It took more than 200 years to find out, but a globular cluster discovered in 1778 by comet-hunter Charles Messier turned out to be the first such star swarm located outside the Milky Way. As astronomers discovered in 1994, the cluster, known as M54 in Messier’s famous catalogue, is actually located some 90,000 light years away in the Sagittarius Dwarf Elliptical Galaxy, about three times farther than Earth is from the center of the Milky Way. But if you wait a while – a very long while – M54 will become part of Earth’s galaxy as the Sagittarius dwarf slowly merges with the larger body. This photograph of M54 was taken in 2011 by the Hubble Space Telescope’s Advanced Camera for Surveys.
Owls may be scarce near your favourite viewing spot, but the Northern Hemisphere spring sky contains one celestial owl that you can track down in small telescopes – Messier 97 (NGC 3587). Commonly called the Owl Nebula, M97 is a planetary nebula discovered by Pierre Méchain in 1781 that is currently ideally placed for observation almost overhead at nightfall in the constellation of Ursa Major, the Great Bear.