Looking Up: 'Kite flying' on a spring night

Peter Becker

Coming up in the east on spring evenings is the constellation Bootes, the Herdsman. Its principal stars form what looks more like a kite than someone who herds animals.

If you can find the Big Dipper, Bootes is a cinch, as the top of this “kite” lies immediately off the end star on the Big Dipper’s handle (which, by the way, is known as Alkaid).  At the lower end of the kite figure is Bootes’ most brilliant star and one of the brightest in the sky, lovely orange Arcturus.

Bootes is particularly ancient, and was referred to by Homer in “The Odyssey” almost 3,000 years ago. Numerous cultures have recognized Bootes, in slightly different forms. One story is that the Herdsman is continually keeping watch of the celestial bears that circle the Pole Star - Ursa Major, the Great Bear (containing the Big Dipper) and Ursa Minor, the Little Bear (otherwise known as the Little Dipper).

To help him in herding the bears, he has a pair of hunting dogs in the sky, which make up the small constellation Canes Venatici, basically two stars under the handle of the Big Dipper.

Another legend says that Bootes was the son of Zeus and Callisto. Hera changed Callisto into a bear who was almost killed by Bootes when he was out hunting. Fortunately, she was rescued by Zeus and he took her into the sky where she is now Ursa Major, the Great Bear. Another myth says that he was the son of Demeter, the goddess of agriculture. He was said to have been given a place in the sky for inventing the plow.

The Big Dipper, which constantly circles a point next to the North Star in our northern sky, serves as a very handy pointer. In addition to the front stars of the bowl pointing right at the North Star,  the handle of the Dipper points down to the bright star Arcturus. Continue your swing past Arcturus to another bright, blue-white star, known as Spica. The front stars of the Dipper’s bowl point down to the bright star Regulus, visible about half way up in the south, with the red planet Mars to the left (as seen in 2012).

Arcturus is the fourth brightest star in the night sky, after Sirius, Canopus and Alpha Centauri. Of this elite stellar club, only Sirius and Arcturus may be seen from mid-northern latitudes. It is rated at magnitude -0.04.

Arcturus presently lies 36.7 light years from the sun; it takes that many years for the starlight to reach our eyes. Astronomical distances are always relative (Dr. Albert Einstein would be pleased.)  While we list a star at, say 36.7 light years, it is actually constantly changing. The starry sky seems to our perspective, without sophisticated equipment, quite static. Constellations year after year appear the same in outline; the Big Dipper our great-great-great step granduncle once removed saw appeared the same as you will see it tonight. In actuality, the stars are rushing around the common galactic center. Thousands of years ago, the constellations we know today would be slightly different.

Arcturus has the unique distinction of having the largest proper motion of any bright star, across the sky. The famed astronomer Sir Edmond Halley first detected the motion of this star, in 1718.

In 1933 the light of Arcturus was used to open the World's Fair in Chicago. The star was chosen as it was thought that light from Arcturus had started its journey at about the time of the previous Chicago fair in 1893.

The star is mentioned twice in the Bible , in Job 9:9 and Job 38:32.

The star is an orange-red giant. Stars differ greatly in size, composition, temperature, luminosity and color. Astronomers suspect they go through stages over the eons, as they use up their hydrogen to emit heat and light.

Depending on a host of circumstances, they may eventually end in a supernova explosion or as a small, dim dwarf star.

First-quarter moon is on April 29. Also look for the bright planet Saturn, to the lower right of Arcturus, and right of the bright star Spica.

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Keep looking up!