At a distance of 41 light-years from Earth, a kind of twin of our planet is moving around its star: the exoplanet LHS 475 b has a diameter that corresponds to 99 percent of that of the Earth. And he is the first exoplanet that the James Webb Space Telescope (JWST) has detected. This is what ESA and NASA report on their pages.
The Transiting Exoplanet Survey Satellite (Tess) of NASA already provided initial indications of the celestial body, but only with the help of recordings in the nearby infrared by the JWST ultimately the existence of the exoplanet was confirmed. He circles a red dwarf in the constellation octant in just two days, so that the planet is significantly hotter than the earth. So it is not in a habitable zone. Thanks to the highly developed measuring instruments of the telescope, only two transit phases of LHS 475 B were sufficient for the detection. "The fact that it is a small rock planet is an impressive observation," says Kevin Stevenson from John's Hopkins University Applied Physics Laboratory in Laurel, which was involved in the evaluation.
The team tried to determine whether the planet has an atmosphere and how it is composed by analyzing the transmission spectrum. "The telescope is so sensitive that it can easily detect a number of molecules, but we can't draw any definitive conclusions about the planet's atmosphere yet," says Erin May, also from the Johns Hopkins University Applied Physics Laboratory. However, the scientists can already rule out that the planet has a dense, methane-rich gas shell, as is the case with Saturn's moon Titan, for example.
However, the working group cannot rule out a thin atmosphere that (almost) is made of carbon dioxide. This is extremely difficult to prove, the participants write.
Webb also proved that the planet is a few hundred degrees warmer than the Earth. So, if clouds are detected, the planet would be more like Venus, which has a very dense carbon dioxide atmosphere and is constantly shrouded in thick clouds. "We are at the very beginning of the exploration of small, rocky exoplanets," says Jacob Lustig-Yaeger from the Johns Hopkins University Applied Physics Laboratory. "We have only just begun to scratch the surface of what their atmospheres might look like.«
