M31 (Andromeda Galaxy)
The Nearest Spiral Galaxy to Earth
M31, or the Andromeda Galaxy, is a spiral galaxy approximately 2.537 million light-years from Earth. It is the largest galaxy in the Local Group, which includes our Milky Way. The Andromeda Galaxy has been known since ancient times and is one of the few galaxies visible to the naked eye from Earth.
Key Facts
Distance from Earth
Approximately 2.537 million light-years
Size
About 220,000 light-years in diameter
Visibility
Naked eye visible; appears as a faint smudge in dark skies
Best Viewing Season
Late summer to fall (August to November)
Ideal Viewing Time
After sunset, when it climbs higher in the sky
Best Season
Late summer to early winter (August to November)
How to Find It
To locate M31, find the Great Square of Pegasus. The galaxy is situated about 5 degrees north of the star Alpheratz, the northeastern corner of the square. Use binoculars or a small telescope for better visibility.
Observing Tip
For astrophotographers, use a wide-angle lens and take long exposure shots to capture the detail and structure of the galaxy. A tracking mount is recommended for exposures longer than 30 seconds to avoid star trails. Take multiple exposures to stack and enhance details in post-processing.