thumb|Map showing the location of M44 in the constellation of Cancer

The Beehive Cluster (also known as Praesepe (Latin for "manger", "cot" or "crib"), M44, NGC 2632, or Cr 189) is an open cluster in the constellation Cancer. One of the nearest open clusters to Earth, it contains a larger population of stars than other nearby bright open clusters holding around 1,000 stars. Under dark skies, the Beehive Cluster looks like a small nebulous object to the naked eye, and has been known since ancient times. Classical astronomer Ptolemy described it as a "nebulous mass in the breast of Cancer". It was among the first objects that Galileo studied with his

telescope.

Its age and proper motion coincide with those of the Hyades, suggesting they may share similar origins. Both clusters also contain red giants and white dwarfs, which represent later stages of stellar evolution, along with many main sequence stars.

The distance to M44 is often cited to be between 160 and 187 parsecs (520–610 light years), but the revised Hipparcos parallaxes (2009) for Praesepe members and the latest infrared color-magnitude diagram favors an analogous distance of 182 pc. There are better age estimates of around 600 million years (compared to about 625 million years for the Hyades). The diameter of the bright inner cluster core is about 7.0 parsecs (23 light years). Wilhelm Schur, as director of the Göttingen Observatory, drew a map of the cluster in 1894.left|thumb|[[Wilhelm Schur|Wilhelm Schur's map of the Beehive Cluster in 1894]]Ancient Greeks and Romans saw this object as a manger from which two donkeys, the adjacent stars Asellus Borealis and Asellus Australis, are eating; these are the donkeys that Dionysos and Silenus rode into battle against the Titans.

Hipparchus (c.130 BC) refers to the cluster as Nephelion ("Little Cloud") in his star catalog.), describing it as "The Nebulous Mass in the Breast (of Cancer)". Aratus (c.260–270 BC) calls the cluster Achlus or "Little Mist" in his poem Phainomena. Bayer also cited the name Melleff or Meeleph for the cluster, from Arabic Al Ma'laf, the Stall; This means that bright massive stars are concentrated in the cluster's core, while dimmer and less massive stars populate its halo (sometimes called the corona). The cluster's core radius is estimated at 3.5 parsecs (11.4 light years); its half-mass radius is about 3.9 parsecs (12.7 light years); and its tidal radius is about 12 parsecs (39 light years).

So far, eleven white dwarfs have been identified, representing the final evolutionary phase of the cluster's most massive stars, which originally belonged to spectral type B.

In 2016 additional observations found a second planet in the Pr0211 system, Pr0211 c. This made Pr0211 the first multi-planet system to be discovered in an open cluster.

  • M44 Photo detail Dark Atmospheres
  • Messier 44, SEDS Messier pages
  • NightSkyInfo.com – M44, the Beehive Cluster
  • Praesepe (M44) at Constellation Guide