Praesepe refers to an open cluster of stars in the dim constellation Cancer, which lies between two brighter constellations, Gemini and Leo. Its Latin name means "hive" or "manger." Today it is more commonly known to English-speaking people as the Beehive Cluster. The Beehive Cluster is also known by designations in several common catalogs of deep sky objects: In the Messier Catalog it is listed as M44; in the New General Catalog, it is NGC2632, and in the Collinder Catalog, it is Col189.
The term "open cluster" refers to a group of stars of similar age, formed from the same cloud of material, and maintaining a loose gravitational bond. Astronomers currently believe the Beehive Cluster is nearly 600 light years away and more than 700 million years old.
The Beehive Cluster, which can be seen with unaided eyes, was known to ancient observers. Under dark skies, it appears as a blur or smudge. Binoculars easily reveal a swirling swarm of stars. Modern researchers believe than the collection contains about 1,000 stars. In 2012, NASA's Jet Propulsion Laboratory announced the discovery of two "hot Jupiter" type planets orbiting different stars within the cluster. The planets were dubbed Pr0201b and Pr0211b. For more information, see "First Planets Found Around Sun-Like Stars in a Cluster."
If you'd like to view the Beehive Cluster for yourself and you need help finding it, you can download a free Evening Sky Map from SkyMaps.com. And, if you'd like to learn more about astronomy, the following titles from the Pier Press Bookstore can help you get started:
- Find the Constellations, by H.A. Rey, for young stargazers in grades 4 to 6.
- The Stars: A New Way to See Them, by H.A. Rey, for beginning stargazers aged 12 and up.
- Nightwatch: A Practical Guide to Viewing the Universe, by Terence Dickinson, a great introduction to stargazing for adults.
This article originally appeared in the April 2016 issue of Observations: A Pier Press® Newsletter. If you're not already a subscriber, click here to sign up. It's free.