Discovered by William Herschel on November 16, 1784.
NGC 2158 is a beautiful dense open cluster of stars situated only about one quarter of a degree to the southwest, but much more distant, to its better known cousin, M35. NGC 2158 is very compact for an open cluster and was considered as a globular by Rosino (1954). The current classification maintained by most astronomers is that of a very old Galactic Open Cluster. The age of the cluster is estimated to be approximately 1.05 billion years. The cluster consists primarily of old stars giving it a decidedly yellow color. NGC 2158 lies at an estimated distance of 16,000 light years from the earth.