TL;DR: Astronomers confirmed a Jupiter-mass world under 1 million years old still growing inside its birth disk.

Astronomers have confirmed the youngest known planet, a Jupiter-mass world still embedded in its natal disk of dust and gas less than 1 million years after its star began to form. Called Elias 2-24 b, the object was identified by reanalyzing old infrared images and tracking its motion over time, according to NASA Science.

The result was reported Sept. 16, 2026, in a study led by doctoral candidate Andrea Bernardi of Universidad Diego Portales in Chile and published in The Astrophysical Journal Letters, according to NASA Science and the W. M. Keck Observatory. The work combined observations from the W. M. Keck Observatory in Hawaii, the Atacama Large Millimeter/submillimeter Array in Chile, and the European Southern Observatory's Very Large Telescope in Chile.

The planet circles the young star Elias 2-24, located about 450 light-years from Earth, and sits inside a prominent gap in the surrounding disk while material continues to fall onto it, according to NASA Science. That placement provides unusually direct evidence that young giant planets carve the gaps seen in planet-forming disks and offers a nearby example of the rapid gas-accumulation phase predicted by the core accretion model, according to the W. M. Keck Observatory.

A record five times younger than prior holders

The previous age record was shared by four older worlds, two orbiting the star PDS 70 and two orbiting the star WISPIT 2, all more than 5 million years old, according to NASA Science. Elias 2-24 b, with an age of less than 1 million years, is therefore younger by a factor of more than five.

That age difference matters because current formation theories already had difficulty accounting for giant planets at 5 million years, according to NASA Science. Co-author Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos in Chile, said planet-formation models struggled to explain the prior record holders and that the new object shows the models are still missing important processes.

The confirmation establishes Elias 2-24 b as the youngest exoplanet discovered to date, a term that means a planet outside the solar system, according to NASA Science and the paper abstract. The abstract gives the age as no more than about 1 million years and says the confirmation carries important implications for formation timescales and the origin of gaps in very young disks.

The mass estimate also points to a true giant. NASA Science describes Elias 2-24 b as about as massive as Jupiter, while the study abstract infers 1.9 to 4.0 Jupiter masses by comparing the measured brightness with 1-million-year brightness models, without including accretion effects. The authors report that the range agrees with estimates based on the properties of the gap and planet-disk interactions.

Where the planet sits

The measured position places the planet well away from its star and squarely in cleared material. The paper reports a separation of 394 ± 31 milliarcseconds, equivalent to 54.9 ± 4.3 astronomical units, at a position angle of 298.8 ± 3.2 degrees, inside the narrow gap of the protoplanetary disk.

NASA Science expresses the same distance in simpler terms, reporting that the glowing point was 55 times farther from its star than Earth is from the Sun. By comparison, present models predict that building a Jupiter-size planet at Jupiter's distance — just over five times the Earth-Sun distance — takes about 5 million years, with still longer times farther out.

The host environments in the survey were selected because they appeared likely to be forming planets. The team examined seven stars observed with the coronagraph at Keck, each hosting a dust- and gas-rich disk containing dust, gas and chunks of ice and rock, with structures and gaps suggesting planets could be forming, according to NASA Science. The abstract likewise describes all seven targets as hosting protoplanetary disks with substructures such as gaps and cavities potentially tracing ongoing formation.

With the coronagraph blocking light from the host stars, the astronomers searched for fainter embedded objects in those dusty disks, according to NASA Science. Bernardi said the team expected planets to lie within gaps because the planets carve those gaps, and reported that Elias 2-24 b was found in exactly such a location.

A decade-long puzzle closed by archive data

The confirmation resolves a question that had lingered for about a decade, according to NASA Science. About ten years ago, ALMA showed a gap in the dusty disk around the young star, and the Very Large Telescope later detected a faint point of light sitting in that gap. Astronomers debated whether the point was a planet because formation theories suggested gaps should appear too early and too far from their stars for planets to have formed there.

The Keck portion of the solution began with observations taken in 2018, according to the W. M. Keck Observatory. That year, Alice Zurlo, then studying young stars with structured disks, observed Elias 2-24 with Keck's Near Infrared Camera 2, known as NIRC2. The data showed a faint signal, but the evidence was insufficient to identify it as a planet.

