James Webb Space Telescope Spots Its First Exoplanet

The James Webb Space Telescope has spotted its first exoplanet.

Researchers for the first time confirmed the presence(Opens in a new window) of a planet orbiting another star using the NASA/ESA/CSA optical scope.

Led by Kevin Stevenson and Jacob Lustig-Yaeger of the Johns Hopkins University Applied Physics Lab (APL), the research team chose their target based on data from NASA’s Transiting Exoplanet Survey Satellite (TESS), which hinted at the exoplanet’s existence.

It took only two transit observations for the telescope’s Near-Infrared Spectrograph (NIRSpec) to clearly capture the celestial body. “There is no question that the planet is there,” Lustig-Yaeger said in a statement. “Webb’s pristine data validate it.”

Formally classified as LHS 475 b, the planet is almost exactly the same size as our own, clocking in at 99% of Earth’s diameter. The fact that it is also a small, rocky planet is impressive for the observatory,” according to Stevenson.

This is just one small step for researchers, who don’t yet know if this Earth-sized terrestrial planet has an atmosphere. While Webb is the only operating telescope capable of characterizing such information, it’s still too early to draw any definitive conclusions.

Nevertheless, the team has ruled out certain terrestrial-type atmospheres, including a thick methane-dominated atmosphere, like that of Saturn’s moon Titan. Webb also revealed that the planet is a few hundred degrees warmer than Earth, so the existence of clouds, if found, could suggest a Venus-esque atmosphere, heavy with carbon dioxide and shrouded in a thick haze.

“These first observational results from an Earth-sized, rocky planet open the door to many future possibilities for studying rocky planet atmospheres with Webb,” said NASA’s Astrophysics Division director Mark Clampin. “Webb is bringing us closer and closer to a new understanding of Earth-like worlds outside the Solar System, and the mission is only just getting started.”

LHS 475 b is relatively close to Earth—only 41 light-years away, in the constellation Octans. Researchers are scheduled to obtain additional spectra with further observations this summer.

“This rocky planet confirmation highlights the precision of the mission’s instruments,” Stevenson said. “And it is only the first of many discoveries that it will make.”

“With this telescope, rocky exoplanets are the new frontier,” Lustig-Yaeger added.