, an open star cluster in Taurus that looks to most like a small “V” laying on its side in the eastern sky. Far off to the left of the Hyades shines brighter yellow Capella. On Sunday evening, the Moon is to the left of the Hyades, and just to the left of a small star named Tau Tauri (τ Tau). By Monday evening, the Moon has moved just to the left of Zeta Tauri (ζ Tau.) By now, you've realized that the Moon has taken three nights to pass from one end of Taurus to the other.

   Click image for larger view
But the REAL highlight of the week is still yet to come. On Tuesday morning, the Full Moon occurs right at the mid-point of a total lunar eclipse! Make plans now to see this last lunar eclipse of the year. The eclipse begins just after midnight in the early-morning hours of Tuesday, December 21, 2010.

The eclipse reaches its mid-point at about 2:17 AM CST Tuesday morning. The Moon will be shining brightly very high in the early-morning sky during the eclipse, in the south-southeast. By the time it reaches mid-eclipse, the Moon will be high in the southwest, and will drop into the western sky by the end of the eclipse at 4:01 AM. The best way to view this eclipse is with a pair of binoculars or a small telescope.

The dim Little Dipper (Ursa Minor) hangs just about straight down from the North Star by about 9:30 PM all this week, as if it was hung from a hook on the wall of the sky. The brighter Big Dipper (Ursa Major) is rearing upward on its handle low in the north-northeast. You can easily find Polaris, (or the North Star,) by using the two end stars of the bowl of the Big Dipper.

Venus shines with a brilliant light in the southeastern sky this week before and during dawn. Venus now rises about two hours before the first light of dawn (about 3:45 AM CST,) and rises to an altitude of about 33° before getting lost in the glare of the rising Sun. While it's till dark, look for fainter Spica well to Venus' upper right, and for Saturn above Spica. Look off about twice that distance to Venus' upper left for Arcturus. Saturn's rings have widened to 10° from edge-on, and present an interesting sight along with its larger moons in a small telescope.

Of course, Jupiter shines almost as brilliantly as Venus during the evening, high in the south-southwest. The long-absent South Equatorial Belt continues to re-form, as dark markings spread east and west around the planet from a storm that broke out in the SEB's latitude about a month ago.

Uranus is still within 2° to the left of Jupiter, and can be spotted in a small telescope. Have a look at Jupiter first, and then look for an object to the upper left of Jupiter with about the same brightness as Ganymede. Ganymede is about magnitude 5.36 where Uranus is very slightly dimmer at about magnitude 5.45. Don't confuse Uranus with the star 20 Pisces (20 Psc,) which is also the same magnitude, but it is somewhat redder, and about halfway in between Jupiter and Uranus.

Neptune is much dimmer at magnitude 7.9, and is still up in the southwest in Capricornus after dark. Look for 5th-magnuitude Mu Capricorni next to it.

Comments (1)