M 45 is commonly referred to as the Pleiades, also the Seven Sisters. In Japanese culture, it is known to as Subaru ("coming together"). It lies in the constellation of Taurus. At a distance of 425 light years, it is one of the closest star clusters to us. It is composed of type B stars that are between 75 and 150 million years old, approximately 1/50 the age of our sun.

It was believed that the nebulae around the stars were remants of the star cluster formation. We now know that this nebulosity is unrelated dust through which the stars' light passes.