M91

barred spiral galaxy · Virgo Cluster · in Coma Berenices

52.8 million light-years from Earth

The missing Messier object. Messier wrote down a wrong position for it in 1781, and for almost two centuries no one could be sure which galaxy he meant. In 1969 William C. Williams, an amateur astronomer in Texas, showed that Messier had measured its position from M89 but worked it out as if from M58, and so found it: NGC 4548.

• 52.8 million light-years (Cepheids) · about 84,000 light-years across
• it has lost most of its hydrogen; what is left lies in a ring round its bar

kind

galaxy

catalogue

M91 · NGC 4548

size

84,000 light-years across