M31: The Andromeda
Galaxy
From NASA’s Astronomy
Picture of the Day
Andromeda is the nearest
major galaxy to
our own Milky
Way Galaxy. Our Galaxy is thought to look much like Andromeda.
Together these two
galaxies dominate the Local
Group of galaxies. The diffuse light from Andromeda is caused by
the hundreds of billions of stars
that compose it.
The several distinct
stars that surround Andromeda's
image are actually stars in our Galaxy that are
well in front of the background object.
Andromeda is
frequently referred to as M31 since it is the
31st object on Messier's
list of diffuse sky objects. M31 is so distant it
takes about two million years for light to reach us from there.
Although visible without
aid, the above image of
M31 was taken with a small telescope. Much about M31 remains unknown,
including how it acquired its unusual double-peaked
center.
