One of our closest galactic neighbors shows its awesome beauty in this new
image from NASA's Spitzer Space Telescope. M33, also known as the
Triangulum Galaxy, is a member of what's known as our Local Group of
galaxies. Along with our own Milky Way, this group travels together in the
universe, as they are gravitationally bound. In fact, M33 is one of the
few galaxies that is moving toward the Milky Way despite the fact that
space itself is expanding, causing most galaxies in the universe to grow
farther and farther apart.
When viewed with Spitzer's infrared eyes, this elegant spiral galaxy
sparkles with color and detail. Stars appear as glistening blue gems
(several of which are actually foreground stars in our own galaxy), while
dust rich in organic molecules glows green. The diffuse orange-red glowing
areas indicate star-forming regions, while small red flecks outside the
spiral disk of M33 are most likely distant background galaxies. But not
only is this new image beautiful, it also shows M33 to be surprising
large—bigger than its visible-light appearance would suggest. With
its ability to detect cold, dark dust, Spitzer can see emission from
cooler material well beyond the visible range of M33's disk. Exactly how
this cold material moved outward from the galaxy is still a mystery, but
winds from giant stars or supernovas may be responsible.
M33 is located about 2.9 million light-years away in the constellation
Triangulum. This is a three-color composite image showing infrared
observations from two of Spitzer instruments. Blue represents combined
3.6- and 4.5-micron light and green shows light of 8 microns, both
captured by Spitzer's infrared array camera. Red is 24-micron light
detected by Spitzer's multiband imaging photometer.