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The Little Christmas Tree in the December Sky

It’s the holiday season and despite all the hype and hoopla I hope you find much joy and real peace. Since I last visited you in the Pioneer Pree, our Earth, in its orbit around the sun, has reached the point of winter solstice. From now until late June, days will get longer and nights will get shorter.

Unfortunately there really aren’t any constellations or constellation stories that have much to do with Christmas. Taurus the Bull, the constellation I featured last week, doesn't have a red nose like Rudolf the reindeer, but he does have a red eye, the bright star Aldebaran. That's the closest I could come. Most of the names and stories we know for constellations involve early Greek and Roman mythology. Those folks never got into the holiday spirit...not much mistletoe and holly.

There is, however, a miniature but distinct symbol of the holiday season in the eastern sky. You have to dig for it a bit but I think it's more than worth it. It’s called the Christmas Tree Cluster because that’s exactly what it looks like. You’ll need binoculars or a small telescope to see the miniature celestial Tannenbaum, and you’ll need to wait until after 8:30 to see it. That's when it will be high enough above the eastern horizon to get a good look at it.

The Christmas Tree Cluster resides in a very obscure constellation called Monoceros the Unicorn. Forget about trying to see this constellation. It’s just too faint and undefined. The best way to find the Christmas Tree Cluster is to use the bright and famous constellation Orion the Hunter, perched diagonally in the southeastern sky. Orion is the dominant constellation of winter with its three bright stars in a nearly perfect row that make up the belt of the mighty hunter.

On the upper left corner of Orion is Betelgeuse, a bright reddish star that marks the armpit of the hunter. On the upper right corner of Orion is Bellatrix, a star not quite as bright as Betelgeuse. Draw a line from Bellatrix to Betelgeuse and continue that line to the lower left about ten degrees from Betelgeuse. Ten degrees is about the width of your fist at arm’s length. Scan that area with your binoculars or a telescope and you should eventually find the Christmas Tree Cluster. This is a great week to find it because there isn’t much moonlight in the sky.

Once you find the cluster you’ll see that the 20 or so stars in it are arranged in the shape of a Christmas tree, but its bright star is actually at the base of the tree. I truly hope this adds to your holiday spirit! If you look through binoculars the starry little tree will appear on its side pointing to the right. In most telescopes, however, it will appear on its side pointing to the left. That's because the optics in most telescopes give you an inverted view of the heavens.

The Christmas tree shape of the cluster is arguably a pleasant coincidence. The stars just happen to be arranged that way from our view of them from Earth. Like most open clusters this group of young stars formed out of a large nebula of hydrogen gas, much like our sun did over five billion years ago. These clusters of young stars hang out together for several hundred million years until gravity from other surrounding stars break them up.

This Christmas tree is wishing us a Merry Christmas from over 2600 light years away. Just one light year equals almost six trillion miles. The light we see from it tonight left that cluster in 606 B.C. The famous British astronomer William Herschel discovered this cluster in 1783 near Bath, England, and over 200 years later its starry ornaments are still lighting up the tree! Clark Griswold would be so proud!


Diagram: The Christmas Tree Cluster...Click here