Astronomy From Your Back Yard - 10/20 to 10/26 2010
Wednesday, October 20 2010 @ 05:12 pm EDT
Contributed by: dgrosvold
By Dave Grosvold
The Full Moon occurs this week at 8:37 PM, CDT on Friday, October 22nd. The nearly full Moon washes out the sky for the entire night on Wednesday and Thursday evenings, since it will rise before sunset and will not set again until nearly dawn. However, the Moon rises about 30 minutes later each evening, so by Tuesday, October 26th, the waning gibbous Moon will not be in the sky until after 9:00 PM CDT.
Although both the bright glow of the Moon and the weather forecast don't look favorable for astronomical observing this week, you may still be able to catch a glimpse of Comet 103P/Hartley in binoculars or a small telescope. Look for it in the constellations Auriga and Gemini in the eastern sky at about 12:30 AM CDT. Whether you'll see the comet or not depends to a great degree on the quality of the sky when you make the observation.
This week, the Big Dipper asterism in Ursa Major lies level in the north-northwest after dusk, quite low, far below the bowl of the much dimmer Little Dipper (Ursa Minor).
On Thursday evening, the Great Square of Pegasus asterism is straight above the waxing gibbous Moon after dark. The Great Square is tipped on one corner and somewhat larger than your fist held at arm's length. The Great Square is actually part of two constellations - its namesake Pegasus, and Andromeda.
Mars is getting dimmer at magnitude 1.5, which is still fairly bright as astronomical objects go. Mars continues to linger very low in the southwest right after sunset.
Even with the moon glow, bright Jupiter is an easy target in the constellation Picses. Jupiter is still within its first month past opposition, and has just passed a very close approach to Earth, — perfectly positioned for viewing mid-way up the east-southeastern sky, reaching its highest point at about 11:00 PM.
On Saturday, October 23rd, see if you can catch the tiny black shadows of both Ganymede and Europa as they pass across Jupiter, from 8:40 to 10:04 PM CDT.
Saturn is back as a morning planet, just emerging from the sunrise glow. Look for it in the constellation Virgo, very low in the east about an hour before sunrise. It's within 1° of fainter Gamma Virginis.
Neptune, at magnitude 7.8 in Capricornus, is still highest in the south about an hour after sunset. With the expected sky conditions this week, Neptune will be a difficult target. You will need a small telescope to catch it.