James Webb Telescope Captures First Direct Image of Saturn-Mass Exoplanet

The James Webb Space Telescope (JWST) has captured its first direct image of a newly discovered exoplanet. Astronomers announced that Webb imaged a Saturn-mass planet orbiting the nearby young star TWA 7. Dubbed TWA 7 b, the planet's mass is only about 0.3 times that of Jupiter – roughly Saturn's mass – making it the smallest planet ever seen via direct imaging. Most of the nearly 6,000 known exoplanets have been detected indirectly. To spot TWA 7 b, the JWST team used a coronagraph (like a solar eclipse) to block the star's light and reveal the faint planet.

Detecting a Hidden World

According to the study published in the journal Nature, Webb's team targeted TWA 7 because its dusty disk is viewed nearly face-on, revealing clear ring structures. They used Webb's MIRI instrument with a coronagraph to mask the star's glare. After processing the data, a faint infrared point source appeared roughly 1.5 arcseconds from TWA 7 (about 50 times the Earth–Sun distance).

This source lies in a gap of the star's second dust ring. Its brightness and color match what theoretical models predict for a young, cold planet roughly Saturn's mass. The object seems to be carving out the ring gap just as an orbiting planet would. Astronomers ruled out other explanations (like a background star) to confirm the signal is best explained by a planet.

A Step Toward Smaller Worlds

TWA 7 b's Saturn-like mass makes it about ten times less massive than any exoplanet previously captured in a direct image. Its discovery shows that Webb can now image worlds far smaller than the giant exoplanets seen before. Scientists say the telescope may eventually detect planets as light as 10% of Jupiter's mass, pushing toward Earth-like size.

This breakthrough “paves the way” to imaging truly terrestrial planets in the future. Astronomers even predict that upcoming observatories could dramatically increase the number of Earth-size planets seen by direct imaging. Next-generation telescopes – on the ground and in space – are being planned with even more powerful coronagraphs to hunt for the first directly photographed Earth analogues.