Week of June 1-7, 2014

As springtime slips away and summertime again descends upon us in the Northern Hemisphere of planet Earth, we can see low in the eastern sky after dark one of the most famous star groupings of the upcoming season. Astronomers know it as the Summer Triangle because ... well, it's a triangle that appears in the summer.

The Summer Triangle is not actually a constellation but an asterism, a group of stars that we can trace to resemble something familiar. In fact, each of its three bright stars — Vega, Deneb and Altair — is the brightest of three separate constellations. But that doesn't mean that the asterism has been passed over by early storytellers.

For example, in an ancient Chinese love tale, Deneb represents the magpie bridge over the Milky Way which allows the separated lovers Altair and Vega to be reunited on only one summer night each year.

The brightest of the stellar trio — and highest in the sky — is Vega, the most prominent star in the tiny constellation of Lyra, the harp. This brilliant white star has a diameter and mass some three times greater than our sun, and produces about 50 times more power than our star. As a result, astronomers believe that Vega will likely exhaust its fuel in only one-tenth the time, making its expected life span only about one billion years.

Movie buffs may remember this star as the one from which radio astronomers detected intelligent signals in the fictional motion picture "Contact." I guess that would make Vega ... heh heh ... a movie star!

The southeasternmost of the three stars is Altair, the brightest in the constellation of Aquila, the eagle. Its name comes from the Arabic "al-Nasr al-Ta'ir," meaning in English "the flying eagle." Altair lies about 96 trillion miles (17 light years) from us. In other words, its light has been traveling through space for roughly 17 years, and its photons of light that strike our eyes tonight have been traveling through space since 1997.

Not only is Altair one of the nearest stars in our sky, it's also one of the most rapidly rotating. Astronomers have measured that this white star spins once every 6.5 hours, completing nearly four rotations for every one made by our own planet. As a result of this rapid spin, Altair is most likely so flattened by centrifugal force that it would appear more like an egg than a sphere.

Finally, farthest to the north, lies Deneb, located in the tail of the great swan Cygnus. Deneb lies some 9,000 trillion miles (about 1,500 light years) from us — so far that we see it as it appeared in the sixth century. The light that leaves the star tonight won't arrive here until around the year 3514.

Deneb is not only the brightest star in Cygnus, it's one of the most luminous in our entire galaxy. From its distance of almost 1,500 light years, Deneb shines with a luminosity equivalent to more than 261,000 suns. In fact, it generates more light in just one day than our sun has since the days of Marco Polo at the end of the 13th century!

Visit Dennis Mammana at www.dennismammana.com. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.