Open Cluster M21

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Messier 21

Open Cluster M21 (also known as Messier Object 21 or NGC 6531) is an open cluster in the constellation Sagittarius. It was discovered and catalogued by Charles Messier on June 5, 1764. M21 is a relatively young cluster of a mere 4.6 million years of age and contains about 57 stars. External links [Messier 21, SEDS Messier pages]   From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating. All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details. Search Titles 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ? E-mail this article to: Personal Message: