For the first time, astronomers have detected water vapor in the atmosphere of an exoplanet. This emerges from a study published in the journal Nature Astronomy (Nature Astronomy: Tsiaras et al., 2019). The so-called Super Earth K2-18b circles around a dwarf star in the constellation Leo, about 110 light-years away from Earth. Exoplanets are located far outside our solar system and are not accessible to humans.
The exoplanet was discovered in 2015 by the US Space Telescope Kepler. The detection of water using the Hubble telescope succeeded, the researchers said. K2-18b probably consists of silicates like the Earth, Mars and Venus, as well as ice.
The exoplanet is at the right distance from its sun, so that life could have formed there. If such planets are too far away from their sun, it is too cold there, they are too close, it gets too hot on the surface, which would make life impossible. An "exoplanet" is considered to be "habitable" if it has the right conditions for life to form on earth: organisms that consist primarily of carbon and water and that use the energy of their sun through photosynthesis.
"Is the earth unique?"
The find does not therefore mean that there actually is life on the distant exoplanet K2-18b. "We can not conclude that liquid water is on the surface of the exoplanet, but I think this is very possible," said co-author Giovanna Tinetti. In addition, on the planet prevail at a temperature that is very similar to that of the earth.
According to the scientists, an exoplanet has never been discovered that fulfills both prerequisites for potential life: the right temperature and water. However, they warned against premature speaking of a second earth. The exoplanet is twice the size of the earth and has eight times the mass. The star that he orbits is also not comparable to our sun.
In addition, it is unclear whether the discovered water actually flow on the surface, it was said by the authors. "Finding water in a potentially habitable, non-Earth world is incredibly exciting," said co-author of the study, Angelos Tsiaras, from University College, London. "It brings us closer to the answer to the fundamental question: is the earth unique?".