Scientists have verified that a giant planet is growing inside the ring of material surrounding a youthful star, and at under a million years old, it ranks as the earliest alien world ever detected.
A world named Elias 2-24 b circles a freshly born star roughly 450 light-years away from our own planet. Its mass falls within a range from two to four times that of Jupiter, and it occupies an orbit nearly twice the distance from its star that Neptune sits from the sun. Researchers revealed the find in The Astrophysical Journal Letters on Sept. 16.
The Gap That Gave It Away
Scientists first detected evidence of the planet in 2017, after they observed a narrow gap in the star’s protoplanetary disk — the swirling ring of gas, dust and other stellar debris left over from the star”s surrounding disk. That gap strongly indicated that an exoplanet had formed there, created when sufficient of the disk’s swirling material had gathered together under gravity, the usual way planets come into being.
But the alien world was not directly visible at the time.
Three Telescopes, One Baby Planet
The new research draws on data from three observatories, which were trained on the same region of sky to examine the gap more closely. The W. M. Keck Observatory sits in Hawaii, while the Atacama Large Millimeter/submillimeter Array is located in Chile. The European Southern Observatory’s Very Large Telescope, also in Chile, made up the third instrument used in the study.
The researchers imaged Elias 2-24 b directly, confirming its existence, and determined its age as well. The planet is probably younger than 1 million years.
What Makes It Remarkable
“What makes Elias 2-24 b so remarkable is its age,” study first author Andrea Bernardi, a doctoral student with the Institute of Astrophysical Studies (IEA) at Diego Portales University in Chile, said in a statement. “This is the youngest planet detected so far, and because it is still actively accreting material from its surroundings, we’re able to observe a stage of planet formation that is rarely seen directly.”
The newly confirmed exoplanet is roughly 5,000 times younger than Earth. It is around 0.008% the age of the oldest known exoplanet, PSR B1620-26 b, or “Methuselah,” which formed around 1.1 billion years after the Big Bang. Compared to the average human lifespan, this makes Elias 2-24 b roughly equivalent to a two- or three-day-old baby.
Breaking the Age Barrier
Astronomers have previously found young exoplanets, though there was a point in their development after which they could no longer be detected by our instruments.
The oldest known exoplanets, including several planets circling the star PDS 70, were roughly 5 million years old for a long while. Telescopes could not detect exoplanets until the gaps in their stars’ protoplanetary disks grew wide enough.
Data analysis and telescope design have now surpassed the old age limits. Astronomers found TIDYE-1b in 2024, a planet thought to be roughly 3 million years old. Scientists then spotted AB Aurigae b in 2025, a world that might date back as little as 2 million years.
The planet Elias 2-24 b is at least twice as young as any known exoplanet, which represents a notable advance.
The Transit Method’s Blind Spot
A majority of the more than 6,000 exoplanets discovered so far have been spotted via the transit method, where a distant world passes between its home star and Earth, causing a temporary dip in the star’s brightness. But this doesn’t work if the alien worlds lurk within a protoplanetary disk, because the swirling debris cloud permanently dims the star’s light when viewed side-on.
That has created a bias toward finding older exoplanets.
A young exoplanet can be detected only when a star’s protoplanetary disk sits at right angles to Earth. That arrangement lets observers look straight down upon it, revealing any openings inside the disk. The difficulty comes from the star’s own light, which frequently overwhelms the fainter glow of the disk itself.
A New Era of Discovery
The Nancy Grace Roman Space Telescope, launched into orbit Aug. 30, could alter that situation. The observatory is now calibrating its instruments and will begin its decades-long mission to study the universe once those tests are complete.
A sophisticated starshade, or coronagraph, fitted to the space telescope works by blocking the light from far-off stars, allowing researchers to examine what lies around them. Specialists expect that Roman might detect as many as 100,000 fresh exoplanets over its mission, and because it has less prejudice toward older worlds, we ought to discover a great many more infant planets.
What the Models Miss
The discovery raises questions about what planet-formation models have missed.
“Our planet-formation models already struggled to explain the previous record holders for the youngest known planet,” Cieza said. “Elias 2-24 b shows us that even our best planet-formation models are still missing some important processes.”
Key Facts
- Elias 2-24 b is less than 1 million years old
- It orbits a newly formed star about 450 light-years from Earth
- It is two to four times as massive as Jupiter
- It sits almost twice as far from its star as Neptune is from the sun
- It is roughly 5,000 times younger than Earth
- It is 0.008% the age of the oldest known exoplanet, PSR B1620-26 b
This work was carried out by a team led by Andrea Bernardi, alongside Andrea Zurlo, Lucas Cieza, Gillian Ruane, Vincent Christiaens, Abhishek Dasgupta and Violette Guidi.
That the cosmos holds unseen phenomena is a constant reminder, and the arrival of instruments such as Roman means the odds of finding them keep growing.
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