By measuring with an accuracy of temperature fluctuations and polarization of the CMB, the Planck satellite will allow a detailed picture of the first moments and content of the Universe.
Alain Riazuelo
On 16 April, an Ariane-V will carry on board two satellites of the European Space Agency, eagerly awaited by astrophysicists and cosmologists: the Herschel space telescope and the Planck satellite.
With a mirror 3.5 meters in diameter, Herschel will be the largest space telescope ever launched. It will observe the universe in the infrared and submillimetre wavelengths. The Planck satellite, it will be to observe with unprecedented accuracy the CMB, the image of the Fossil Universe. We will provide a clearer picture of the content, origin and evolution of the Universe. Let's see how.
All astronomers now agree on one point: the universe is expanding. The galaxies are moving away from each other in all directions, even faster than they are distant. If we go back the expansion of this film in reverse, the Universe was denser and hotter in the past. This is the scenario of the Big Bang, which states that the universe came from a state of density and temperature is incredibly high about 13.7 billion years, and has since cooled and diluted at the rate the cosmic expansion.
Who says hot and dense that light. At the time of the Big Bang, the universe was bathed in intense radiation. Today, that primordial radiation was diluted and cooled by the expansion of the universe, but this "vanished brilliance of the formation of worlds," to quote the Belgian cosmologist Georges Lemaître, still exists in the form of a very cold radiation, called cosmic microwave background. The temperature of the background is now 2.7 degrees Kelvin, or about - 270.5 ° C.
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