14 DAY TRIAL // In spite of cataloging all deep-sky objects as things that could be mistaken for comets, famed astronomer Charles Messier somehow managed to miss adding the Double Cluster on his list. As such, the structure now doesn't have an “M” number, unlike most of its neighbors. While Messier ignored the structure, there is no reason why astronomers today should do the same.
It can be resolved in the night skies using either a telescope or a pair of binoculars. The structure looks like two large spheres of light through a pair of binoculars, but changes its appearance to two clusters filled with hundreds of stars, as soon as a good telescope is pointed at them.
Both clusters in the formation are located approximately 7,000 light-years away from our Sun, and can be identified by starting from the two stars at the middle of the “W”-shaped structure that is Cassiopeia. The 2nd magnitude constellation points directly at the Double Cluster, which is located inside Perseus. Both components of the Cluster are ten million years old, but, in spite of their similarities, they differ considerably in appearance from each other.
They vary significantly in stellar concentration and density, although they share the same history and evolutionary path. The main reason why the structure appears colorful is the fact that the mass blue-white young stars that make it up is dotted with older, yellow stars. The contrast between the two makes both Double Cluster components appear in various hues to Earth-based observers. The common names for the two structures inside are the open clusters NGC 884 and NGC 869. Both of them are approaching our planet at a speed of 21 to 22 kilometers per second.
One of the celestial bodies that can be identified next to the Double Cluster is the Alpha Perseii Cluster, which is very close to the Sun, at a distance of only 600 light-years away. Oddly enough, in spite of being one of the nearest and largest clusters to our planet, it has been studied only marginally by astronomers. The main reason for this is the fact that it is simply too large to view in a telescope, and overflows the viewing field of a normal binocular as well. Therefore, it is one of those structures that are best viewed with a small-magnification binocular, or with the naked eye, Space reports.