My date with the Seven Sisters

The Pleiades is an open star cluster in the constellation Taurus and, at this time of the year, makes its entrance in the north eastern skies of the northern hemisphere round about midnight. Popularly called the Seven Sisters, it is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky.

These stars are so clearly seen in the night sky that even those who do not dabble in astronomy can easily spot them - at least 6 or 7 bright stars, gathered in a region only a bit larger than 1 degree, are clearly seen with the naked eye. See the little cluster of stars near the bottom right hand side of the picture below?

The Pleiades have been used for testing eyesight from antiquity onward. In good observing conditions, an observer with average sight can see 6 stars. What about people with excellent eyesight? Maestlin, the teacher of the astronomer Kepler, saw 14 stars; he had drawn 11 stars on charts of the Pleiades before the telescope was invented! The well-known English observer Denning also saw 14 stars in the cluster. Madame Airy (the wife of a well-known nineteenth-century English Astronomer Royal) could see 12, while the English amateur astronomer William Dawes, who was in his time known to have extraordinary eyesight, saw 13 stars in the cluster. How many can you make out in my picture below?

If the Pleiades seem charming with the naked eye, they are truly breathtaking when viewed through a small low-powered telescope  or binoculars! The six stars are suddenly joined by numerous fainter ones, making the field of the cluster literally overflowing with stars, as you can see in my image below. Investigations of the cluster have shown that it may actually contain approximately 500 stars.

If I'd always felt slightly deprived because of the relatively low magnification of my telescope set-up, when observing the Pleiades low magnification becomes an advantage. The large field of view of a small refractor offers a panoramic view of this splendid group. With larger amateur telescopes or at high magnifications, we somewhat lose the magnificent feel of this cluster. Below is an image of the centre of the Pleiades taken at high magnifications.

In Greek mythology, the Pleiades were the seven daughters of the titan Atlas and the sea-nymph Pleione - Maia (the eldest), Electra, Taygete, Alcyone, Celaeno, Asterope and Merope (the youngest). However, because most people can only see six of the Seven Sisters, this has inspired legends of the “Lost Pleiad.” The most commonly told is that Electra - she’s shocked to see her home city Troy burning and hides her face. Another story says Merope wasn’t made as bright as the others because she married a mortal - the other sisters married immortals. Yet another story says she couldn’t fit in with the other sisters anymore and left for Hades. In another story, a thunderbolt hit Celaeno and she disappeared.

Intriguingly, other cultures such as the Aborigines of Australia and Iroquois of North America had similar legends of a missing seventh star. Some modern astronomers think that means there may actually have been seven stars easily visible a long time ago. The Greeks, the Iroquois, and the Aborigines may have told stories appropriate for their own cultures to explain why one vanished. If that’s true, one of the many Pleiades we see in a magnified view could have been the one that faded from naked eye visibility.

All photographs on this page  © Sabri Zain 2012.