Echoes of the Big Bang: Telescope captures 'oldest light' in the cosmos


THE EUROPEAN Space Agency (ESA) has released the first whole-universe image captured by the Planck satellite. Launched in 2009, its mission is to help cosmologists understand the very earliest years of the universe and explain why it is shaped the way it is today.

The striking image was released yesterday by ESA at the EuroScience Open Forum in Turin. It is the first of four or five full-sky surveys to be delivered by the satellite which orbits a point in space 1.5 million km away from Earth.

If nothing else, it proved that all systems on board Planck are operating properly, Prof Nazzareno Mandolesi of the Italian National Institute of Astrophysics told the meeting in Turin. “The satellite is very healthy, the instruments are working perfectly.”

The satellite gathers monumental amounts of information but not of a kind that you can see. Instead of capturing visible wavelengths it sees only in the microwave range, something that enables it to read one of the most important cosmological clues about the origins of the universe, the cosmic microwave background.

This is a very faint heat signature left behind when the universe was formed in the Big Bang.

This involved a massive release of energy that changed into the matter in the universe we see today.

The satellite can pick up this faint heat signal even though it registers at less than 270 degrees below zero. Achieving this is akin to trying to feel the heat from a candle placed a mile away. Even so, being able to see that signal is very important because it tells scientists about a time just 379,000 years after the Big Bang, Prof Mandolesi said.

The heat from the Big Bang spread out in all directions and was intensely hot but, as it expanded, it cooled. The cooling was not uniform, however, and small hot spots formed. The temperature variations acted like little seeds where the matter we see in the universe today as galaxies, first started to cluster, he explained.

The Planck satellite can see the faint remnants of this temperature difference in the cosmic microwave background, and so can read where matter began to lump together.

Not all of the hot spots have matter associated with them today but many do, he said. It was not a one-for-one distribution, rather a physical process, he said.

Even so, it will help scientists work out why the universe eventually took the shape and structure it now has.

The data analysis of this first full survey by Planck will not be complete for about two years however, such is the volume of data to be studied.

The image shows two things, a side view of our Milky Way galaxy in the foreground, and the cosmic microwave background behind it. The galaxy shows as blue and white while the microwave background shows as red.

The line across the centre is the densely populated central slice of the galaxy.