The “Raining Stars”
Many constellations host tiny open star clusters. But a only a few constellations find themselves completely dominated by the bright stars of a single nearby open cluster.
Coma Berenices is one example. So is the Ursa Major Major Moving Group, a star cluster which includes the innermost five stars of the Big Dipper.
*** Highly Recommended ***
A concise guide to observing nebula, galaxies, and star clusters. Secrets of the Deep Sky introduces you to the universe beyond our solar system. Includes tips on equipment selection and observing techniques, along with a tour of dozens of lovely sights in the north and south hemispheres. Click here to learn more…
* * * * * * * * * *
But the best-known example is the constellation Taurus the Bull, which gets its famed V-shaped head from a lovely open cluster of blue and orange stars called the Hyades. Often overshadowed by the smaller and more famous Pleiades, the Hyades are visible high in the northern sky this time of year. They’re visible from the southern hemisphere, too, perhaps 20 degrees above the northern horizon just after sunset in South Africa, Australia, and New Zealand.
The Hyades have been known since antiquity. The cluster’s name comes from the Greek legend of the seven Hyads, the daughters of the titan Atlas and Aethra. Atlas was busy because he had seven more daughters by another wife, Pleione. These daughters were called the Pleiades. So by legend, the Pleiades and the Hyades are half-sisters. Unlike the Pleiades star cluster, the stars of the Hyades are not named after the sisters. And the Hyades contains some 20 stars visible to the naked eye; the Pleiades have just six.
The Romans called the Hyades Sidus Hyantis, the “Raining Stars” because legend tells the Hyads rained tears on Earth after the death of their brother Hyas. The appearance of these stars also coincided with the rainy season around the Mediterranean.
(Perhaps those of us at northern latitudes should call the Hyades the “Snowing Stars”).
The center of mass of the Hyades is just 151 light years away. So save for the Ursa Major moving group mentioned above, the Hyades ranks as the closet star cluster to Earth. Astronomers have carefully measured the apparent motion of the Hyades across the sky and determined it moves away from Earth and toward a point just east of the bright star Betelguese. Fifty million years from now, the cluster will appear dim and small, just 0.5 degrees across.
The presence of many orange-giant stars suggests the Hyades have been around for some 700 million years. That’s old for an open cluster. It’s likely no coincidence that the Hyades are about the same age as the Praesepe star cluster (M44) in Cancer. The two clusters have a common motion through space, and likely formed together out of the same massive cloud of gas and dust.
The Hyades appears to be dominated by the bright orange star Aldebaran, which appears as the “eye” of the bull and the brightest star in the constellation Taurus. But Aldebaran is not associated with the Hyades. It’s much closer… just 65 light years away.
The Hyades is the V-shaped group of stars halfway between the Pleiades and the bright star Betelguese in Orion. You need no telescope to observe the them.The cluster is spread out over a patch of sky as large as your fist extended at arms length, and 11 stars shine at magnitude 4.5 or brighter. A modest pair of binoculars reveals dozens more stars, and the whole cluster is quite dazzling. Once you locate the group in the sky, the map below, taken from Stargazing for Beginners, will help you find your way around.
A map of the Hyades star cluster, adapted from Stargazing for Beginners: A Binocular Tour of the Night Sky
In the next (much shorter) article, we’ll show you 3 pairs of stars in the Hyades that provide an excellent challenge for visual observers and are a great way to test your observing skill and ability.
