- M 44 (NGC 2632) Praesepe or the Beehive Cluster
This mosaiced image of M 44 was created from 5 images— one of the center of the cluster and the other four forming the corners around it. Each of the five images was created from 16 90-second exposures. This mosaicing was necessay because the cluster is too large (1.2 degrees) to be adequately captured in a single image using the SOCO system.
M 44 is one of the closest open clusters to us— only 610 LY away. Since M 44 lies well outside of the stream of the Winter Milky Way, it stands out well from its background. The central part of the cluster has a physical diameter of around 6 LY. If you include the outlying stars spread across the full diameter of the cluster, the physical size increases to around 15 LY. Its age has been estimated to be around 500 to 700 million years, which is about the same age as the Hyades cluster in the constellation Taurus. When the motions of these two clusters are traced back in time, they meet at a common point of origin. Due to its age, M 44 contains a number of red giant stars. It also contains an unusually large number of variable stars.
Charles Messier included it as number 44 in his catalog of "nebulous objects" published in 1769, along with M 42 and M 43 (parts of the Orion Nebula) and M 45 (the Pleiades). There has been some question why he added these objects to his list, since they were already well-known among astronmers and certainly would not be confused with comets. It is likely that he included them to bring his list up to 45 objects. It should be noted that Messier's rival Lacaille published a list of 42 objects in 1755. Perhaps Messier just wanted to out-do his rival.
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