Explanation:
A mere 2.5 million light-years away, the Andromeda Galaxy really is
just next door as large galaxies go.
So close, and spanning
some 260,000 light-years, it took 11 different
image fields from the
Galaxy Evolution Explorer (GALEX) satellite's
telescope to produce this gorgeous portrait of the spiral galaxy in
ultraviolet light.
While its spiral arms stand out
in visible light images of Andromeda
(also known as M31), the arms look more like rings in
the
GALEX ultraviolet view, dominated by hot, young, massive stars.
As sites of intense star formation, the rings have been interpreted as
evidence Andromeda collided with its smaller neighboring elliptical
galaxy M32 more than 200 million years ago.
The large Andromeda galaxy
and our own Milky Way are the dominant members of the
local
galaxy group.
