M31
Andromeda Galaxy
Messier 31 (M31), popularly known as the Andromeda Galaxy, is the closest major spiral galaxy to our own Milky Way, located approximately 2.5 million light-years away from Earth. It is the largest member of our Local Group of galaxies and is currently on a collision course with the Milky Way, with a merger expected in about 4 to 4.5 billion years.
Key Characteristics
Size and scale:
Spans roughly 200,000 light-years in diameter, which is significantly larger than the Milky Way. It contains an estimated one trillion stars, roughly double our galaxy’s population.
Appearance:
Features a bright yellow nucleus dominated by older stars, surrounded by winding dust lanes and spiral arms dotted with young, hot blue star clusters.
Satellite galaxies:
M31 is orbited by at least 35 dwarf galaxies, the most prominent being M32 and M110, both of which are visible in many wide-field amateur photographs.
Black hole:
At its center lies a supermassive black hole, designated M31, which is millions of times the mass of our Sun.