The search for life beyond Earth is full of surprises, and the James Webb Space Telescope just found new information. Astronomers set their sights on TRAPPIST-1d, an exoplanet once thought to be one of the best bets for finding an Earth-like atmosphere.

Instead, the data revealed a harsher truth: this rocky neighbor doesn’t look much like home after all.

The exoplanet in focus

TRAPPIST-1d lives about 40 light-years away in the constellation Aquarius. It is part of the famous TRAPPIST-1 system, discovered in 2017 when NASA’s now-retired Spitzer Space Telescope and ground-based observatories spotted seven Earth-sized planets circling a small red dwarf star. Until then, no other star had been found with so many rocky worlds orbiting so close.

Of those seven, TRAPPIST-1d was especially intriguing. Similar in size to Earth and sitting on the edge of the so-called “habitable zone,” it seemed possible that liquid water could exist there under the right conditions. That made it a prime target for Webb’s first wave of exoplanet studies.

What Webb just found

Using its powerful Near-Infrared Spectrograph, Webb searched for the chemical fingerprints of gases that define Earth’s air: water vapor, carbon dioxide, and methane. Unfortunately, none appeared. The absence of these molecules rules out an atmosphere similar to Earth’s.

That doesn’t mean the planet is entirely airless. Scientists suggest three options: it could have a very thin atmosphere like Mars, thick and cloudy skies like Venus, or no significant atmosphere at all. Any of these scenarios would make it extremely difficult for the exoplanet to support surface water or life as we know it.

Challenges of living around a red dwarf

Part of the problem lies with the parent star. TRAPPIST-1 is a small red dwarf, cooler and dimmer than our Sun, but far more active. It regularly flares, blasting its planets with high-energy radiation. Such bursts can strip away atmospheres over time, leaving bare, hostile rocks behind.

TRAPPIST-1d, being the third planet from the star, orbits very close — only about 2% of the Earth-Sun distance. That puts it in the line of fire of the star’s outbursts. While this might sound discouraging, astronomers still want to study red dwarfs. These stars are by far the most common in the galaxy, meaning they may host the majority of rocky planets. If any exoplanet can hang on to an atmosphere in such conditions, that would be an important clue in the hunt for habitable worlds.

Similarities to Earth

On paper, TRAPPIST-1d checks several Earth-like boxes. It is nearly the same size, has a rocky surface, and receives a comparable amount of starlight. Its year is a quick one — the planet completes a full orbit in just four Earth days. For a moment, scientists wondered if it might be a true Earth cousin. Webb’s findings show the resemblance ends there.

Why we won’t colonize this exoplanet

Could humans ever live there? Not with what we know today. At 40 light-years away, TRAPPIST-1d is hundreds of trillions of miles from Earth. Even if technology existed to reach it, the lack of a protective atmosphere makes it inhospitable. Radiation from the star would bombard the surface, and without a stable blanket of gases, liquid water would vanish quickly.

The purpose of Webb’s observations is not to scout for new homes for humanity but to understand how different kinds of planets form, evolve, and survive around their stars. Every exoplanet Webb studies gives scientists a clearer sense of which ones deserve closer looks in the future.

The verdict on TRAPPIST-1d is sobering: no Earth-like skies, no easy chance for liquid oceans. But this is still progress. Each negative result narrows the search. As one researcher put it, if a planet can keep an atmosphere in the blast zone of a red dwarf, it could probably survive anywhere.

So while TRAPPIST-1d won’t be our second Earth, it sharpens our understanding of how fragile atmospheres can be. We might not send Matt Damon to grow potatoes up there any time soon (they would wilt before growing spuds), but the JWT will keep on studying this exoplanet!