The Seven Sisters, also called the Pleiades or M45, is an open star cluster located about 400 light years away towards the constellation Taurus. It is about 13 light years across and is one of the brightest and closest star clusters to us.
The cluster contains over 3000 stars, most of which are considered middle aged. Surrounding the brighter stars are reflection nebulae, gas and dust reflecting the light from the stars. Also buried in the cluster are faint, low mass brown dwarf stars.
The undulating cliffs known as the Seven Sisters rival even the White Cliffs of Dover for ivory clarity but the constant crashing of the ocean waves at their base is causing them to fall piece-by-piece back into the ocean.
Startlingly picturesque, the cliffs are known as the “Seven Sisters” due to the seven distinct hilltops that comprise the silhouette of the cliffs. The bright white color of the stone is thanks to the abundance of chalk that makes up most of the cliff face. The features were created in prehistoric times when the land was submerged and seawater pushed the softer chalk to the surface and as the waters lowered, exposed the cliffs. Now as the sea pounds the base of the cliffs each day, erosion is slowly taking the chalk back as large chunks of the cliffs wall back into the water.
Luckily for the Seven Sisters Cliffs, it this very process of erosion that has allowed them to retain their white pallor since similar cliff faces around the world have received increased protection which halts the erosion, they have begun to accumulate vegetation that is slowly mottling their color. This has led to the Seven Sisters being used in a number of films such as Robin Hood: Prince of Thieves and Atonement.
The Pleiades, also known as the Seven Sisters, is a neighboring star cluster located 400 ly away in the constellation Taurus. It can be easily seen with the naked eye and has an apparent magnitude of 1.6. The open cluster consists of approx. 3,000 luminous, blue stars.