What’s Up in the Sky – October, 2010
By Peter Burkey
It’s Jupiter time! Anyone who has been out at night lately has certainly noticed the bright object in the southeast sky. This brightest “star” is actually the planet Jupiter and it is in a great position for observing with a telescope. This month Jupiter rises just before sunset and is well up in the southern sky by the time darkness sets in. Also, we are relatively close to the planet so it appears relatively large.
When observing Jupiter, you will want to focus on two things: its surface features and its moons. Remember that Jupiter is a giant ball of gas, ten times the diameter of Earth, so when we talk about “surface features” we are referring to the patterns visible in the cloud tops. Jupiter’s atmosphere is mostly hydrogen and helium with small amounts of a few other chemicals like ammonia and methane. It is these chemicals that form the features such as the Great Red Spot (a giant atmospheric disturbance) and equatorial bands of various colors. These can be observed with a modest scope at average magnification.
I always enjoy observing the moons of Jupiter the most. After all, watching them orbit the planet from night to night was one of the pieces of evidence that helped Galileo figure out the solar system. And you can watch them disappear behind the planet or pass in front of it. If you have good eyes and a fairly decent telescope, you can even see the shadows of moons cast on the cloud tops. One of the best opportunities for that comes on the evening of October 23. Start observing about 9:30 p.m. Over the course of the next hour, you should be able to see one moon disappear behind the planet and two pass in front, each casting its shadow on the cloud tops.
As an added bonus, Uranus is also visible about two finger-widths to the left of Jupiter. With a low power eyepiece, you should be able to get them both in the same field of view.
So dust off the scope and enjoy good views of the King of the planets, one of the neatest objects up in the sky.
This month in history:
Oct. 1: First observations with 300-foot radio telescope at Green Bank, WV – 1962
Oct. 4: Space Age begins when Sputnik 1, first artificial satellite, is launched – 1957
Oct. 10: Triton, one of Neptune’s moons, is discovered by Wm. Lassell – 1846
Oct. 13: M51 (the Whirlpool Galaxy) observed by Charles Messier – 1773
Oct. 24: 199th and final flight of X-15 rocket ship – 1968
Oct. 30: STS-61A Challenger Space Shuttle launched – 1985
Planets this month: Venus, low in SW at sunset, is gone by mid-month. Jupiter dominates southeastern sky after dark. Uranus can be found in binoculars just to the upper left of Jupiter.
Oct. 7: New Moon.
Oct. 6: One-half hour before sunrise look for crescent Moon with Mercury to its left near eastern horizon.
Oct. 14: First quarter Moon.
Oct. 21-22: Peak of Orionid meteors.
Oct. 22: Full Moon
Oct. 30: Last quarter Moon.