This combined image of radio and visible light observations of the faint galaxy known as M33 looks like lace hanging in the sky. Also known as the Triangulum Galaxy, it is part of the Local Group of galaxies which includes the Andromeda Galaxy and the Milky Way. M33 is over thirty thousand light years across and more than two million light years away. The optical data in this image (mostly white) show the many stars within the galaxy as well as reddish star forming regions that are filled with hot hydrogen gas. The radio data (colored pink) from the Very Large Array (VLA) reveal the cooler hydrogen gas in the galaxy, gas which cannot be seen with an optical telescope. Mergedr, the radio and optical images show a more comprehensive view of star formation in this galaxy.
Image Credit: NRAO