The Beautiful Hyades and Pleiades
Taurus, the Bull, is home to two of the most famous and beautiful open star clusters – the Hyades and the Pleiades.
The Hyades, whose stars make up the distinctive V-shape of Taurus’ face is a brilliant collection of young, mostly blue-white stars that are lovely to the naked eye and just gorgeous in a pair of binoculars.
The Pleiades sit on the bull’s shoulder and is arguably the most striking naked eye cluster. and they are absolutely dazzling in binoculars. Visible from virtually every part of the globe both clusters were objects of wonder, myth and legend in the clear and unpolluted night skies of antiquity, and spawned beautiful myths in cultures across the world.
Finding the Hyades and Pleiades
Simply follow Orion’s three belt stars to the northwest to find the V-shaped Hyades star cluster and the bright star Aldebaran. Once you have found the Hyades, the small and brilliant Pleiades is unmistakable. (And if you follow Orion’s Belt in the other direction, you’ll find the bright blue-white star Sirius, the brightest star in the sky.)
The Hyades
The Hyades is our nearest open star cluster, a mere 151 light years distance from Earth. The cluster contains up to a thousand stars within a region some 20 light years across. Because the cluster is so close to us its stars appear very spread out. So much so that it can be difficult to perceive them as a distinct group against the sky. The cluster’s naked eye stars, being young, hot blue-white stars are much brighter than our sun – in fact, if the sun were placed in the cluster it would be too faint to view.
The brightest star in the V-pattern of Taurus’s head is brilliant red Aldebaran. It represents the glaring Bull’s eye taking a bead on Orion, the Hunter, before beginning to charge. However, Aldebaran is an interloper; it is not a member of the Hyades as it lies way closer to us, only 65 light years away. (The name Aldebaran comes from an Arabic word for “follower”. It’s thought to be a reference to this star’s forever chasing the Pleiades across the heavens.)
The legend of the Hyades
The cluster’s name comes from the Greek legend of the seven Hyads, the daughters of the Titan Atlas (who was compelled by the gods to support the heavens on his shoulders) and his wife, Aethra. Atlas, a busy man, had seven more daughters by another wife, Pleione. These daughters were called the Pleiades. So by legend, the Pleiades and the Hyades are half-sisters. The Romans called the Hyades the “Raining Stars” because legend tells the Hyads rained tears on Earth after the death of their brother Hyas. The appearance of these stars also coincided with the rainy season around the Mediterranean.
Observing the Hyades
Around twenty of the Hyades’ stars are visible to the naked eye and its glittering V-shape is surely one of the loveliest sights in the sky. And it is gorgeous in binoculars! Dozens of stars are revealed, among them a stunning double star, theta Tauri. It’s easy to pick out naked eye – it’s the bright star not quite halfway between Aldebaran and the point of the V – and in binoculars they are a brilliantly bright pair. (A double star is two stars that are gravitationally bound to each other. They are orbiting a common centre of gravity and will be together until the end!)
The Pleaides
The Pleiades – or Seven Sisters – is the most famous of all star clusters. The cluster is only about 100 million years old (which is young in astronomical terms); it contains some 3,000 stars and lies about 444 light-years from Earth. The cluster’s central region spans about 12 light-years, with the diameter of the Pleiades as a whole estimated at around 35 light-years. Like a school of stellar fish, its members move together as a gravitationally-bound swarm through space.
The beautiful blue reflection nebula that one sees in photos of the Pleiades is not remnants of its star-birth cloud, which would have burned away a long time, but a random cloud of interstellar gas and dust that the cluster is passing through at the moment. (You won’t see the nebula in binoculars.)
Humans have been looking at this glorious cluster for a long time – ancient humans painted the Pleiades on the walls of the Lascaux caves in southwestern France around 16,000 years ago. It is amazing to the see the Pleiades (represented as a group of black stars) above the bull’s shoulder, and the alignment of stars of Orion’s Belt in front of the bull’s snout. One wonders what myths and legends they spun around the Pleiades? And what they called the strikingly beautiful little cluster.
The legend of the Pleiades
According to Greek myth, after a chance meeting with the hunter Orion, the Pleiades became the object of his pursuit. Enamoured with the young women he pursued them over the face of the Earth. Their father, Atlas, holding the heavens on his shoulder, was unable to protect his daughters so he asked Zeus to intervene. Zeus did so by transforming the sisters into a group of beautiful stars.
The names of the Pleiades
The nine brightest stars of the Pleiades are named after the seven sisters: Sterope, Merope, Electra, Maia, Taygeta, Celaeno and Alcyone, and Atlas and their mother, Pleione are included. It is tremendous to look at these fabulous stars and know them by name.
Observing the Pleiades
Naked eye, the Pleiades is a dazzling and entirely mesmerizing object. The cluster is the most enchanting shape. Most observers report only seeing six stars, causing the dimmest of the sisters, Pleione, to be nicknamed ‘the lost Pleiad’ (which led to some lovely mythology and poetry). Other observers have recorded seeing a couple more and some very sharp-eyed observers quite a few more!
There’s an adage in astronomy that applies well here: the more you look, the more you’ll see. Put simply, the longer you study this cluster the more likely you are to see more stars (but you need to have spent enough time in the dark to allow your eyes to become well dark-adapted).
The Pleiades is possibly the most stunning binocular object, one which very few stargazers fail to return to each summer when they are gracing our southern skies. Turning your binoculars to them is like opening a box of diamonds. The nine brightest stars glitter like a handful of icy blue diamonds scattered on black velvet, with more of their smaller blue-white members sprinkled around them like diamond chips. Counting fifteen stars or so is easy – and under pristine dark up to thirty are visible for the sharp-eyed observer. The Pleiades is one of the few objects where the view through binoculars is as good as the photos you find in books.
Copyright © Susan Young 2023