The Pleiades: Facts about the "Seven Sisters" star cluster

related to Pleiades. Many think that Halloween is descended, in part, from the old pagan festival of Samhain, celebrated by the ancient Celts and Druids of the British Isles. These ancient people may have observed the midnight culmination of Pleiades, or when Pleiades reached its highest point in the sky, at midnight on the day of this festival, which would have been celebrated around the time of Halloween. They believed that this signified the time of the thinnest separation between the world of the living and the world of the dead. 

Mythology

The Pleiades are the seven daughters of the Titan god Atlas and the ocean nymph Pleione. During an ancient war, Atlas rebelled against Zeus, the king of the gods, who sentenced his foe to forever hold up the heavens on his shoulders. The sisters were so sad that Zeus allowed them a place in the sky in order to be close to their father. In other versions of the story, Zeus placed the sisters in the sky to protect them from Orion the hunter, who is represented in a nearby constellation. 

In many different cultures, the Pleiades are associated with young girls being pursued by a young man or men, represented by Orion. Despite this, there is no proof that these cultures, such as the ancient Greeks and Aboriginal Australians, ever encountered each other. Many stories also explain why only six stars are usually visible, even in dark skies, to people with average eyesight. In Greek mythology, one sister left the stars after she fell in love with a mortal. In many Aboriginal Australian cultures, the seventh girl is hiding from the man or men represented by Orion, or has been abducted or killed.

By analyzing the motions of the Pleiades over time using data from the Gaia space telescope, writes astronomer Robert Burnham Jr. suggested that this may also have occurred because Pleione is a shell star, varying substantially in brightness. Therefore, it would have sometimes appeared to be a part of Atlas, while sometimes appearing as a separate star. 

The Pleiades FAQs answered by an expert

We asked Chris Mihos a few frequently asked questions about the Pleiades star cluster.

the sun, so they aren't always in the same spot in the sky. 

The easiest way to find them is to look to the south and find the Orion's belt, and use them as pointers: follow them up and to the right, where you will find the bright red star Aldebaran and then, just a bit further on from there, the Pleiades.

In the southern hemisphere, things are flipped. The time of year doesn't change — it's still the Nov-Mar range — but of course, this is the southern hemisphere's late spring or summer, and the Pleiades will be much lower in the sky from the southern hemisphere. To find them, look to the north to find Orion, then follow his belt stars in a line, this time down and to the left, passing Aldebaran before coming to the Pleiades.