The Beehive Cluster – Praesepe – M44

Open Cluster

The Beehive cluster is located in the constellation of Cancer the Crab. It is quite large and bright and on dark, clear, moonless night away from bright city lights you can just make it out with the naked eye. The secret is knowing where to look. It is a very easy target in a pair of Binoculars.

First Find the constellation of Cancer the Crab. If you have been coming to the star talks at the planetarium this winter you should be familiar with the winter circle that is made of of six of the brightest stars in the winter sky. We can use 2 of those stars to help locate Cancer that does not have any real bright stars in it. Find the bright star Procyon that is part of Canis Minor (the small dog). Slowly scan east (to the right) you’ll see a group of faint stars shaped like the letter ‘Y’ like the chart below shows. You can also find that area of the sky if you scan south from The bright star Pollux in the constellation of Gemini. Don’t despair if you can’t see it right away. A bright moon or some wispy clouds can make it hard too see.

This chart is for the night of March 21^st at 8:00 PM. Overhead is a the top. You are facing Southeast.

You may be able to see a slight glow near the center of the ‘Y’. That’s it! You found it. If not, then its time to break out the binoculars and look at the star in the center of the ‘Y’. Scan around and you stumble across a large grouping of bright stars.

I use 10 x 50 binoculars. Those give me a Field of View of about (4.5 degrees). If you look at the star charts you will see a red circle. This is the area of the sky I am seeing through my binoculars when I am looking through them. The 10x means my binoculars magnify 10 times. The 50 stands for 50 millimeter, the diameter of the main lenses of my binoculars. You may have 7 x 35 binoculars. Can you decode what that means?

Just like telescopes, the bigger the lens, the more fainter the things you can see. Tim, an astronomer at the planetarium often brings his 20 x 80 binoculars to sky watching events. Those are huge.

The Beehive star cluster goes by many other names. Praesepe means manger because some thought that the stars looked like a stable full of animals. Charles Messier, a famous comet hunter, thought this glow in the sky was a comet but was wrong. So he made a list of things in the sky that looked like comets but weren’t so he wouldn’t make the same mistake twice. The Beehive was the 44^th entry on his famous list of 110 objects and is also known as M44.

The Beehive is about 525 light years away. The bright central part that you see in your binoculare are about 13 light years across. You may see a couple of dozen stars in your binoculars, but scientists using huge telescopes that can see real faint stars have counted over 350 stars in this area, but only aroun 200 are actually part of the cluster.

All these stars were born from the same clouds of gas and dust about 10 million years ago according to astronomers. Open clusters are sometimes referred to as Galactic Clusters because they formed from the material that is floating around on our galaxy.

Brian Cieslak

Horwitz-DeRemer Planetarium

Star charts created using Cartes du Ciel, Binocular image from ‘The Binocular Sky’ website