For the first time, JWST has discovered an exoplanet through direct imaging, revealing TWA 7 b, a Saturn-mass world.
Astronomers using NASA’s James Webb Space Telescope have captured compelling evidence of a planet with a mass similar to Saturn orbiting the young nearby star TWA 7. In this image combining ground-based data from ESO’s Very Large Telescope (VLT) and data from Webb’s MIRI (Mid-Infrared Instrument), light from the star TWA 7 has been subtracted. The location of the star is marked with a circle and a star symbol at the center of the image. The blue color represents data from the VLT’s SPHERE instrument, which showcases the location of the disk surrounding the host star. MIRI data is shown in orange. The bright orange spot to the upper right of the star is the source identified as TWA 7 b, within the debris disk. The more distant orange spot visible in the left of the image is an unrelated background star. Credit: NASA, ESA, CSA, Anne-Marie Lagrange (CNRS, UGA), Mahdi Zamani (ESA/Webb)
The James Webb Space Telescope (JWST) has captured a direct image of a previously unknown exoplanet. This discovery was the direct result of research led by a scientist at the Centre National de la Recherche Scientifique (CNRS) in Paris. The details, published June 25, 2025, in Nature, note that this a first for the telescope and was achieved using a French-produced coronagraph installed on the JWST’s Mid-Infrared Instrument (MIRI).
Tough to photograph
Astronomers study exoplanets, in part, to help us understand how our (and other) solar system formed. As of June 11, there have been 5,921 confirmed discoveries. Most of these planets have been detected indirectly because obtaining images of them is challenging. Seen from Earth, exoplanets are faint and located quite close to the star they orbit. So, their light tends to be overwhelmed by that of their star. But JWST still managed to capture an image of TWA 7 b, the designation given to the new exoplanet.
To overcome this problem, the CNRS developed, in collaboration with the Centre for Extragalactic Astronomy at Durham University in England, a telescopic attachment for MIRI that functions like a coronagraph. It mimics the effect observed during a total solar eclipse. But instead of the Moon blocking the Sun’s light, the coronagraph blocks the light from the star, which makes it easier for the space telescope to observe any objects surrounding it. It is this technique that allowed the team to discover the new exoplanet, located within a disk of rocky debris.
Look at me!
Some systems of planets around distant stars are more promising targets than others. Scientists have focused on ones that are a few millions years old and that they can image from above (because one of their poles points toward Earth). What JWST sees, hopefully, is the star surrounded by a disk of material that will make — or has made — a planet or planets. Because these planets are young, they’re still hot, which makes them brighter than others that formed previously. Helping discovery is that such low-mass planets are easier to detect in middle-infrared wavelengths, for which the JWST was designed to view. Among the disks the JWST detected, two drew special attention from researchers, with previous observations revealing concentric ring-like structures within them.
One of the two systems, the star CE Antliae, but for this study named TWA 7, has three visible rings. One is narrow and is surrounded by two empty areas. The image obtained by the JWST revealed a heat source in this ring. After much study, the scientists concluded that it was most probably an exoplanet. Computer simulations have confirmed the formation of a thin ring and a hole at the planet’s position, which corresponds to the observations made with the JWST.
A lightweight
The new planet is TWA 7 b, where the “b” means that this is the first exoplanet discovered in this system. (The “a,” if used, refers to the star.) One of the striking things about this discovery is that TWA 7 b is 10 times less massive than those previously captured in images. Its mass is comparable to Saturn’s, or 30 percent that of Jupiter.
This discovery shows that the JWST can directly image small exoplanets, which are more similar to the Earth than to Jupiter. And the space telescope may be able to spot even smaller worlds. Researchers hope to capture images of planets with just 10 percent of Jupiter’s mass. This discovery shows that future generations of space-based and ground-based telescopes can, indeed, make significant discoveries of exoplanets, especially with the help of more advanced coronagraphs. The next few decades could see a huge rise in the number of Earth-sized planets orbiting distant stars.
