Explanation:
"Beautiful Nebula discovered between the Balance [Libra] & the
Serpent [Serpens] ..." begins the description of
the 5th entry
in 18th century astronomer Charles Messier's famous catalog of
nebulae and star clusters.
Though it
appeared
to Messier to be fuzzy and round and without stars,
Messier 5 (M5)
is now known to be a globular star cluster,
100,000 stars or more, bound by gravity and packed into
a region around 165 light-years in diameter.
It lies some 25,000 light-years away.
Roaming
the halo
of our galaxy, globular star clusters are ancient
members of the Milky Way.
M5 is one of the oldest globulars, its stars estimated to be nearly
13 billion years old.
The beautiful star cluster is a popular target for
earthbound telescopes.
Even close to its dense core, the cluster's
red and blue giant stars
stand out with yellowish and blue hues in
this sharp color image.
