Astronomers Confirm Elias 2-24 b as the Youngest Known Exoplanet Ever Detected

Astronomers have confirmed a planet less than one million years old, a Jupiter-mass world named Elias 2-24 b that is still embedded in the disk of gas and dust where it formed. The result, published September 16, 2026 in The Astrophysical Journal Letters, makes Elias 2-24 b the youngest confirmed exoplanet ever detected and resolves a debate that began roughly a decade ago over a mysterious gap in the star's protoplanetary disk. The study was led by Andrea Bernardi, a doctoral candidate at the Universidad Diego Portales in Chile, and it draws on archival observations from the W. M. Keck Observatory in Hawaii together with earlier data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the European Southern Observatory's Very Large Telescope (VLT).

The host star, Elias 2-24, sits about 450 light-years from Earth. The planet orbiting it is roughly as massive as Jupiter, and it is still actively gathering material from the surrounding disk. That ongoing accretion is what allowed astronomers to detect it: the planet is a faint point of light carving a gap in the dusty disk, exactly where theory says a forming world should be. "The planets should be found within the gaps, since they are carving them," Bernardi said. "And that's exactly where we found Elias 2-24 b."

Most of the roughly 6,000 exoplanets confirmed so far are billions of years old and orbit relatively close to their stars, which makes them relatively easy to study. Baby planets, by contrast, are rare, faint and usually hidden inside the bright glow of their natal disks. Elias 2-24 b offers a rare direct look at a stage of planet formation that telescopes have mostly missed.

The decade-old debate centered on a gap that ALMA spotted in the disk around Elias 2-24. The VLT then detected a faint point of light inside that gap. The question was whether the glow was a planet or something else, a background star or an artifact, because current models predict it takes about 5 million years to form a Jupiter-size planet at Jupiter's distance from the Sun, and even longer farther out. The candidate object sits about 55 times farther from its star than Earth is from the Sun, an extreme location that made a young age hard to accept.

Key Facts

NASA Science reported on September 16 that the confirmation used data from NASA-funded archives and that Elias 2-24 b is still whirling in its natal disk of dust and gas. The study appears in The Astrophysical Journal Letters and carries the DOI 10.3847/2041-8213/ae9bb6. Bernardi's team homed in on archival observations of seven stars that had been observed with the coronagraph at the W. M. Keck Observatory, which blocks the light of the host star so that fainter planets can be seen.

Phys.org reported on September 16 that the planet is about as massive as Jupiter and that its star is about 450 light-years from Earth. The same report noted that the planet orbits about 55 times farther from its star than Earth does from the Sun. The previous record holders for the youngest known planet were a four-way tie: two planets orbiting the star PDS 70 and two planets orbiting the star WISPIT 2, all more than 5 million years old.

ScienceDaily reported on September 17 that the researchers examined archived observations of seven young stars and that the team found the same object in 2018 and 2020 Keck observations, tracked its motion over time, and confirmed it is a planet rather than an artifact or a background star. The confirmation therefore rests on data from the Keck Observatory Archive, a NASA-funded partnership between Keck Observatory and the NASA Exoplanet Science Institute (NExScI) at Caltech/IPAC.

Astrobiology.com reported on September 17 that the study combines observations from the W. M. Keck Observatory, ALMA and the ESO Very Large Telescope, and that the findings support the core accretion model of giant planet formation. The discovery began with observations conducted at Keck Observatory in 2018, when Alice Zurlo, then part of the research team studying young stars with structured protoplanetary disks, observed Elias 2-24 with Keck's Near Infrared Camera 2 (NIRC2).

Keck Observatory Chief Scientist John O'Meara said that astronomical data can have a remarkably long shelf life, and that the observations existed for years before new techniques, improved models and a fresh look revealed something extraordinary. Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos in Chile and a co-author, said that planet-formation models already struggled to explain the previous record holders, which are all more than 5 million years old.

Analysis

What this really means is that the standard timeline for building a giant planet is too slow, too rigid, or both. The core accretion model, which builds a gas giant by assembling a rocky or icy core and then wrapping it in gas, predicts that a Jupiter-size planet at Jupiter's distance from the Sun needs about 5 million years. Elias 2-24 b is less than 1 million years old and sits roughly 55 times farther out than Earth, where the disk is thinner and orbital clocks tick more slowly. If the planet is really that young and really that far out, then some faster channel of formation, perhaps a gravitational instability in the disk or a head start from a massive seed, must be at work.

The bigger picture here is that the debate over the gap around Elias 2-24 was never only about one star. It was a test of whether the bright gaps that ALMA sees in protoplanetary disks are truly carved by planets. The new confirmation links a disk gap to a planet directly, using the same object observed by three different facilities. That strengthens a central prediction of planet-formation theory and gives astronomers a template for interpreting the thousands of disk gaps that ALMA and other observatories have catalogued.

The result also shows the value of archives. The 2018 and 2020 Keck observations were not taken to find this planet. They were taken for a broader survey of young stars with structured disks. Only new data-processing techniques, applied years later, pulled the faint signal out of the noise. Cieza said that the object sits right at the limit of what current technology can detect, and that it was the combination of observations from multiple observatories that allowed the team to show the planet is really there.

There is also a cautionary note. Elias 2-24 b is one object, and its properties are extreme. The team has not yet measured its atmosphere, temperature or accretion rate in detail. Until spectroscopy confirms those details, the planet's exact formation pathway remains open. But the age and the mass are enough to force a revision of how quickly giant planets can appear, especially in the cold outer reaches of a disk.

Why It Matters

The confirmation resets a record that had stood for years. The youngest known planet is now less than a million years old, compared with the previous four-way tie of PDS 70 b and c and WISPIT 2 b and c, all more than 5 million years old. That is a jump of more than a factor of five in youth, and it pushes observations into the first few hundred thousand years of a planetary system's life, when planets are still assembling.

It also matters for the search for life and for planetary systems like our own. Giant planets shape the architecture of their systems, clearing gaps, scattering smaller bodies and influencing where rocky worlds can form and keep their water. Understanding how fast a Jupiter can form, and how far out it can form, informs how common systems like ours might be.

For observatories, the result is a proof of concept. NASA-funded archives, the Keck Observatory Archive and the NExScI partnership made the confirmation possible without a single new night of telescope time. Bernardi said that Elias 2-24 b is at the limit of what current telescopes can detect, but that with new instruments like NASA's Nancy Grace Roman Space Telescope, such detections should become easier. Roman launched August 30 and carries an even more advanced coronagraph.

Next Up

The team hopes spectroscopy will reveal more about the planet's atmosphere, temperature, mass and ongoing accretion. Those measurements would test whether Elias 2-24 b is a true gas giant formed by core accretion or an object that grew through a different, faster route. Astronomers also expect the Roman Space Telescope's coronagraph to find more young planets in disks, turning a single record-breaking detection into a population that can be compared with models.

Meanwhile, the result is likely to send theorists back to their simulations. If a Jupiter-mass world can exist at less than one million years and at 55 times Earth's distance from its star, then the clock for giant planet formation starts earlier than many models assumed.