James Webb telescope captures its first direct image of a glowing exoplanet the size of Saturn

Daily Mail​

26-06-2025

It's provided us with stunning pictures of distant galaxies, nebulae and dying stars.
But now, for the first time ever, the James Webb Space Telescope (JWST) has captured an unprecedented image of an exoplanet outside our solar system.
The planet, dubbed TWA 7b, was found orbiting a young red dwarf star about 111 light-years from Earth.
Scientists estimate the celestial body is roughly the same mass as that of Saturn, or 100 times larger than Earth.
That makes TWA 7b the smallest exoplanet ever directly observed - 10 times less massive than previous discoveries.
Although the JWST has discovered hundreds of exoplanets, these have all been found indirectly by carefully watching the host star.
However, by simulating the effects of an eclipse, scientists were able to filter out the excess starlight and spot the exoplanet's faint infrared glow.
Lead researcher Dr Anne-Marie Lagrange, an astrophysicist at the Paris Observatory, told MailOnline: 'Detecting exoplanets is not easy in general. Imaging them is even more challenging. This is why the lightest planets imaged before TWA 7b [were] massive giants, a few times Jupiter's mass.'
This image combines ground-based data from the Very Large Telescope (VLT) and data from the JWST. The star has been hidden and marked with a white star symbol. The blue region shows the debris field spotted by the VLT and the orange circle is the exoplanet as seen by the JWST
Exoplanets, any planet outside the solar system, are small and appear to be extremely close to their star when seen from Earth.
Since they don't give off much light of their own, this makes them extremely hard to see against the bright background.
Scientists normally find exoplanets using the 'transit method', which involves watching the planet pass in front of its parent star and measuring how much the light dims.
However, 20 years ago Dr Lagrange and her colleagues developed a technique using a device called a 'coronagraph' to block out the light of distant stars.
This allowed her to see the rings of material floating around distant stars for the very first time.
Dr Lagrange and her colleagues decided to focus on stars that they could see from the 'top-down', looking down on the star's pole to give a bird's eye view of the planetary system.
They also chose to look for young stars since these have rings of material which are still glowing with heat, making them easier to spot.
Astronomers already knew that the 6.4-million-year-old TWA 7 star had three distinct rings of debris which could be seen from the top down - making it an ideal target for the JWST.
Using the coronagraph mounted on the space telescope the researchers blocked out the light from the star and then removed any residual glow using image processing.
This revealed a faint source of infrared radiation within TWA 7's debris field, about 50 times farther from the star than Earth is to the Sun.
This source was located in a 'hole' within one particularly narrow dust ring.
That told Dr Lagrange that she was likely looking at a young planet which was just starting to affect debris in its orbital path.
Although there is a very slim possibility that this signal could be a galaxy far in the background, initial analysis suggests it is likely to be a young, cold planet with a temperature of 47°C (120°F).
Dr Lagrange says: 'Clearly it formed in a disk a few million years ago. It has gravitational interactions with the debris disk.'
Dr Lagrange also says that a thin ring of material forming around the planet's orbit, known as a Trojan Ring, was predicted by models but had never been observed before.
This discovery is exciting because it is the first time an exoplanet the size of the planets in our solar system has been directly observed.
This is the smallest exoplanet ever directly observed but the JWST (pictured) has the potential to image planets just 10 per cent of Jupiter's mass
Exoplanets Dr Lagrange has directly observed using Earth-based telescopes are giants, many times the mass of Jupiter.
But the JWST has the potential to spot exoplanets just a tenth of Jupiter's mass.
Scientists could use these observations to help uncover the mysteries of how our own solar system formed.
However, Dr Lagrange says they cannot yet directly observe 'Earth-like planets in the habitable zone'.
That means the hunt for life beyond our solar system will still need to wait for even more powerful telescopes such as NASA's proposed Habitable Worlds Observatory.
Scientists study the atmosphere of distant exoplanets using enormous space satellites like Hubble
Distant stars and their orbiting planets often have conditions unlike anything we see in our atmosphere.
To understand these new world's, and what they are made of, scientists need to be able to detect what their atmospheres consist of.
They often do this by using a telescope similar to Nasa's Hubble Telescope.
These enormous satellites scan the sky and lock on to exoplanets that Nasa think may be of interest.
Here, the sensors on board perform different forms of analysis.
One of the most important and useful is called absorption spectroscopy.
This form of analysis measures the light that is coming out of a planet's atmosphere.
Every gas absorbs a slightly different wavelength of light, and when this happens a black line appears on a complete spectrum.
These lines correspond to a very specific molecule, which indicates it's presence on the planet.
They are often called Fraunhofer lines after the German astronomer and physicist that first discovered them in 1814.
By combining all the different wavelengths of lights, scientists can determine all the chemicals that make up the atmosphere of a planet.
The key is that what is missing, provides the clues to find out what is present.
It is vitally important that this is done by space telescopes, as the atmosphere of Earth would then interfere.
Absorption from chemicals in our atmosphere would skew the sample, which is why it is important to study the light before it has had chance to reach Earth.
This is often used to look for helium, sodium and even oxygen in alien atmospheres.