What’s Up in the Sky October, 2009
By Peter Burkey
If you are an early riser, this is the month for you. Three planets, Mercury, Venus, and Saturn, will display a gathering (or “conjunction”) in the morning eastern sky. If you observe for several days between October 4 and 15, you will see the three planets change position with respect to one another.
Look toward the eastern horizon about an hour before sunrise. Orient yourself by finding Venus, which will be shining like a beacon. At first Venus will be highest and brightest followed by Mercury just below it and then Saturn, to the lower left of Mercury, will be the dimmest of the three. As the days progress, Saturn will move up and to the right passing Mercury on the 8th and Venus on the 13th. On each of those days, the separation between the two planets will be less than the diameter of the full Moon.
Planets are like skaters on a roller rink, all going around a central point in the same direction at different speeds. Because of the planets’ orbits we see them in different positions from night to night, unlike the background stars that are so distant that their motions go undetected. Every now and then their motions cause them to “line up” and when they are in nearly the same direction (Saturn is, of course, much, much farther away than Mercury or Venus) it becomes easy for us to see their change in position with respect to each other. That is what is happening this month.
What you will be witnessing is an example of similar events that changed human history, for it was the study of the movement of the planets that led the early astronomers to figuring out how the soar system worked. This led to the beginnings of the scientific revolution.
I would like to invite my readers to submit questions about astronomy to me that I may answer. If you have a topic of interest or have a any questions, send me an email at firstname.lastname@example.org and I will try respond in a forthcoming column. I look forward to hearing from you. Until then keep your eyes on what’s up in the sky.
This month in history:
Oct. 1: NASA founded – 1958
Oct. 4: Space Age begins when Sputnik 1, first artificial satellite, is launched – 1957
Oct. 10: Dedication of VLA – Very Large Array (remember “Contact”?) – 1980
Oct. 14: Chuck Yeager breaks sound barrier – 1947
Oct. 22: First record of solar eclipse – 2136 BC
Oct. 26: First flyby of Saturn’s moon Titan by Cassini spacecraft – 2004
Planets this month: Jupiter dominates southern sky after dark. Mars rises after midnight and is high in the south at dawn. Saturn passes Mercury and Venus in the Eastern predawn sky.
Oct. 4: Full Moon.
Oct. 11: Last quarter Moon.
Oct. 4-15: Watch gathering of planets just above the eastern horizon one hour before dawn.
Oct. 21-22: Peak of Orionid meteors.
Oct. 18: New Moon
Oct. 25: First quarter Moon.