How big is the whole universe 1

The Planck mission provides the first overall picture of the cosmos - the scientific harvest can begin

The sky in the microwave range

Paris (France) - With its sensitive antennas, the European space probe Planck has completely scanned the sky in the microwave range and thus provided its first image of the entire cosmos. The astronomers hope that the data will provide new insights into the early days of the universe and the formation of stars and galaxies. Planck was launched on May 14, 2009 and is stationed 1.5 million kilometers from Earth in the opposite direction to the Sun.

The disc of our Milky Way galaxy stretches across the picture as a luminous band. Ribbons of cold dust sticking out of the Milky Way up and down are noticeable - regions in which new stars are formed. Of greater importance to the researchers, however, is the blotchy background above and below the Milky Way. This cosmic background radiation is a holdover from the hot phase of formation of the universe. The scientists hope that its structure will provide an answer to the question of how the Big Bang actually happened.

"This is the moment we built Planck for," explains David Southwood, Science Director at the European Space Agency. "We have not yet given an answer. But we are opening the door to an Eldorado in which researchers can look for nuggets that can lead to a deeper understanding of the origins and development of the cosmos. Now the scientific harvest can begin."

The cosmic background radiation comes to earth equally from all directions, but superimposed on it is the microwave radiation from the Milky Way. The researchers now have to carefully eliminate this local radiation from the image obtained in order to obtain a pure map of the background radiation. The best data so far on background radiation was provided by the American "Wilkinson Microwave Anisotropy Probe", or WMAP for short, launched in 2001. Planck now clearly surpasses WMAP once again: the detectors of the European probe are ten times more sensitive than those of WMAP, Planck also has twice the angular resolution and covers a much larger wavelength range. The cosmologists hope to find evidence of so-called inflation in the Planck data, a short phase immediately after the Big Bang in which the universe expanded rapidly by many orders of magnitude.