Free Astronomy Magazine March-April 2023

43 ASTRO PUBLISHING Titan.” The team also notes that while it’s possible the planet has no atmosphere, there are some atmos- pheric compositions that have not been ruled out, such as a pure car- bon dioxide atmosphere. “Counter- intuitively, a 100% carbon dioxide atmosphere is so much more com- pact that it becomes very challeng- ing to detect,” said Lustig-Yaeger. Even more precise measurements are required for the team to distin- guish a pure carbon dioxide atmos- phere from no atmosphere at all. The researchers are scheduled to ob- tain additional spectra with upcom- ing observations this summer. Webb also revealed that the planet is a few hundred degrees warmer than Earth, so if clouds are detected, it may lead the researchers to con- clude that the planet is more like Venus, which has a carbon dioxide atmosphere and is perpetually shrouded in thick clouds. “We’re at the forefront of study- ing small, rocky exoplanets,” Lustig- Yaeger said. “We have barely begun scratching the surface of what their atmospheres might be like.” The researchers also confirmed that the planet completes an orbit in just two days, information that was al- most instantaneously revealed by Webb’s precise light curve. Although LHS 475 b is closer to its star than any planet in our solar system, its red dwarf star is less than half the temperature of the Sun, so the re- searchers project it still could have an atmosphere. The researchers’ findings have opened the possibilities of pinpoint- ing Earth-sized planets orbiting smaller red dwarf stars. “This rocky planet confirmation highlights the precision of the mission’s instru- ments,” Stevenson said. “And it is only the first of many discoveries that it will make.” Lustig-Yaeger agreed. “With this telescope, rocky exoplanets are the new frontier.” LHS 475 b is relatively close, at only 41 light-years away, in the con- stellation Octans. ! T his illustration, based on observations from Webb, reflects that exoplanet LHS 475 b is rocky and almost precisely the same size as Earth based on new evidence from NASA’s James Webb Space Telescope. The planet is only a few hundred degrees warmer than our home planet. Webb has not captured a direct image of this planet. [NASA, ESA, CSA, Leah Hustak (STScI)] MARCH-APRIL 2023 what is present, they can definitely say what is not present. “There are some terrestrial-type atmospheres that we can rule out,” explained Lustig-Yaeger. “It can’t have a thick methane-dominated atmosphere, similar to that of Saturn’s moon