Jimmy Westlake: How Leo lost his tail
April 5, 2011
Steamboat Springs — There are star clusters visible to the unaided eye, but there is only one star cluster that forms a constellation all by itself. You can see it high in the eastern sky on spring evenings as a smattering of several dozen faint stars, not far from the familiar outline of the Big Dipper. This is the constellation we call Coma Berenices, or Queen Berenice's Hair, and it is one of only a few constellations associated with a real person rather than a mythological one.
On ancient star charts, today's Coma Berenices constellation is shown as representing the tuft of hair on the end of the tail of nearby Leo the Lion. But in 1602, the lion's tail was cut off and made into this new constellation by famed Danish astronomer Tycho Brahe. Legend tells us that the constellation represents the hair of Egyptian Queen Berenice II, who lived around 245 B.C. Apparently, she had made a vow to cut off her beautiful hair and place it in Aphrodite's temple if the goddess would return her husband, King Ptolemy III, safely from battle. The king did return victorious from battle and Berenice clipped off her beautiful locks and placed them in Aphrodite's temple as an offering. But the tresses mysteriously disappeared overnight. The king suspected that the court astronomer was responsible. When questioned, the quick-thinking astronomer pointed skyward to an unnamed star cluster and explained that Aphrodite was so touched by the love offering that she had placed the Queen's hair in the sky for all to see for eternity. It's a good thing the king was unfamiliar with the starry sky or he might have recognized the star cluster as Leo's tail. As it turned out, the king fell for this story and spared the astronomer's life.
Far beyond the Coma Berenices star cluster, modern astronomers have discovered another kind of cluster, a cluster of more than 3,000 galaxies, lying at a distance of 280 million light years. The Coma cluster of galaxies is one of the largest such clusters known to astronomers.
What we really have, then, is a cluster of galaxies hiding within a cluster of stars, disguised as Queen Berenice's beautiful hair. Look for the heavenly locks at about 9 p.m. along the leading or western edge of the Spring Diamond asterism, composed of the four bright stars Arcturus, Spica, Denebola and Cor Caroli.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer. Check out Jimmy's website at http://www.jwestlake.com.