Such pictures of the planet HD 189733b are so far only possible in the imagination of artists. Image: Giovanna Tinetti / ESA / NASA
Read aloud An international research team first discovered organic molecules on a planet outside our solar system. In the atmosphere of the planet HD 189733b, the researchers traced traces of methane? a hydrocarbon that is also found on celestial bodies such as Saturn's moon Titan. At the same time, Research Director Mark Swain of the US Space Agency Nasa and his colleagues confirmed the existence of water molecules in the atmosphere of HD 189733b. Earlier results had already indicated their presence. However, the researchers put a stop to speculation about possible life on the planet: on HD 189733b, it is far too hot for any known life form. Methane is the starting point for many organic compounds and is formed, among other things, by biological processes, such as in the digestive tract of cattle. The scientist Giovanna Tinetti of the European Space Agency ESA, which was also involved in the study, but does not believe in the existence of life on HD 189733b: "It is very unlikely that cows can survive here, " she says jokingly with the view temperatures. These can reach up to 900 degrees Celsius on the extrasolar planet? That's why this planet has the nickname "Hot Jupiter". The reason for these high temperatures is the proximity of HD 189733b to its parent star. In only two days, he completes a cycle around the star named HD 189733 A. The planet of the size of Jupiter is located about 63 light-years from Earth in the constellation Fuchs.

The orbits helped the researchers investigate: whenever the exoplanet moved from Earth's front of its parent star, researchers could use the Hubble Space Telescope to gather data about the atmosphere of HD 189733b. To do this, they analyzed the specific composition of the light that was taken during the planetary transit. The different chemicals in the atmosphere leave a kind of fingerprint in the light spectrum. Thus, the researchers could also prove the existence of water on HD 189733b. This had been speculated since 2007, when the Spitzer Space Telescope had taken pictures of the exoplanet.

Swain sees the results of the study as a validation of the approach: "Infrared spectroscopy is the key to studies of this kind because it is best at detecting molecules." He also wants to use spectroscopy to enhance the atmosphere of Earth-like planets who are moving in a life-friendly zone around their fixed star. One day, it would be possible to study air pressure, temperature, cloud coverage and chemical composition of planets, Swain hopes.

Mark Swain (Jet Propulsion Laboratory of NASA) et al .: Nature, Vol. 452, p. 329 ddp / Markus Zen's ad


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