Seven Sisters

As an amateur astronomer I am fascinated by the night sky, but I am equally fascinated by the mythology and legends the ancients attached to the heavens. Most of the bright celestial object have interesting histories surrounding them and at this time of year, one of my favourite surrounds one of the most beautiful winter sky objects, the Pleiades. M45, to give it's official designation, is an open star cluster containing a collection of middle aged stars. It is located in the constellation of Taurus, easily visible at this time in the winter sky. It is one of the nearest star clusters to us and is the cluster most obvious to the naked eye in the night sky. It has been easily visible throughout humanity.

To the ancient Polynesians, all the stars were put there by the God Tane, the god of the forests and the birds. He did so to light the sky up at night, so his father, the sky father, could be better seen in all his finery. However he grew jealous of one particularly bright and beautiful star so he broke it up into several pieces and cast it back into the sky. That star became the Pleiades. The Babylonian's named them “MUL MUL” or "star of stars” and some Greek astronomers thought them to be a distinct constellation in their own right. They are mentioned by Homer in both the Iliad and the Odyssey, hence another name, the “sailing stars”, used by Greek sailors to navigate. The bible mentions them three times and they are also mentioned in both Hindu script and the Koran. The Vikings thought they were a Hen with her chicks and the Lakota tribe of Native Americans had a similar view. To them they were a woman giving birth. Indian astronomers called them the “Six Mothers” but they are best known today as the “Seven Sisters”, after the name given to them by the ancient Greeks to represent the daughters of Atlas and Pleione. The count often depends upon your viewing conditions and your eyesight. Throughout history they have often been used as a test of eyesight. You could not join Napoleons army unless you could see six or seven. The Pleiades is easily visible now in the night sky from here in the UK. It rises early and by midnight is nice and high in the night sky.

Ten of the brightest stars are named but the cluster contains actually over 1000. Interesting the nearest figure given to the actual count comes in at 100. This was the count mentioned once in the bible and also in Ukrainian folklore. Modern science estimates their age at around 75-100 million years old. The cluster's relative motion will eventually lead it moving through our sky, eventually passing below the feet of Orion. Like most open clusters, the Pleiades will not stay gravitationally bound forever, it cannot. Some component stars will be ejected after close encounters with others and some will be thrown out by gravitational tides. Calculations suggest that the cluster will take about 250 million years to disperse, so we still have plenty of time to enjoy it, and maybe make a few more myths.