Looking Up: 'V' Is For Hyades

Feb 26, 2018

Pleiades to Hyades: This cosmic vista stretches almost 20 degrees across Taurus. It begins at the Pleiades and ends at the Hyades, two of the best known star clusters in planet Earth's sky. At left, the lovely Pleiades star cluster is about 400 light-years away. At right, the V-shaped Hyades cluster looks more spread out compared to the compact Pleiades and lies much closer, 150 light-years distant.
Credit Image Credit & Copyright: Rogelio Bernal Andreo / nasa.gov

There are two 'sister' star clusters in the constellation Taurus the Bull. This week on Looking Up Bruce Bookout introduces us to the five daughters of Atlas... the Hyades.

Over the last few years we have discussed the beautiful winter asterism known as the Pleiades. These fair maidens of the night are an easily found object high above in the constellation Taurus the Bull.  What most observers overlook are the other sisters that form a ‘V’ shape that marks the head of the  celestial bull.

The Hyades is an open cluster much like the Pleiades, but one third the distance to us; a mere 150 light years away.  While the bright star Aldebaran appears to be the brightest, “the bull’s eye”, it is unrelated to the cluster, just happening to lie along the same line of sight.  While the legend only tells of five sisters in the cluster, observations show over 200 associated stars.

In legend, the Hyades were the five daughters of Atlas, half-sisters to the Pleiades, and the sisters of Hyas, the hunter. One day, Hyas was killed by a lion and the Hyades were so overcome by grief that they committed suicide. The god Zeus transformed the sisters into a star cluster and placed them in the constellation Taurus. Since the Hyades rise in the sky during the Mediterranean rainy season, the Greeks believed their appearance to be harbingers of spring showers, the rain representing their tears of grief for their lost brother Hyas. I hope that wasn’t too a terra-bull of a story. 

Recognized since antiquity and depicted on the shield of Achilles according to Homer, stars of the Hyades cluster form the head of the constellation Taurus the Bull. Their general V-shape is anchored by Aldebaran, the eye of the Bull and by far the constellation's brightest star. Yellowish in appearance, red giant Aldebaran is not a Hyades cluster member, though.
Credit Image Credit & Copyright: Jerry Lodriguss (Catching the Light) / nasa.gov

If you’d like to take a closer look at the Hyades, or any of the other wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties!