Doorstep Astronomy: The Moon and a Star Cluster
The moon pays a visit tonight to the Pleiades star cluster, plus the bright stars Capella and Aldebaran.
Credit: Starry Night® Software

Take a look to the east around 11 o?clock your local time Wednesday night, and you?ll see a pretty sight. The rising gibbous moon will be low in the eastern sky. Look closely just above it and you?ll see a small cluster of stars, known as the Pleiades.

It is a great opportunity to use the moon as a marker to find a gorgeous sky scene you might not otherwise notice.

To the naked eye, the Pleiades appears as six or seven bright stars in a slightly hazy looking group. If you look more closely, with binoculars, you?ll see the reason for this ?haze?: a number of fainter stars, too faint to be seen as individuals.

The Pleiades is the brightest and best known star cluster in the sky, located 410 light-years from the sun. The six or seven brightest stars, visible to the naked eye, form a miniature ?dipper.? In ancient times, these were seen as seven sisters, and figure largely in many myths around the world. In Japanese they are known as Subaru, and form the logo of a well known automobile manufacturer. In modern times, they are sometimes called ?the Shopping Cart,? after the vehicle we see in every supermarket.

These stars share a common and fairly recent origin. The gaseous nebula from which they formed has now dissipated. On very dark nights, wisps of nebulosity are visible around some of the stars, but this is light reflected from a nebula they just happen to be passing through, not the nebula which gave birth to them.

Just below the Pleiades is another open cluster, the Hyades. This cluster is only 150 light-years away, so the stars appear more widely spread across the sky. Although the bright red giant star Aldebaran looks like a member of this cluster, it is in fact less than half as far away as the Hyades proper.

The Pleiades and the Hyades are both part of the constellation Taurus, the Bull. The V-shape of the Hyades forms the muzzle of the bull, with Aldebaran as its glaring red eye. The Pleiades ride on the shoulder of the bull, kept safe from the unwanted attention of Orion the Hunter, whose bow is just peeking above the horizon below Aldebaran.

If you look off to the left of the moon, you will see the bright star Capella shining in solitary splendor. It forms one corner of the pentagonal constellation Auriga, the Charioteer. Along with Aldebaran it is the first star of winter, soon to be joined by the other bright winter stars of Orion, Gemini, and the two dogs, Canis Major and Minor.

This article was provided to by Starry Night Education, the leader in space science curriculum solutions.