Skywatch September & October 2007
This time of this year the early evening's western sky above the Virgin Islands is dominated by a bright star-like object. It is not a star at all, but the largest of all the planets, Jupiter. If you look slightly lower in the sky you will find a bright reddish star, but not as bright as Jupiter, this is Anatares, and it marks the heart of Scorpius, the Scorpion. Scorpius is one of the few star groups that looks anything at all like its name suggests. If you look slightly to the east from Antares and even lower near the horizon, you can spot s few stars that form the Scorpion's body and long curved tail.
Look high in the sky and you will see three bright stars: Altair, Deneb and Vega. Each is in a different constellation, but since they form a large triangle that is visible during summer nights up north, they form what is known as the Summer Triangle. Brightest of the three and highest in the sky is Vega, in Lyra the Harp. To the east of Vega and closer to the eastern horizon is Deneb, the tail of Cygnus, the Swan. Slightly to the South is Altair in Aquila the Eagle.
It is difficult to see a harp or an eagle here, but perhaps you can see the Swan. Start with Deneb as the Swan's tail and then look for a string of fainter stars stretching out to the south. This is the Swan's body. Another line of faint stars at a right angle to the body form's the bird's wings. Cygnus seems to be flying south toward Jupiter and Scorpius.
If it is dark and clear you should be able to see a hazy band of light arcing across the sky from Cygnus to Scorpius. This is the Milky Way, our city of stars in the universe. Galileo was the first person to point a telescope at the Milky Way (by the way, he did not invent the telescope). When he looked through his telescope he discovered that the band of light was really an uncountable number of stars. Today we know that the band you see is light from millions and millions of stars so far away that you cannot see them as individual stars, just as a hazy band of light.
As the night goes on and the Earth turns, the planets and the stars will set in the west and others will rise in the east. If you wait until after midnight you will find the red planet Mars in the northeast. Later around 3:00 Venus will rise and until dawn overpowers the night, Venus will be the brightest object in the night sky except for the Moon. Just as night is ending you can spot Saturn, just below Venus closer to the eastern horizon.
On October 21st the Orionid meteor shower will reach its maximum. Look between midnight and dawn and you may see some 60 meteors or shooting stars per hour. What you are really seeing is pebble sized bits which are burning up as they race through the atmosphere some 50 miles overhead. The source of this cosmic debris is now almost three million miles away. Last seen in 1986, this dust is left over from Halley's Comet is presently out beyond the orbit of Uranus.
