WHEN GALAXIES COLLIDE The Whirlpool Galaxy, the red spiral, and its companion galaxy, NG 5195 are 23 million light-years from Earth - that's relatively close. IRAC shows the warm dust in red, a sign of active star formation probably triggered by a collision between the two galaxies.
This image from NASA's Galaxy Evolution Explorer shows NGC 6744, one of the galaxies most similar to our Milky Way in the local universe. This ultraviolet view highlights the vast extent of the fluffy spiral arms, and demonstrates that star formation can occur in the outer regions of galaxies. The galaxy is situated in the constellation of Pavo at a distance of about 30 million light-years. NGC 6744 is bigger than the Milky Way, with a disk stretching 175,000 light-years across.