Andromeda Galaxy (M31)
The nearest spiral galaxy to the Milky Way.
The Andromeda Galaxy (M31) is a spiral galaxy approximately 2.537 million light-years from Earth and is the nearest large galaxy to the Milky Way. It is part of the Local Group, which includes over 54 galaxies. The Andromeda Galaxy is visible to the naked eye, making it a popular target for amateur astronomers and astrophotographers alike.
Key Facts
Distance from Earth
Approximately 2.537 million light-years
Diameter
About 220,000 light-years
Apparent Magnitude
+3.44 (naked-eye visible)
Constellation
Andromeda
Total Stars
Estimated 1 trillion stars
Best Season
M31 is best viewed in the Northern Hemisphere from late summer to early winter (August to December). Peak visibility is usually around October.
How to Find It
To locate M31, first find the Great Square of Pegasus. From the top left star (Markab), draw an imaginary line to the bottom left star (Scheat) and extend it approximately halfway between them. M31 is situated slightly above this line. Alternatively, the star Alpheratz (α Andromedae) can be used as a reference point; it is located at the intersection of the Andromeda and Pegasus constellations, and M31 is just north of it.
Observing Tip
For the best views, find a dark location away from city lights. Use a pair of binoculars or a small telescope to appreciate its structure. For astrophotography, use a stable mount and long exposure times to capture details such as the galaxy's core and any visible dust lanes.