August 18, 2006
Just before the eastern sky brightens with sunrise, three planets and the waning crescent moon join the starry twilight tapestry. Then, as the bright stars of Gemini and Orion fade with oncoming dawn, the planets rise and shine.
About 45 minutes before sunrise on Aug. 20 to 22 the planets Venus, Mercury and Saturn dance on the ecliptic -- the plane of Earth's orbit and the imaginary line tracing it in the sky. The sun, moon and planets appear to move along this line.
Venus, rising an hour and a half before sunrise, is the easiest to see in the morning sky. Two hundred forty-one million kilometers (150 million miles) distant, Venus is Earth-sized.
Mercury, at a distance of 183 million kilometers (114 million miles), is the fastest and smallest of the inner planets and appears brighter than the more distant Saturn.
Saturn, 1,517 million kilometers (943 million miles) distant, was at conjunction with the sun just two weeks ago and now rises nearly an hour before sunrise.
On Aug. 26 and 27, Saturn pairs with much brighter Venus at dawn.
What other planets can we see in late August? Mars sets 45 minutes after sunset by month's end but is lost from view in the twilight, while brilliant Jupiter remains prominent as the only planet visible for a few hours during the late August evenings.