Thursday, 29 October 2015

M3 - Globular Cluster

Type: Globular Cluster  Also known as: NGC 5272

The next item on Messier's vast list is another globular cluster but, despite looking somewhat less 'intense' than the previous example, is actually slightly closer to us at 30,000 light years, slightly larger than M2 at 200 light years across, and consists of substantially more stars - some 500,000, no less. Some of them are red giants (the yellowish ones here) but most are hotter blue giants, many of them variable.

There are actually, at present count, 274 variable stars in M3 which is considerably more than in any other globular cluster, and it's thanks partly to these that it has become one of the best-studied such clusters in our skies. It's not as old as M2 at a mere 8 billion years old (compared to 13) but it's probably a more interesting target for amateur astronomers with decent enough equipment.

Observation: Many consider M3 one of the best clusters in the northern skies for observations. While barely visible with the naked eye, even in superb conditions, it can be spotted with binoculars and observed quite well with an average telescope. It's located in the Canes Venatici constellation and can be found almost exactly halfway between Arcturus and Cor Caroli. While an impressive sight by itself, those with a good telescope may even spot some background galaxies as well.

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