Covering a portion of the sky about 55°, the image was obtained by Planck’s High Frequency Instrument at a frequency of 857 GHz (corresponding to a wavelength of 350 micrometers). The dark horizontal band is the plane of our Galaxy, seen in cross-section from our vantage point. The colors represent the intensity of heat radiation by dust.
Image credit: ESA and the HFI Consortium
Note: For more information, see Planck Image of a Region in the Constellation Perseus; also, see New Planck Images Reveal Large-Scale Structure in Milky Way and Planck's View of Orion.