The Mystery Of The Seventh Sisters
If you go out on the next clear night and gaze up in the eastern sky, you will see a small but conspicuous cluster of stars. They are close enough together that if you hold out your fist at arms length, you will cover them up. This group of stars is the Pleiades, known to many of us as the seven sisters.
Drawings and stories of the Pleiades go back for over a thousand years. It seems every culture throughout history has seen this group of stars as significant. They are not a constellation by themselves, but are part of the constellation, Taurus the bull.
There is a mystery to this group of stars, however. If you look at them and count them, you will count only six stars. Binoculars or a telescope will show you many more, but there are only six stars easily visible. Why, then, do we hear them called the seven sisters? It seems that ancient cultures either saw seven stars or were convinced there ought to be seven and so invented stories to explain it.
One Greek myth said that the group of stars were seven sisters, however, one got struck by lightning and was no longer visible. Other Greeks said there were originally seven sisters, but one married a mortal and was then so ashamed, she hid her face. The Roman poet Hyginus said that the seventh sister was changed into a comet.
The North American Indians also seemed to wish for seven stars. The Iroquois of New York say that the stars are seven brothers, but that one fell back to Earth. The Wyandot Indians of Ontario explain that there are seven sisters, but one of them married a mortal. The seventh sister and her mortal husband must sit in the back of the basket in which they all ride, and so are not easily visible.
Rumanians saw seven stars, a hen and six chicks. But the Barasana Indians of Columbia speak of eight stars in the group. Apparently it's a personal thing!
So what is the answer to the question of why so many peoples have seen and made up stories about seven stars, many of which explain why one star became dim? Could one star have been bright and then dimmed? Astronomers are not sure, but there is at least one thing that the astronomers and most of the myths have in common; the stars of this group are related to one another.
Astronomers do know quite a bit about the Pleiades, however many they can see, and telescopes show about 300. The Pleiades is an area where young stars are forming, a stellar nursery if you please. All of the stars in the Pleiades are young stars in astronomical terms, only about 100 million years old. By comparison, our Sun and solar system have been around for about 50 times longer, and our Sun is only approaching middle age! The Pleiades will be around for a very long time.
Several explanations have been offered to explain that seventh star. Perhaps one star has gone dim, or perhaps interstellar dust swirling around the group and the dust has thickened around one star and has obscured it from view. Long exposure photos support this idea, but a dust cloud would take more than a few thousand years to change the brightness of a star. Also, a few thousand years would also not be enough time for such young stars to dim for any other reason that we know of.
Another possible explanation is that the seventh star may be an erratic variable. Variable stars are stars that vary in brightness over a period of time. They cycle between peaks, going from brightest to dimmest. Only a few naked eye stars have a large enough variance to actually be seen, however. But there are some variables that have an erratic period, and the variance is much greater in both time and magnitude.
These explanations are weak, but whatever the answer, and however many Pleiades you see, they are a pretty sight. If you go out to look for the Pleiades, they are very easy to find, and they will be with us all winter. See how many you can count.
Copyright © 1995 - 2008
Kathy Miles, Author,
Go to www.dmatarazzo.org, then to Deep Sky. Find the Zuni image of Pleiades and place it in your article. Wrap around to the left.