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 (many
of which are actually foreground stars in our own galaxy), while dust in
the spiral disk of the galaxy glows pink and red. 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 composite image was taken by Spitzer's infrared array
camera. The color blue indicates infrared light of 3.6 microns, green
shows 4.5-micron light, and red 8.0 microns.