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Constellation In Focus: Hercules
Constellation In Focus: Hercules

The fifth largest constellation in the sky, Hercules is perhaps most famous because of the Great Hercules Cluster, M13, perhaps the most prominent of globulars visible to northern hemisphere observers.

At least 149 globular clusters in the Milky Way have been discovered, and more than 100 are in the NGC-IC catalog. Their distribution forms a spherical halo, centered on the core of our Milky Way. "Globs" are densely packed balls of stars. Up to two million stars can be found bound together with a radius of no more than 100 light years.

The Great Hercules Cluster is visible to the naked eye at dark sites. The glob is about 14 billion years old and contains more than a million suns.

Because of its proximity to M13, M92 is often overlooked even though it's one of the brighter clusters available to northern viewers. One of Johann Elert Bode's discoveries in 1777, it was rediscovered by Charles Messier in 1781 and has been clocked speeding toward us at 112 km/sec.

NGC 6229 is another globular cluster that's worth a look. Mistaken for a nebula by Herschel in 1787, it was revealed to be a "very crowded cluster" in the mid 1800s.

NGC 6210 is a planetary nebula, a sun not unlike our own in the final stages of its life. It has a very high surface brightness and is a good target for high magnification.

July 2006

Date Taken: 05/24/2011
Author: Sean O'Dwyer
Category: Astronomy

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