James Webb discovers his first exoplanet: it is the size of Earth

The James Webb Space Telescope made the first discovery of an exoplanet on its mission. This star has 99% of the diameter of the Earth.


The James Webb Space Telescope discovered its first exoplanet with proportions very similar to Earth.

The planet, registered as LHS 475 b , is 99% the diameter of Earth and orbits within its star’s habitable zone.

a star to look at

This exoplanet is relatively close to ours: just 41 light-years away in the constellation Octans.

The image of LHS 475 b was obtained thanks to the near infrared spectrograph (NIRSpec) that is in the telescope and was detected thanks to the observations of the transit: monitoring the brightness of the star.

At the moment, it is not yet possible to detail the atmosphere of the exoplanet , but James Webb will carry out more detailed measurements in order to obtain this information.

“These first observational results for a rocky, Earth-sized planet open the door to many future possibilities for studying the atmospheres of rocky planets with James Webb,” said Mark Clampin, director of NASA’s division of astrophysics. “Webb is bringing us ever closer to a new understanding of Earth-like worlds outside the Solar System, and the mission has only just begun.”

To date, only this exoplanet is known to be hundreds of degrees hotter than Earth.

James Webb will continue to study it during the first half of 2023. This is already a great milestone because the telescope, to date, only investigated exoplanets already known to scientists.