Sep 01

September 2007

What’s Up in the Sky September, 2007
By Peter Burkey

This month ushers in a new season of observing, the autumn constellations being some of my favorites. Overhead Cygnus, Lyra, and Aquila contain the stars, Deneb, Vega, and Altair, which form the summer triangle, Sagittarius (also known as the Teapot) dominates the south, and the Great Square of Pegasus can be seen high in the east. Skimming the treetops in the northwest is Ursa Major (the Big Dipper) which can be used as a guidepost to the constellations Bootes in the west and Ursa Minor (the Little Dipper) in the north.

Find the three stars in the handle of the Big Dipper and follow the arc to Arcturus, the bright star low in the west. In fact, Arcturus is the brightest object in the sky after Jupiter. Arcturus lies at the bottom of the kite-shaped constellation Bootes.

Return to the Big Dipper and find the two stars forming the right-hand side of the bowl. These are the pointer stars Merak and Dubhe. Follow a line drawn between them up and to the right and you will come to Polaris, the North Star.

Polaris is probably one of the most famous stars in the sky, although there are almost 50 others that appear brighter. Its fame stems from its location. If you extend the Earth’s axis straight up from the north pole, that line will point almost directly at Polaris. Thus, all the other stars appear to travel in circles around the North Star due to the Earth’s rotation. The next time you’re on a playground merry-go-round look up at the trees and you will see the same sort of motion.

This also means Polaris never rises or sets but remains fixed in the northern sky , acting as a cosmic guidepost. For centuries navigators referred to it as the Lodestar or Steering Star, seamen called it the Pivot Star and voyagers the Latin Navigatoria. Authors such as Dante, Wordsworth, Keats, and even Shakespeare make reference to it in their writings. Many ancient temples, such as the Hindu Kandariya Mahadevi Temple in India and the Great Temple of Angkor Wat in Cambodia, seem to be symbolic representations of ancient legends surrounding Polaris.

So the next time you’re admiring the North Star, think about all the people throughout history who considered it of great importance. It is but one of many cosmic connections to be found up in the sky.

This month in history:
Sept. 3: Last two lunar landings canceled by NASA – 1970
Sept. 8: Genesis spacecraft crash-lands on return to Earth – 2004
Sept. 11: Mars Global Surveyor arrives at Mars – 1997
Sept. 17: First powered flight of X-15 rocket plane – 1959
Sept. 23: Neptune discovered by J. G. Galle – 1846
Sept. 29: First launch of a satellite form Alaska – 2001

Here are this month’s viewing highlights:
Planets this month: Mercury visible before sunrise as August begins. Jupiter continues to dominate the southern sky, seen just above the star Antares in Scorpius. Mars high in ESE in predawn hours.

Sept. 3: Last-quarter Moon
Sept. 11: New Moon.
Sept. 19: First quarter Moon.
Sept. 23: Autumnal equinox – first day of fall in Northern Hemisphere.
Sept. 26: Full Moon (the Harvest Moon)