September's night sky has beautiful planets and of course, the harvest moon in the middle of the month.
Mercury, Venus, and Mars Together at Dusk
The three planets closest to Earth are still hanging together after sunset, low in the western sky. Venus should be easy to see at magnitude -3.9, but the others will be a trick. Once the sun is below the horizon you can use a pair of binoculars to scout out the others in the faint rosy light of sunset. Venus starts the month closer to Mercury, which shines more brightly than Mars, but the second planet from the sun soon zooms toward Mars.
On September 1, the 5% lit crescent moon will lie not far from the trio. The date of the closest approach between Venus and Mars comes on September 11. Venus and Mars lie a mere 18 arcminutes apart, which is less than a half degree.
Fall and the Harvest Moon
The September equinox occurs at 11:44 am EDT. This marks the first day of fall in the Northern Hemisphere and the start of spring in the Southern Hemisphere. Find the exact positions of east and west where you live on this day. At sunrise the sun will appear above the horizon directly east and will disappear at sunset straight west. Following this date, you can watch the sun quickly set farther southwest on the horizon each night.
This year the Harvest Moon, the closest full moon to the Northern Hemisphere's autumn equinox, occurs on September 15 at 5:13 am EDT. On both September 14 and 15 the moon will appear more than 99 percent lit as it rises above the horizon.
Jupiter Rules the Night Sky
For many months now, Jupiter has been the bright "star" in the southern sky. Jupiter's presence continues to dominate because the brighter Venus sets so early yet. Jupiter shines at magnitude -2.4 and lies in Sagittarius just above the handle of the teapot. On September 9, the view is picture-worthy when the moon joins our solar system's largest planet.
Jupiter will spend the rest of the year in Sagittarius the Archer. This constellation is a great place to observe star clusters and nebulae because it lies in the direction of the thickest part of the Milky Way. In fact, just above the spout of the teapot lies the center of our galaxy. Unseen to backyard telescopes, a massive black hole looms there behind the sparkling clusters of stars.
September 2008 offers up many excellent stargazing opportunities just after sunset. Next month, get ready for Venus to rise higher into the sky, where it will eventually meet up with Jupiter in December.
