The Pleiades also known as the Seven Sisters and Messier 45, is an asterism of an open star cluster containing middle-aged, hot B-type stars in the northwest of the constellation Taurus. At a distance of about 444 light-years, it is among the nearest star clusters to Earth and the nearest Messier object to Earth, being the most obvious star cluster to the naked eye in the night sky. It is also observed to house the reflection nebula NGC 1432, an HII region.