Collinder 189

Collinder 189 is the Beehive Cluster, also known as Praesepe, Messier 44, NGC 2632 and Melotte 88, a large, bright open star cluster in the constellation Cancer. It is one of the nearest open clusters, about 580 to 610 light-years away. It has a bright core about 7 parsecs (23 light-years) across, and 1.5° as a whole, so it fits in the field of binoculars. It contains around 1,000 stars about two-thirds of them red dwarfs. It stands out as one of the oldest clusters known to humanity: ancient astronomers saw it as a “nebulous mass”, Ptolemy described it as one in the breast of Cancer, and Galileo resolved it into about 40 stars with his telescope. Its age (about 600 to 700 million years) and motion through space match those of the Hyades, so the two may share an origin. In 2012 two planets were found orbiting separate stars in the cluster, and the K2 mission found more. The cluster also contains red giants, white dwarfs, an eclipsing binary (TX Cancri) and several Delta Scuti variables.