M100 (NGC 4321) -- Spiral Galaxy in Coma Berenices
M100 is only 1 ½ degrees from M99, so both galaxies are often visited on the same
night by amateur astronomers. Both are large face-on Spiral Galaxies (equal in size
to the Milky Way Galaxy). Stephen O’Meara is correct when he points out in his
Messier Book that they are mirror images of each other. In my 155mm refractor, from
the deck of my house, I can not make out any detail in either galaxy except for a
brightening at their galactic cores. M100 is slightly brighter but it is not noticeable. It
is the brightest spiral galaxy in the Virgo Cluster as seen from Earth.