I hope you had a chance to enjoy the harvest full moon last week over Everett. As nice as it was I’m glad it’s over with. Now we can get back to some real stargazing without the lunar whitewashing and see the mythological features and stories in the late summer heavens.
Constellations that allegedly make pictures in the sky have been dreamed up by humankind throughout the centuries. Depending on the culture constellations can represent all kinds of things. They can be people, monsters, gods, celestial instruments, and much more. Back in 1920s, the International Astronomical Union came up with a standard list of 88 constellations, most from Greek and Roman mythology tales. Nine of these constellations are birds. Aquila the Eagle is one of the best of the bird constellations and this month it’s flying high in the southern sky.
The best way to find Aquila is to use the handy tool, or asterism, known as the “Summer Triangle.” Look for the three brightest stars you can see high in the southern sky in the early evening this time of year and that’s it. Each of the three stars is the brightest in their respective constellations. The brightest star in the Summer Triangle is Vega which is also the brightest star in the constellation Lyra the Harp. If you’re facing south Vega will be on the upper right hand corner of the Summer Triangle. On the upper left is Deneb, the brightest star in the Cygnus the Swan. The star on the bottom of the Summer Triangle is Altair, the brightest shiner in Aquila the Eagle.
As you can see in the diagram, Altair is on the upper left hand corner of a large diamond that without too much imagination outlines the wingspan of the heavenly but headless eagle. Altair is at the heart of the eagle. Off the lower right corner of the diamond star look for a faint line of stars that outlines the tail of Aquila. The head of the eagle is on the upper left side of Altair, but you’ll really have to put your imagination in overdrive to see it because there are no real stars in that part of the constellation to help you out.
Altair is the 12th brightest star in the sky and it’s relatively close (16 light years or about 97 trillion miles away). Because it’s so close astronomers know quite a bit about it. Altair is almost 11/2 million miles in diameter, twice as large as our sun but cranking out a lot more light than our home star (more than nine times as much).
The most fascinating discovery made about Altair is its dizzying spin. That star takes less than seven hours to make a full rotation. Altair’s rotational speed at its equator is 160 miles per second. By comparison our sun takes about 25 days for one rotation. Altair, like all other stars, is a big ball of gas and its rapid spin causes Altair to bulge out at its equator. It’s so extreme that Altair is twice as wide from side to side as it is from top to bottom. It’s shaped more like an egg.
Scan your telescope all around Aquila and you’ll find some nice little star clusters of young stars, but the best eye candy through a small to moderate telescope is Messier object 11, just off the tail of Aquila. Actually M11, as it’s referred, is technically in a small adjacent constellation called Scutum the Shield. M11 is a beautiful open cluster of almost 3,000 young stars about 6,000 light years or 35 thousand trillion miles away. These are young stars (about 220 million years old). M11 has a nickname — “Wild Duck Cluster” — because many people see it as a flock of flying ducks. Crank up your imagination to see that image.
Mike Lynch, an amateur astronomer and professional meteorologist for WCCO Radio in Minneapolis, is author of “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications and available at www.adventurepublications.net
Talk to us
> Give us your news tips.
> Send us a letter to the editor.
> More Herald contact information.
