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uni'wissen 01-2014_ENG

“Our main goal is to study the composition of the atmospheres of exoplanets.” If there is life on other planets, Prof. Dr. Svetlana Berdyugina might just be the first person to discover it. The astrophysicist measures the polarization of light reflected from planets outside of our solar system – so-called exoplanets. In 2008 she and her team, then at ETH Zurich, Switzerland, succeeded in presenting the first evidence of light hitting one of these planets – more than 1.5 billion times farther away than the Moon. Today Berdyugina conducts her research at the Kiepenheuer Institute for Solar Physics in Freiburg and serves as a professor at the Institute of Physics of the University of Freiburg. Her next goal is to use polarization to find out what substances are present in the atmospheres of exoplanets. Perhaps she will also find molecules produced by living organisms there. Invisible Properties of Light The European Research Council (ERC) has furnished Berdyugina with a five-year Advanced Grant worth 2.5 million euros. “During the funding period we want to build a polarimeter that is even more sensitive. This will allow us to detect molecules in a planet’s atmosphere,” says the researcher. This instrument can measure the light of planets located – as seen from the Earth – directly next to their home star on the course of their orbit around it. Other methods only work when the planet is passing directly in front of its sun. The polarimeters Berdyugina and her team are developing will need to be very sensitive, because the quantity of light reflected from the planet is infinitesimal compared to that emitted directly by the star. The measuring instruments filter out of the blindingly bright light of the star the tiny bit of light that has traveled through the planet’s atmosphere. In doing so, they make use of a property of light that is measurable, although it is not visible – its polari- zation. Polarization describes the direction in which light waves strike out. Light races through the cosmos in the form of waves. These waves oscil- late crosswise or edgewise or helically in relation to the direction in which they spread. In the direct With the help of a prototype of the “Innovative Polarimeter” (left picture), the researchers studied pigments typically used by bacteria for photosynthesis – such as chlorophyll, carotenoids, and anthocyanin (right picture, from left). Photos: Svetlana Berdyugina 5