“There is no doubt that the planet is there. Webb’s pristine data validates this.” Jacob Lustig-Yaeger, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, USA, is in no doubt. The James Webbthe best and most sophisticated space telescope of all time, has confirmed its first exoplanet, as the worlds beyond the Solar System are called. Formally classified as LHS 475 b, it is rocky and almost exactly the same size as Earth.
The team chose to observe this target 41 light-years from Earth after carefully reviewing data from NASA’s TESS satellite, which hinted at its existence. Webb’s Near Infrared Spectrograph (NIRSpec) captured the planet “easily and clearly” with just two transit observations (the planet’s passage in front of its star, causing a small ‘eclipse’).
The researchers confirmed that LHS 475 b completes one orbit in just two days. Although it is closer to its star, a red dwarf, than any other world in the Solar System, it is less than half the temperature of the Sun, so it is possible that the planet has an atmosphere.
Among all the operating telescopes, only Webb is capable of characterizing the atmospheres of Earth-sized exoplanets. However, the team has not yet been able to confirm if LHS 475 b has one. If it really exists, they rule out some types, such as a thick methane-dominated shell, similar to that on Saturn’s moon Titan. But it could be found an atmosphere of pure carbon dioxide. The researchers will make new more precise measurements to clarify this point.
warmer than earth
Webb also revealed that the planet is a few hundred degrees warmer than Earth, so if clouds are detected, the researchers could conclude that the planet is more like Venus, that it has an atmosphere of carbon dioxide and is perpetually shrouded. in a thick cloud
For Mark Clampin, director of the Astrophysics Division at NASA headquarters in Washington, “These first results open the door to many future possibilities for studying atmospheres of rocky planets with Webb.” For that reason, “Webb brings us ever closer to a new understanding of Earth-like worlds outside the Solar System, and the mission has only just begun.”
“This rocky planet confirmation highlights the precision of the mission’s instruments,” says Kevin Stevenson of Johns Hopkins. “And it’s just the first of many discoveries it will make,” he adds. Lustig-Yaeger agrees: “With this telescope, rocky exoplanets are the new frontier«.