An active star-formation region in the constellation Orion, as seen by Planck. This long-wavelength image covers a square region of 13 by 13 degrees (which is equivalent to 26 by 26 full moons). It is a three-color combination constructed from three of Planck's nine frequency channels: 30, 353 and 857 gigahertz.
The giant red arc of Barnard's Loop is thought to be the blast wave from a star that blew up inside the region about two million years ago. The bubble it created is now about 300 light-years across.
Image credit: ESA/LFI & HFI Consortia› Larger image