Deep Sky

This is an open cluster just 4 degrees south of Sirius, and in the Canis Major constellation.  Note the young bright blue white stars as well as the highlight from some yellow giants.  The brightest being a 4.5 magnitude.  This cluster is approx 2,300 light years from earth and spans some 25 light years.  Astronomers estimate it at some 100 million years old.

It is said that Aristotle was the first to note this cluster in 325 BC, then catalogued by Giovanni Batista Hodierna around 1654 and of course by Messier in 1785.
Date: 10  Feb 12
Images 20-20sec stacked