Date: 17 Sep 2009
Satellite: Planck
Depicts: Mosaic of maps at 9 different frequencies, showing part of the Milky Way
Copyright: ESA, LFI & HFI Consortia (Planck)

The above mosaic of maps zooms in on a small part of the First Light Survey, in which our own Milky Way shines very brightly. The nine panels show a 20°×20° map of the emission imaged by Planck in each of the nine frequencies that it is sensitive to: 30 GHz (top left) to 857 GHz (bottom right). Each strip is slightly offset from the others due to the arrangement of the detectors in the focal plane.

At low frequencies electrons in the Milky Way emit radio waves as they interact with gas and the magnetic field; at high frequencies it is dust that radiates heat. At each frequency a different mix of radiation processes contributes to the structure visible in the images; the combination of frequencies provides a rich source of information on the physics of our Milky Way – much of it never available until now.

(Note that each panel is available as a separate image - see Related Images.)