Everything you always wanted to know about astronomy
September
By Bruce Dennis

Jupiter shines brightly in the West at Sunset. Later, Mars will rise in the East, getting brighter as the months go by. At the end of the night for most of the month, Saturn will get closer and closer to Venus. Venus is very bright, and is clearly our morning 'star'.

Mercury is very hard to see, but can be spotted about a half hour after Sunset low in the West, just above the horizon. It will be directly West during the first part of September, and slightly South of that point just before October. Look very low next to the horizon on clear nights. On September 21st, just above the West-Southwest horizon, Mercury and a star, Spica, will be almost touching each other. This occurs about 30 minutes after Sunset. Check it out with your binoculars.

As the sky darkens at night, it's fun to spot (on a clear night) the first stars or planets that appear. When I was a kid, "I see the first star, the first star sees me… ." Shooting stars (a plural noun) were something special. Oh well - we can't turn back the clock. Jupiter is the first bright spot we see as the sky gets dark. It'll set by 10:00 by the end of September. Since the sky really doesn't get dark enough (because of Daylight Savings) to do much observing until about 9:00, this doesn't give us much time to observe. Don't waste any time!

Mars will rise around 11 PM for most of the month. It will be large enough for you to observe some surface features with a good telescope. Make sure you're in a dark place and the air is stable. Shifting warm and cold air masses, dirt, smoke, fog, haze, and light pollution are the astronomer's worst problems. Try it - you might get lucky. Mars will continue to grow and get brighter. You'll really be impressed with Mars when December arrives!

Venus will rise about 1 ? hours before the Sun in the East during the first week of September. By the last week of the month, it'll rise a full 3 ? hours before the Sun. At that time (the end of September), Venus will be at least 10 times brighter than Jupiter. Venus will be the brightest object (except for the Moon) in the sky. It is at its maximum brightness. It is so bright that you will be able to see it in the daytime sky. Try it on a nonfoggy, non-cloudy, clear morning. While Venus is going away from us during the month (its orbit is quickly bringing it to the other side of the Sun) it will increase its phase from a giant sliver to a small 1/3 ball. Use a small telescope when viewing these phases.

To the lower left of Venus is Saturn. Saturn is much smaller and dimmer, and about 15 degrees (the size of your spread hand at the end of your outstretched arm) from Venus. By the month's end, Saturn and Venus are much closer together. Saturn has the least tilt it has had in 9 years, and its rings are closing. This gives it less reflective surface pointed toward the Earth, so it looks dimmer.

If you happen to be in Central or South America or Antarctica on the morning of September 11th, temporarily interrupt your prayers for the anniversary of the Twin Tower's demise and observe the partial eclipse of the Sun. Be sure to protect your eyes - never look directly at the Sun. For local predictions, go to http://sunearth.gsfc.nasa.gov/e clipse/OH/OH2007.html .

On September 3rd, a half Moon passes in front of the Pleiades at 1 AM. On September 9th at about 45 minutes before Sunrise, Saturn is about a fist-width below a thin crescent Moon. On the 18th, at about an hour after Sunset, Jupiter is a handspread above a partial Moon. On September 23rd, the direct rays of the Sun pass over the equator, marking the first day of Autumn for the Northern Hemisphere. Happy viewing.

Bruce Dennis is a retired science teacher from Haverling High School.