Object Analysis

The Double Cluster (NGC 869 and NGC 884) consists of two open clusters visible to the naked eye in the constellation Perseus. Both clusters are located in the Perseus Arm of the Milky Way galaxy at distances of 7,500 and 7,600 light-years, respectively. They are physically close to one another, separated by only a few hundred light-years.

The clusters are very young—only about 12.8 million years old. This youth is evident in the presence of more than 300 blue-white supergiant stars in each cluster. These massive stars burn through their fuel quickly and are destined to explode as supernovae.

Unusually for open clusters, the Double Cluster is blueshifted, meaning it is approaching Earth at a speed of roughly 22 km/s. In small telescopes, the clusters appear as a spectacular scattering of diamond dust, often described as one of the finest visual objects in the northern sky.