The Webb telescope captures rare planetary seedlings

In a cosmic discovery that underscores just how little we still know about the birth of planetary systems, NASA’s James Webb Space Telescope has directly imaged two infant gas giant planets orbiting a young, sun-like star — and remarkably, they’re at very different stages of development.

The finding, published this week in Nature, showcases Webb’s unparalleled ability to peer deep into the early moments of planet formation, offering an unprecedented view into a process astronomers have long sought to decode.

Two Infant Giants, Light-Years Away

The planetary system in question lies around 310 light-years from Earth in the direction of the southern constellation Musca. Here, a young star named YSES-1, just 16 million years old — practically a newborn by cosmic standards — plays host to these two massive worlds.

Both planets are significantly larger than Jupiter, the largest planet in our solar system. Yet despite orbiting the same star, they appear to be developing in distinctly different ways, challenging long-held assumptions about how planets form.

One Planet Wrapped in Dust, Another in Clouds

The innermost planet, located about 160 times farther from its star than Earth is from the Sun, is a true heavyweight at 14 times Jupiter’s mass. Surrounding it is a disk of fine dust, a feature typical of very young planets still gathering mass or possibly reshaping after a colossal collision. Webb’s sensitive instruments also detected water vapor and carbon monoxide in its atmosphere — an intriguing hint at the building blocks of future moons or even prebiotic chemistry.

The outer planet, twice as distant at 320 Earth-Sun distances, is a slightly lighter behemoth at six times Jupiter’s mass. Unlike its sibling, this planet shows no disk but is instead enveloped by an atmosphere dense with silicate clouds — essentially vaporized rock particles. Webb also identified a mix of methane, water, carbon monoxide, and carbon dioxide swirling in its skies.

A Puzzle for Planet Formation Theories

What makes this discovery particularly puzzling is that these two planets, born from the same protoplanetary disk, seem to be evolving on very different timelines. According to Kielan Hoch, the study’s lead author and an astrophysicist at the Space Telescope Science Institute in Baltimore, planets are generally believed to form within roughly a million years — meaning they should theoretically be at similar stages.

“The big mystery here is how two planets orbiting the same star could look so different so early,” Hoch explained. “One still surrounded by leftover material, while the other has fully developed silicate clouds in its atmosphere. This challenges our assumptions about whether all giant planets are supposed to form and evolve in the same way, especially when born from the same disk.”

Adding to the intrigue, both planets orbit at distances much greater than standard models predict. Most planetary formation theories suggest gas giants form closer to their host star within the dense, dusty protoplanetary disk before migrating outward.

Webb’s Exoplanet Revolution

Since becoming operational in 2022, the James Webb Space Telescope has transformed our understanding of the universe’s infancy — from ancient galaxies to the chemistry of distant worlds. Its observations at near- and mid-infrared wavelengths are especially valuable for studying exoplanet atmospheres, revealing complex physics and chemical interactions previously undetectable.

“Webb is giving us an entirely new window into the atmospheric processes of exoplanets,” Hoch added. “It’s already challenged nearly every atmospheric model we built before it launched.”

A Broader Perspective: A Universe of Surprises

To date, astronomers have confirmed over 5,900 exoplanets beyond our solar system. Yet, less than 2% have been directly imaged — making discoveries like this exceedingly rare. Spotting planets still in their formative years is even more unusual, offering precious clues about the chaotic processes that might have shaped our own solar system billions of years ago.