Just Visiting This Planet by Neil de Grasse Tyson

Author:Neil de Grasse Tyson [Tyson, Neil de Grasse]
Language: eng
Format: epub, mobi
Tags: Astronomy, Science
ISBN: 9780307784094
Publisher: Crown/Archetype
Published: 1998-01-02T00:00:00+00:00

Dear Merlin,

I would like to know what these “M” designations are in globular cluster names, for example M15 or M54. Are they just numbers given to these objects by figuring their distance?

RENEE TINSLEY

STOCKTON, CALIFORNIA

It was the year 1771 when the French astronomer Charles Messier published his first list of fuzzy-looking objects in the sky (stars, clusters, and nebulas). His intent was to provide a false-alarm list for comet hunters.

Just over one hundred objects have his numerical classification. Some famous ones are Messier 31 (the Andromeda galaxy), Messier 13 (the Hercules globular cluster), Messier 42 (the Orion Nebula), and Messier 1 (the Crab Nebula). Some less-than-famous objects are Messier 102 (an accidental repeat of Messier 101) and Messier 91 (it does not exist).

For brevity, the essier is often dropped, so that one simply writes M before the number.

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