M7 (NGC 6475) -- Open Cluster in Scorpius
“The Cloudy Ones Which Follow the Sting” – M7
Long before the Messier compiled his list of Deep Sky Objects and even before the
invention of the telescope, the Open Clusters of M6 and M7 were known as fuzzy
patches near the tail of the heavenly scorpion. The above quote is from Ulug Beg’s Star
Catalogue (1437). Today they are known as two of the largest and brightest of the star
clusters that can be seen in the night sky.
M6 and M7 are only about 3 ½ degrees apart in the night sky and together make a
stunning pair-of-clusters in binoculars. M6 has dimmer stars than M7, but then again M6
is twice the distance of M7. Since M6 is also twice the size of M7 they both appear to
occupy the same amount of space (each about equal to the Full Moon) as seen from
earth. As the quote implies they are easily found following the sting (marked by the stars
Shaula & Lesuth) at the end of the Scorpion’s tail (Constellation Scorpius).
M7 is best viewed in binoculars or a wide-field telescope. The Open Cluster contains
over 80 stars brighter than 7th magnitude which shine bright in binoculars even from
Maryland where the cluster is low in the southern sky.