Summer Triangle guides way

Constellations, otherwise known as groups of stars that allegedly make pictures in the sky, have been dreamed up by humankind throughout the centuries and depending on the culture, they can be all kinds of things.

Constellations can represent people, monsters, gods, instruments and much more. Back in 1922, the International Astronomical Union came up with a standard list of 88 constellations, most from Greek and Roman mythology.

Eight of these made up constellations are birds. Aquila the Eagle is one of the best of the bird constellations. In these cooler October skies, it's soaring the western sky in the early evening.

The best way to find Aquila in our Butler sky is to use the handy tool known as the Summer Triangle that, believe or not, is still easily found even though it's officially out of season.

Just as in pro sports, there's a lot of season overlap. Anyway, just look for the three brightest stars you can see high in the southwest sky in the early evening and that's it, the Summer Triangle.

Each of these stars is the brightest in its own constellation. The highest and brightest star is Vega, the brightest star in the constellation Lyra the Harp.

On the lower left is Deneb, the brightest star in the Cygnus the Swan. The star on the lower right of the Summer Triangle is Altair, the brightest shiner in Aquila the Eagle.

Altair is on the left hand point of a large vertical diamond that, without too much imagination, outlines the wingspan of the heavenly eagle.

Altair is at the heart of the eagle. To the right of the star on the right side of the diamond, you'll see a faint line of stars that outline the tail of Aquila. The head of the eagle is on the left side of Altair, but you'll have to rely totally on your imagination to see it. There are no real stars in that part of Aquila to help you.

Altair is the 12th brightest star in the sky and it's relatively close, only 16 light-years or about 97 trillion miles away. Believe it or not, that's a lot closer than most stars we see in the night sky.

Because it's so close, astronomers know quite a bit about it. Altair is almost 1.5 million miles in diameter, twice as large as our sun but cranking out a lot more light than our home star, more than 10 times as much.

The most fascinating discovery made about Altair is that it has a bulging waistline. The Palomar observatory in California discovered that Altair's diameter is more than 20 percent larger along its equator than from pole to pole.

Further observations revealed that Altair is rapidly spinning on its axis at the rate of one full rotation in less than 9 hours. By comparison, our sun takes more or less an entire month for one rotation.

Altair, like all other stars, is basically a big ball of gas, so it's rapid spinning and centrifugal force, the same force you feel on a fast merry-go-round, causes Altair to bulge out at its equator something fierce.

Scan your telescope all around Aquila and you'll find some nice little 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 to, is technically in a small adjacent constellation called Scutum the Shield. M11 is a beautiful open cluster of almost 3,000 stars more than 6,000 light years, or 35 thousand trillion miles away!

These are young stars only about 220 million years old, which is considered infancy for stellar age. M11 has a nickname, the "Wild Duck Cluster," because many people see it as a flock of flying ducks. Crank up your imagination to see that image!

The main Greek mythology about Aquila has the eagle as Zeus' faithful pet. Zeus, of course, was the king of the gods of Mount Olympus.

Aquila accomplished many missions for Zeus, including torturing enemies and delivering thunderbolts. The eagle's main claim to fame was his capture of the Trojan shepherd boy Ganymede, son of King Tros, to become the cupbearer of the gods on Olympus.

Zeus wanted the finest young man he could find to become basically the bartender of the gods. He sent Aquila on a reconnaissance mission where he discovered Ganymede, plucked him up by the shoulders, and delivered him to Zeus.

Ganymede proved to be worthy of his forced labor and happy hour was great on Mount Olympus ever after. Zeus rewarded his faithful eagle by placing him among the stars as the constellation we now see high in the southeast sky.

Incidentally, it's no coincidence that one of the planet Jupiter's largest moons is named Ganymede, since Jupiter is the Roman name for Zeus.

Jupiter is also easily available tonight in the low southern skies. It's by far the brightest starlike object in that part of the sky. With just a small telescope or even a good pair of binoculars, you can see up to four of Jupiter's moons at one time, looking like little stars on either side of Jupiter's disk.

One of them is Ganymede, not only the largest moon of Jupiter but the largest moon in our solar system. It's even bigger than the planet Mercury.

Close encounters

Monday night the new crescent moon will be parked just above and to left of the fairly bright star Antares in the early evening low southwestern sky.

Antares is 600 light-years away with just one light-year equaling nearly 6 trillion miles. Even with the naked eye you can see it's a dark reddish star.

Antares is astronomically a super red giant star 700 times the diameter of our sun. It's so big that if it were positioned in the center of our solar system in place of the sun, the planets Mercury, Venus, Earth, and Mars would all be living inside Antares!

Also the super bright star in southeast sky is Jupiter, and it's the closest it's been to Earth since 1963!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book "Pennsylvania Starwatch," available at bookstores and at is website www.lynchandthestars.com.