Spring Gems Spring Forth

Spring Gems Spring Forth
By Rod Kennedy

Spring, like fall, is a transitional period in the sky.  The bright stars of winter are slowly setting in the West, and the bright constellations of summer have not yet risen in the East.  Even the visible arms of the Milky Way spend much of the season close to the horizon, making it difficult to observe.  Yet, before winter bids us its last farewell, there are a few gems left to be found, all of them open star clusters.  Time to get out those binoculars and start scanning the skies.

The most famous star cluster is M45, the Pleiades or Seven Sisters in the shoulder of Taurus the Bull.  Through binoculars, the Pleiades reveals not seven stars but dozens.  However, like most star clusters, this famous group is actually made up of hundreds of stars.

Moving east and slightly north along the ecliptic we find M35, about half way between Aldebaran and Pollux.  M35 is a beautiful cluster that vaguely resembles the W shape of Cassiopeia. Almost directly below M35 is NGC 2158.  NGC 2158 provides an interesting contrast from the much larger cluster above it.  Continuing along the ecliptic we find M44, the Beehive cluster.  The Beehive is also known as the Praesepe or Manger.  This cluster is located in Cancer the Crab and is difficult to spot under the light polluted skies of a city.  Despite the challenge of locating this little cluster, it is a wonderful sight in a pair of binoculars or a telescope.  Look for M44 at the point of an equilateral triangle between the stars Procyon and Pollux.

Just a little south of M44 is M67, sometimes known as the King Cobra cluster.  This designation is probably in reference to the pattern formed by the brightest stars of the cluster, which do indeed resemble the pattern on the hood of a cobra.  M67 is located about half way between Procyon and Regulus.  Another nearby cluster is M48.  M48 is a little south and west of M67, roughly half way between Procyon and Alphard in Hydra.  Both M48 and M67 are about three times further from Earth than M44, being approximately 1500 light years away.

Moving low in the southern sky, just to the southeast of Sirius we find M41 the Little Beehive cluster.  As its name implies M41 does resemble the larger cluster in Cancer only smaller.  About the same distance north and east of Sirius we find M46 and M47.  M47 is filled with several brilliant stars while M46 is made up of smaller, dimmer stars.  However, M46 has an additional interesting feature, namely a small planetary nebula which seems to be embedded within the cluster.  The nebula is probably not associated with the cluster in any way but seeing the two together provides a great chance to see two different kinds of objects at the same time.

By now it should be easy to see that these open star clusters are located along the arm of the Milky Way that we see from Earth.  This is not unusual.  The arms of spiral galaxies typically have lots of these open or galactic star clusters.  Hence we see very few open clusters in Spring and Fall, as the Milky Way lies close to the horizon in those seasons.

Spring is a wonderful time of renewal.  We see beauty renewing itself all around us.  What better way to renew our enthusiasm for star gazing than by getting out on a pleasant spring evening and discovering the beauty of open star clusters?

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