M33: Spiral Galaxy in Triangulum
Credit & Copyright:
Robert Gendler
The small constellation
Triangulum
in the northern sky harbors
this magnificent face-on spiral galaxy, M33.
Its popular names include the Pinwheel Galaxy or just
the Triangulum Galaxy.
M33's diameter spans over 50,000 light-years, making it third largest in
the Local
Group of galaxies after the Andromeda Galaxy (M31), and our
own Milky Way.
About 3 million light-years from the Milky Way, M33
lies very close to the Andromeda Galaxy and
observers
in these two galaxies would likely have spectacular views of
each other's grand spiral star systems.
As for the view from planet Earth, this
sharp
27 frame mosaic of M33 nicely shows off blue star clusters
and pinkish star forming regions which trace the galaxy's
loosely wound spiral arms.
In fact, the cavernous NGC 604 is the brightest
star forming region seen here, visible
along an arm arcing above and to the right
of the galaxy center.
Like M31, M33's population of well-measured variable stars
have helped make this nearby spiral a
cosmic
yardstick for
establishing
the distance scale of the Universe.