On a perfectly clear, moonless night, the Andromeda galaxy can just barely be seen by the naked eye. So it is likely that ancient astronomers knew of its existence, but did not understand what it was. According to French astronomer Charles Messier, who put the great nebula in Andromeda as the thirty-first object in his famous Messier Catalog, the first European astronomer who discovered Andromeda was Simon Marius. Marius observed the Andromeda galaxy through a telescope in 1612; he was probably the first person to do so. According to non-European records, however, the ancient Persian astronomer Al-Sufi observed the Andromeda galaxy as early as 905 C.E. without the aid of a telescope. Al-Sufi called it the “little cloud.”