Youngest Exoplanet Discovered – A Giant That Shouldn’t Exist Yet

For years astronomers have been peering at the swirling disk of gas and dust surrounding a young star called Elias 2‑24, about 450 light‑years away, wondering if something was hiding in the shadows. The first hint came from ALMA in Chile, which revealed a dark gap in the disk—a classic sign that a planet might be carving a path.

Later, the European Southern Observatory caught a faint speck of light nestled in that very gap. At first it looked like a stray artifact, but the idea that a newborn planet could already be glowing was hard to ignore.

What made the case even stranger was the age. According to the textbook picture, a Jupiter‑mass planet sitting at a distance eleven times farther than Earth’s Sun‑Jupiter spacing needs roughly five million years to amass enough material. Yet Elias 2‑24 itself is thought to be only a few hundred thousand years old, maybe as young as 200,000 years. How could such a hefty world appear so quickly?

In a paper released this week in The Astrophysical Journal Letters, a team led by Chilean doctoral student Andrea Bernardi confirmed the source of the glimmer: a bona fide planet, now dubbed Elias 2‑24 b. By stitching together Keck Observatory coronagraph images taken between 2018 and 2020, they traced the object’s motion and found it behaved exactly like a planet orbiting its star, not like a background star or imaging glitch.

Because the host star is still in the throes of formation—its accretion rate is unusually high—the researchers argue the planet must be similarly youthful. They adopt a conservative age of one million years for the calculations, which suggests Elias 2‑24 b could be anywhere from two to fourteen times the size of Jupiter. The exact mass remains fuzzy, cloaked as it is in a thick shroud of gas and dust.

“Our models already struggled with the previous record‑holders—four planets orbiting PDS 70 and WISPIT 2 that are over five million years old,” said co‑author Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos. “Elias 2‑24 b shows we’re still missing key ingredients in how giants form so fast and so far out.”

The discovery is a reminder of how much we still rely on teamwork across telescopes. “It’s not just one instrument; it’s the synergy of ALMA, the VLT, Keck, and soon the Roman Space Telescope,” Bernardi added. The Roman mission, which just saw first light, carries the most powerful coronagraph ever flown in space, capable of spotting planets a hundred million times fainter than their host stars. That kind of sensitivity could turn a handful of rare finds into a steady stream.

For now, Elias 2‑24 b is a priceless laboratory. Watching a planet in the act of growing—still embedded in its birth disk—offers a direct test for theories that have, until now, been forced to rely on indirect clues. As Cieza puts it, “We finally have a glimpse of planet formation in real time, and the Roman telescope will let us find many more of these infant worlds.”