Hyades (star cluster)

The Hyades are an open star cluster located in the constellation Taurus. The closest obvious star cluster to Earth (the Ursa Major cluster is closer, many astronomers consider the Sun to be inside it, but it is more spread out in the sky as a consequence), it is centered some 151 light years away. The brightest star in this direction is Aldebaran, but it is not a member of the cluster, being located at just over 40% of the distance. Not counting Aldebaran, approximately 300 stars are known or suspected to be members of the cluster; most are not visible to the naked eye.

The Hyades open star cluster (within the large rectangle but excluding the brightest star Aldebaran) and the Pleiades (small rectangle)

The stars of the Hyades are associated with one another in the sense that they are all moving in approximately the same direction and at the same speed through the galaxy. Plotting their movements backwards eventually brings them all to a more or less a single point about 600-800 million years ago, a fact explained by the theory that they all formed in the same stellar nursery . The stars of the Praesepe star cluster may also be related.

This common motion was only demonstrated in 1908 by astronomer Lewis Boss, but the Hyades have been known since antiquity. The name itself dates back at least as far as 1000 BC, when it is mentioned in various Greek sources.