The Messier Ten Minute Challenge

M4 - Globular Cluster in Scorpius

Messier 4 (NGC 6121) lies at a distance of about 7,200 light years and
as such is one of the nearest globular clusters. Messier was the first
person to resolve it into stars and M4 was the only globular cluster
where he succeeded in doing this. M4 is heavily obscured by
interstellar dust that both reddens and dims the light we see.

http://www.martin-nicholson.info/ten...allenge/m4.htm

Martin Nicholson, Daventry, England.

My website is at http://www.martin-nicholson.info/1/1a.htm
My informal Astronomical Blog is at http://ukastronomy.livejournal.com/