Gentle autumn brings change in nightly sky


October 12, 2010

Editor's note: Jack Horkheimer, executive director of the Miami Museum of Science and Space Transit Planetarium for 35 years, died in Miami of a breathing ailment on Aug. 20. He was 72 years old. Horkheimer created and hosted "Star Gazer", a weekly public television program that encouraged naked eye astronomy and ran for more than three decades on stations across the world. The Triton has published scripts from his shows for the past six years. This show was produced before he died. -- Lucy Reed

Whenever the seasons change on Earth, so too do the stars change overhead, thus the phrase "the stars of the season." That phrase usually refers to the major stars and star groups that reach their highest position above the horizon in mid-evening, so because autumn officially began on Sept. 22, we could already see a change in the stars overhead.

Any night during the first two weeks of October around 10 p.m., look just west of overhead and you will see the three bright stars that make up the points of the Summer Triangle: the brightest being Vega in the constellation Lyra the Harp, the second brightest, Altair in Aquila the Eagle, the third brightest being Deneb in Cygnus the Swan.

During the first week of summer at the end of June, the Summer Triangle was just rising in the east at 10 p.m. But if you went out at 10 p.m. each successive week all summer long you would have noticed that the Summer Triangle was a little bit higher in the sky each week. By the end of August, was almost directly overhead at 10 p.m.

If you looked to the northeast at 10 p.m. at the end of August, you would have noticed that the autumn constellation Cassiopeia, a group of five stars that, when connected by lines, looks like the letter "m" or "w" on its side, was just rising.

And if you looked just above and east of Cassiopeia you would have also seen four dimmer stars that, if you draw lines between them, make up a great rectangle or square called the Autumn Square or the Great Square of Pegasus, because it is part of the huge constellation Pegasus, the winged horse.

Then, if you went out each successive week in September at 10 p.m., you would have noticed that the Summer Triangle was slowly moving past overhead and beginning its descent toward the western horizon while the autumn square of Pegasus was ascending higher and higher in the east, so that by the first two weeks of October it is almost overhead at 10 p.m. instead of the Triangle.

I think it is rather poetic that the three blazing hot stars that make up the Summer Triangle are replaced by the four much dimmer and softer stars of the Autumn Square because autumn is, after all, the softest and gentlest season of the year.

Do go out and see for yourself how the heavens above have their own seasons just as our Earth has below. Look first for the Summer Triangle west of overhead beginning its descent toward the western horizon, then look for autumn's Cassiopeia in the northeast, and finally almost overhead, autumn's Great Square, which the ancient Babylonians believed was the doorway to paradise.

And if indeed autumn is a visual paradise on Earth, how appropriate that this lovely portal to a cosmic paradise heralds in the loveliest of seasons.

Keep looking up.For more information about stars, visit www.jackstargazer.com.