Celestial News: Mato Tipila and the Seven Sisters
November 1, 2018
Rising in the eastern sky as the last colorful rays of sunlight fade from the mountaintops in early November is the magnificent constellation of Taurus, the Bull. Taurus boasts the flashy orange giant star Aldebaran, the 13th brightest star in our sky, as well as two sparkling star clusters visible to the unaided eye.
The familiar V-shaped asterism of Taurus' face is like no other group of stars visible from Earth. Collectively known as the Hyades, the stars that outline Taurus' face are all members of a single star cluster, born together as one family — with one notable exception.
he brightest star in this flying wedge, as I used to call it as a kid, is Aldebaran, an orange giant star marking the glaring eyeball of the heavenly bull. Aldebaran is a foreground star, only half as far away as the Hyades and conveniently superimposed atop the left fork of the V.
The Hyades boasts at least a dozen stars visible to the unaided eye on a dark night, but hundreds of fainter cluster members lurk just below the threshold of visibility. This is where a pair of binoculars comes in handy.
The Hyades cluster, 153 light years away, has the distinction of being the closest star cluster to our solar system. Astronomers hone their distance measuring skills on the nearby Hyades cluster to better measure the distances to other stellar clusters much further away.
The brightest Hyades stars outlining the V of the bull's face are all orange giant stars, born about 625 million years ago. These stars have already fused up their hydrogen fuel and are entering their final stage of life, cooling and swelling at the same time into orange behemoths that would dwarf our sun. Hyades stars more massive than these few have already run their course and blown themselves to smithereens as supernovae.
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Leading the Hyades westward across the sky is Taurus' second star cluster, the Pleiades, marking the bull's shoulder. Popularly known as the Seven Sisters and often mistaken for the Little Dipper, the Pleiades star cluster is one of the most beautiful naked eye sights in the entire sky.
Most folks can see five or six stars with ease — the seventh star is more of a challenge. The Pleiades cluster is nearly twice as far from us as the Hyades and, consequently, appears much smaller in size. At an age of about 100 million years, the stars of the Pleiades are also much younger and bluer than the stars of the Hyades cluster.
Both the Hyades and Pleiades star clusters are steeped in ancient legend and lore and have been pondered by curious eyes since antiquity. The following is a sampling of the star lore surrounding these two clusters.
In Greek mythology, Hyas was the son of a Titan named Atlas. His seven half-sisters were the Hyades. Hyas grew into a skilled archer and hunter, but one day wound up being killed by his prey — a wild boar.
His sisters were so grief stricken that they wept themselves to death. Zeus, the king of the Greek gods, immortalized the sisters by placing them in the heavens as the Hyades star cluster.
During the rainy months of April and May, the Hyades are too close to the sun in our sky to be seen. The Greeks considered the springtime rains as the never-ending tears of the Hyades, weeping for their fallen brother.
The Pleiades were also the seven half-sisters of the Hyades, by a different mother. After Atlas and the Titans were defeated by Zeus and the Olympians in the great war for control of the universe, Atlas's punishment was to toil for eternity, holding the sky on his shoulders. Unable to look after his daughters, Atlas had to watch helplessly as the brute Orion relentlessly pursued the seven beautiful Pleiades.
Zeus took pity on them and first changed them into doves so that they might escape Orion's advances before finally changing them into the seven twinkling stars of the Pleiades star cluster, just out of Orion's reach. He placed them in the heavens beside their grieving half-sisters, the Hyades.
While visiting Devil's Tower National Monument for the first time this summer, I learned of another legend about the Pleiades, this one from the Kiowa people.
Seven little Kiowa girls were out playing in the forest picking flowers one day when they were spotted by a giant grizzly bear. They climbed to the top of a large rock and prayed to the Great Sprit to save them from the charging bear.
Like magic, the large rock began to grow out of the ground and carried the seven girls high above the pine forest. The growling bear tried to climb the steep tower of rock, gouging out long vertical grooves with his claws on all sides before giving up.
The Great Sprit turned the bear into the stars of Big Dipper and the seven Kiowa girls into the glittering stars of the Pleiades cluster. The grooved tower of rock that we call Devil's Tower was known to the Kiowa as Mato Tipila, the Bear's Lodge.
Look for the Pleiades and Hyades star clusters about midway up in the eastern sky around 9 p.m. this month.
Jimmy Westlake retired from full-time teaching at Colorado Mountain College's Steamboat Springs campus in 2017, after 19 years as a professor of physical sciences. Celestial News appears monthly in Steamboat Pilot & Today. Check out Westlake’s astrophotography website at jwestlake.com.