Know Your Seven Sisters

This is a great time to view the Seven Sisters open star cluster in the night sky. Look high in the west for a small cloud the size of the full moon. Upon closer examination your eye can catch the individual stars in the cloud and you can start counting. 1, 2, 3, 4, 5, 6... and maybe 7 stars (if you have really good eyesight) in the cluster.

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These are the Seven Sisters, or Pleiades (their family name). They are the children of a Titan named Atlas (the guy that holds up the world) and a sea-nymph named Pleione. The names of the Seven Sisters are: Alcyone, Maia, Taygeta, Celaeno, Merope, Sterope, and Electra. On a clear night you can see Alcyone, Maia, Taygeta, Merope, and Electra along with one or both of their parents.

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Most people with 20/20 vision can only make out 6 stars in the cluster. What happened to the 7th? One legend says that in the ancient Greek days (2500 years ago) they could see all seven. But one star suddenly got dimmer. To explain this phenomenon, the Greeks believed that one of the sisters (Electra in some stories, Merope in others) was sad and covered her face with her hands - thus shielding her beautiful light from the world.

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With any binoculars you can see much more than 7 stars in the cluster. In total the cluster contains over 1,000 members resting about 440 light years away that were all formed from the same nebula. Click on the pictures for close-up views. Try to find them tonight and see how many you can catch.

"Seven Sisters" a painting by Helen Gerro

Tale of Two Clusters in Taurus

Hyades - Do you see the "V?"

Don't worry, Taurus the Bull isn't sick.  He's just got a cluster of stars on his face and another cluster on his back. 

Finding the Bull is pretty easy.  Look for a long, skinny “V” shape above and to the right of Orion. The “V” marks Taurus’ head and long horns as he is about to trample brawny hunter.

If you are still having trouble, find the three stars which mark Orion’s belt and use them as pointer stars. Connect the three dots and continue this line to the right. This line will take you just under a bright, orange-colored star. That is Aldebaran, or the bull’s eye.

How you find the clusters

You'll notice Aldebaran is redder than other stars – “A ruby of dazzling hue.”  And if you look closely you'll see lot of fainter stars all around Aldebaran and the "V" shape.  These are the Hyades star cluster.  All of these stars (except Aldebaran) are about the same distance away and were formed from the same nebula.  They're the closest open cluster in the skies and that's why you can see them with the naked eye.  The ancient Greeks thought they were the five daughters of Atlas who cried all the time over the death of their brother Hyas.  Ever since then, the Hyades have been associated with rainy seasons.   

The name Aldebaran is an Arabic word loosely translated as “The Follower”. What is Aldebaran following? Just continue that line from Orion’s belt past Aldebaran and you will see the most impressive cluster of stars, the Pleiades.



Close up of both clusters

 Maybe you’ve heard of the Pleiades from their alias, the Seven Sisters. At first glance, the stars in the Pleiades look more like a little cloud the size of the full moon. But upon closer examination, you may detect five, six, or seven individual stars in the group. With binoculars you can see approximately 50 stars in the cluster, and with a telescope you can count all 500 of them.  We'll talk more about the Seven Sisters next week, so tune in!

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