M45 is an object that has been known since the earliest times. Most commonly known as the Pleiades, it is an open cluster of about 500 young stars located within the constellation of Taurus. This cluster has also been named the Seven Sisters, after its seven brightest stars. These stars can easily be seen with the naked eye. The Pleiades are believed to be very young - only 100 million years old. They are located only 380 light years from Earth.