Last updated on April 17, 2014 at 1:21 EDT
Simulation of cosmic ray background as Planck would see it
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Simulation of cosmic ray background, as Planck would see it

May 24, 2009
The Cosmic Microwave Background is visible in all directions with (almost) the same intensity. This was confirmed by the COBE satellite, which measured (almost) the same temperature of 2.7 Kelvin everywhere on the sky.

However, the very existence of other galaxies points to the fact that there should be very small changes in the measured 'temperature' of the CMB. These changes, or fluctuations, would have provided the seeds for the formation of the galaxies that we see today.

Planck will be able to measure these tiny fluctuations, up to 5 millionths of a degree.