Messier 6, the Butterfly cluster, and Messier 7, Ptolemy's cluster, are two beautiful open clusters in Scorpius. M6, at upper right, shines at magnitude 4.2 and has an apparent diameter of 33 arcminutes, nearly as large as the full moon. It contains 80 stars and is 1,600 light-years from Earth. M6 was discovered by Hodierna before 1654 and is 50 million to 100 million years old. M7, at lower left, shines at magnitude 3.3, has an apparent diameter of 75 arcminutes, and lies 800 to 1,000 light-years from Earth.