Planck's Microwave Sky

This multi-color all-sky image of the microwave sky has been synthesized using data spanning the full frequency range of Planck, which covers the electromagnetic spectrum from 30 to 857 GHz.

The grainy structure of the CMB [Cosmic Microwave Background], with its tiny temperature fluctuations reflecting the primordial density variations from which the cosmic web originated, is clearly visible in the high-latitude regions of the map, where the foreground contribution is not predominant.

A vast portion of the sky, extending well above and below the galactic plane, is dominated by the diffuse emission from gas and dust in the Milky Way, which shines brightly at Planck's frequencies. While the galactic foreground hides the CMB signal from our view, it also highlights the extent of our Galaxy's large-scale structure and its emission properties.

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This image is derived from data collected by Planck during its first all-sky survey, and covers about 12 months of observations.

Note: Because of the manner in which all the channels have been combined to produce this image, the colors no longer represent accurately the brightness at each frequency. The angular resolution of this image has been reduced by a factor of around three from its sharpest rendition, to better match it to a typical viewing screen.

Photo credit: ESA, HFI and LFI consortia

Note: The Minister is not happy with the definitions available on the Internet for "diffuse emission." The closest definition found says, "Emitters of radiation that covers a relatively large part of the sky are called extended sources." Diffuse in this case equates to "extended," meaning, the source of the radiation is not localized. A star is an example of a localized source of radiation; the radiation comes from a specific, discrete source. (Radiation may refer to any and/or all wavelengths of the electromagnetic spectrum.) Diffuse emission, on the other hand, refers to the emission of radiation from a source that is much broader than a localized emitter; indeed, the emissions may come from multiple sources that are either too numerous or too indistinct for scientific instruments to focus on discrete localized sources of emission. Examples of diffuse emission include nebulae and galaxies.