M110
Andromeda Satellite #2
Elliptical
Properties
Position & Identifiers
Visibility
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About M110
Description
M110 is a dwarf elliptical galaxy and the second-brightest satellite of the Andromeda Galaxy (M31), about 2.7 million light-years from Earth. It spans about 17,000 light-years and is unusual for an elliptical galaxy in that it contains dark dust clouds and evidence of recent star formation. M110 is classified as a spheroidal dwarf galaxy.
Observing Tips
Located about 35 arcminutes northwest of M31's center — visible in the same telescope field. M110 appears as a large, diffuse, oval glow with much lower surface brightness than M32 (M31's other visible satellite). Compare the two: M32 is compact and bright, while M110 is spread out and ghostly. Dark, transparent skies help reveal M110's full extent. Best observed from September through January.
History
First observed by Charles Messier on August 10, 1773 — he even depicted it in a drawing of M31. However, it was not formally added to the Messier catalog until 1966 by Kenneth Glyn Jones, making it the final addition. Caroline Herschel independently discovered it in 1783.
Fun Facts
M110 is the last object added to the Messier catalog (1966) and is unusual among elliptical galaxies for containing dust lanes and populations of young blue stars. Most ellipticals are 'dead' galaxies with no ongoing star formation, but M110 seems to have experienced a small burst of star formation in the relatively recent past. Its interaction with M31 is gradually stripping its outer stars.
Community Photos (1)
Credit: European Space Agency. License: CC BY 2.0. (Wikimedia Commons)
Skybred Feb 28, 2026