With New Moon December 18th, we have dark, starry skies each evening before moonlight begins to paint the dome over our heads. The next clear evening, take in some of the rich star clusters visible, some easily seen with eyes alone, and others easy to find with binoculars. “Dark,” however, is relative. Most of us contend with light pollution to some degree!
Topping the list of star clusters in tonight’s evening sky is the famous Pleiades. Early in the evening in mid-December, look high in the southeast for a glimmering patch of stars. The cluster contains many stars, with six being easily visible to unaided eyes, bunched close together like a little tea cup or dipper.
Otherwise known as M45, the Pleiades are part of the constellation Taurus the Bull. The cluster is full of hot, blue stars and is one of the closest star clusters, 440 light years away. Each light year is approximately 5.8 trillion miles. Light from the Pleiades that you see tonight left the cluster 440 years ago.
Long exposure photographs reveal the bluish clouds (nebulae) around the stars. This expanse of cosmic dust is reflecting the blue light from the cluster’s stars, as the Pleiades moves through the nebula. Looking to the lower left from the Pleiades you will find a bright orange star at the end of a “V” shape string of fainter stars.
This “V” shape is lying on its side from your vantage point (assuming you live in the northern hemisphere), as it rises in the east. This is the Hyades Star Cluster, much wider than the Pleiades, but fainter. The bright orange star is known as Aldebaran, and is not a true member of the star cluster but happens to lie right in line with the cluster stars.
Aldebaran is a giant star, over 44 times as wide as the Sun, and is about 65 light years distant. We actually have a spacecraft on its way to Aldebaran. Pioneer 10, which flew by Jupiter in 1973, is heading towards Aldebaran but it is not expected to pass this star for two million years. Better check the warranty.
The Hyades is the nearest star cluster, only 151 light years away but over twice as far as Aldebaran. Like other star clusters, the stars share a common heritage and, as it were, are siblings to one another. They are moving through the galaxy together. A part of Taurus, Aldebaran is frequently pictured as the bull’s eye and the Hyades as the head; the Pleiades mark a tip of a horn. Moving straight left, leads you to the dim Milky Way Band.
This side of the Milky Way Band, most easily seen in winter, is dimmer and not as wide as the Band in summer evening skies. You will need a very clear, dark night to notice it. Sweeping the region with binoculars will reveal a wonderful assembly of faint stars, packed together and stretching up overhead and down towards the west. As you become familiar with the night sky you will notice that most of the star clusters are within or very close to the Milky Way Band.
Straight left (east) from Aldebaran, with a star chart and binoculars, you can locate the star cluster M35. It will look like a small, fuzzy patch. This is within the Gemini constellation. Just above, and, moving straight left from the Pleiades, look for a very bright yellow star, Capella. This is the brightest star in the constellation Auriga the Chariot Driver.
The Milky Way cuts through here, as if it is the chariot’s highway. Scanning this area with binoculars, you will easily stumble upon at least three “fuzzy patches.” These are, in order from bottom to top, star clusters M37, M36 and M38. These last four are all fabulous sights with a small telescope, showing a tight scattering of stars, like seeing a town at night from an airliner. They are much more distant than the Pleiades or Hyades. M36, for example, is 4,600 light years distant. In the early evening, look straight overhead for the “Double Cluster.”
Appearing as a faint double patch, binoculars will show it easily. This remarkable pair is situated in the Milky Way Band between the M-shaped constellation Cassiopeia and Perseus.
Lastly, most of the stars of the Big Dipper, together with numerous stars scattered across the sky, are believed to be associated, moving together in space and probably once forming a tight star cluster since dispersed. The Sun is believed to be a single star, not part of any cluster.
Keep looking up! —Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at email@example.com. Please mention in what newspaper or web site you read this column.