(See description below)
"Triangulum" Galaxy M33
This magnificent face-on spiral galaxy, M33, resides in the small constellation Triangulum in the northern sky harbors . Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33's diameter spans over 50,000 light-yearsabout one-quarter the diameter of our Milky Way galaxy. It is the third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and the 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 galaxy spans an angle about twice that of the full Moon. The above image 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.