NGC 2129

NGC 2129 is an open cluster in the constellation Gemini. It has an angular distance of 2.5 arcminutes and is approximately 2.2 ± 0.2 kpc from the Sun inside the Local spiral arm. At that distance, the angular size of the cluster corresponds to a diameter of about 10.4 light years. NGC 2129 is a very young cluster whose age has been estimated at 10 million years. It was discovered by William Herschel on November 16, 1784
The group is dominated by two close B-Type stars, HD 250289 and HD 250290. With the two stars sharing the same proper motion and radial velocity it is likely that the two constitute a binary system.
On 21 December 2010 it was occulted by the Moon during a Total Lunar Eclipse over Japan, the North Pacific and North America. This will happen again during the December 2029 lunar eclipse over South America, the Atlantic Ocean and Africa, and again on 21 December 2094 over New Guinea, Northern Australia and the Pacific Ocean.