NASA's Webb Space Telescope has discovered its first Earth-like exoplanet.

 For the first time, researchers used NASA's James Webb Space Telescope to confirm the existence of an exoplanet, a planet that orbits another star.


The planet, officially known as LHS 475 b, is almost exactly the same size as our own, measuring 99 percent of Earth's diameter.

LHS 475 b is located in the constellation Octans and is only 41 light-years away.

"These first observations from an Earth-size, rocky planet open the door to many future possibilities for studying rocky planet atmospheres with Webb," said Mark Clampin, director of NASA Headquarters in Washington, DC.

"Webb is bringing us closer and closer to a new understanding of Earth-like worlds outside our solar system, and the mission is just getting started," he said late Wednesday in a statement.

Kevin Stevenson and Jacob Lustig-Yaeger of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, led the research team.

Only the Webb Space Telescope is capable of characterising the atmospheres of Earth-sized exoplanets.

Although the team cannot determine what is present, they can state what is not present.

"We can rule out some terrestrial-type atmospheres," Lustig-Yaeger said. "It cannot have a thick methane-dominated atmosphere like Saturn's moon Titan. a

Webb also discovered that the planet is several hundred degrees hotter than Earth.

If clouds are found, researchers may conclude that the planet is more like Venus, which has a carbon dioxide atmosphere and is constantly shrouded in thick clouds.

"We're at the cutting edge of studying small, rocky exoplanets," Lustig-Yaeger explained.