The M7 Open Star Cluster in Scorpius
M7 is one of the most prominent
open clusters
of stars on the sky.
The cluster, dominated by bright blue
stars,
can be seen with the naked eye in a dark sky
in the tail of the constellation of
Scorpius.
M7 contains about 100 stars in total,
is about 200 million years old, spans 25
light-years across, and lies about 1000 light-years away.
This color picture was taken recently at the
Kitt Peak
National Observatory in
Arizona,
USA as part of the
Advanced Observers Program.
The M7 star cluster
has been known since ancient times, being noted by
Ptolemy in the year 130 AD.
Also visible is a
dark dust cloud
near the bottom of the frame,
and literally millions of unrelated stars
towards the Galactic center.