Ptolemy's Cluster

open star cluster · M7 · in Scorpius

900 light-years from Earth

A bright cluster by the tail of Scorpius, easy to see with the naked eye and the farthest south of all the Messier objects. Ptolemy described it nearly 1,900 years ago as a nebula following the sting of Scorpius.

• 900 light-years (Gaia) · its stars spread over about 45 light-years
• about 220 million years old · 600 of its stars as Gaia measured them

kind

nebula · star cluster

catalogue

M7 · NGC 6475

size

44 light-years across