Bernardi later returned to the same data through the Keck Observatory Archive, a NASA-funded partnership between Keck Observatory and the NASA Exoplanet Science Institute at Caltech/IPAC, according to NASA Science and the W. M. Keck Observatory. The archive preserves Keck observations and makes them available for later research long after they were obtained.

Reanalysis with newer processing methods recovered a signal consistent with a forming planet, according to the W. M. Keck Observatory. Additional archival Keck observations from 2020, together with independent Very Large Telescope observations and supporting ALMA evidence, helped confirm the object. By stitching the observations together and analyzing motion over time, the team found that the point behaved more like a planet than an imaging defect or background star, according to NASA Science.

The underlying Keck survey used high-contrast imaging with the Keck/NIRC2 vortex coronagraph in the L-prime and M-s bands, with observations obtained between May and June 2018, according to the study abstract. The team reduced the data with a custom pipeline based on the VIP Python package and produced processed images using angular differential imaging and reference differential imaging combined with principal component analysis. It then derived five-sigma contrast curves and detection limits for all targets, reaching sensitivities of 1 to 11 Jupiter masses at separations beyond about 0.25 arcseconds.

Why baby planets are rarely seen

Dust is the central obstacle. Stars are born in swirling clouds of gas and dust, and planets assemble from leftover material that clumps together and gradually clears a path around the star, according to NASA Science. The same shroud that supplies planet-building material makes the newborn stage difficult to observe.

The detection method used for most known worlds adds to the bias. Most of the exoplanets discovered so far were found through transits, which occur when a planet passes in front of its star and temporarily reduces the light received on Earth, according to NASA Science. Those dips are hard to detect when planets remain deeply buried in dust or orbit far from their stars.

As a result, the overwhelming majority of the 6,000 currently confirmed exoplanets are billions of years old and lie very close to their stars, according to NASA Science. Current planet-formation models therefore combine complex theories and simulations with observations of young disk-bearing stars where planets cannot yet be detected, making confirmed infants such as Elias 2-24 b important tests.

Cieza said the galaxy continuously produces new stars and planets at every evolutionary stage, so the full sequence should exist in principle, but added that telescopes remain largely blind to the infant-planet interval, according to NASA Science. Finding and studying more objects like Elias 2-24 b would help refine those models.

Direct support for gap carving and rapid gas growth

The discovery provides one of the clearest examples yet of a planet occupying a disk gap, according to the W. M. Keck Observatory. While ALMA had previously revealed rings and dark gaps in many disks, and many astronomers suspected emerging planets were responsible, direct evidence had remained limited.

Bernardi said the team can now link gaps in protoplanetary disks to embedded planets with much greater confidence, calling the result direct evidence that planets forming in a disk can produce those structures, according to the W. M. Keck Observatory. NASA Science likewise describes material from the disk as actively accreting onto the Jupiter-mass planet inside a prominent gap, supporting the leading giant-planet formation theory.

That theory is core accretion, described by the W. M. Keck Observatory as the leading account of giant-planet formation. Under the team's analysis, Elias 2-24 b is in a brief but critical phase in which it rapidly accumulates gas from the surrounding disk and builds its atmosphere.

Zurlo, a professor at Universidad Diego Portales and a study author who conducted initial work on the system in 2018, said the planet is undergoing an evolutionary stage for which theoretical models still struggle to predict mass, entropy and expected luminosity reliably, according to the W. M. Keck Observatory. She said better constraints on its dynamical mass should help refine and recalibrate evolutionary models for young planets.

Cieza described the system as a much younger version of a planetary system like Earth's own, noting that the solar system is billions of years old and must be reconstructed indirectly, while Elias 2-24 b can be studied while formation is still underway, according to the W. M. Keck Observatory. NASA Science similarly describes the system as a time machine for exploring what Earth's planetary system may have resembled billions of years ago.

What U.S. researchers and telescopes gain

The U.S. contribution centers on Hawaii and California archives and analysis. Keck Observatory on Maunakea partners with NASA under a cooperative agreement, and the Keck Observatory Archive is a NASA-funded partnership with the NASA Exoplanet Science Institute at Caltech/IPAC, according to NASA Science. The study also included co-authors from the California Institute of Technology, according to the paper abstract.

Keck Chief Scientist John O'Meara said the result illustrates the long scientific life of astronomical data, with years-old observations yielding a discovery after new techniques, improved models and a fresh examination were applied, according to the W. M. Keck Observatory. He said the archive lets scientists revisit earlier observations and ask new questions that were not possible when the data were collected.

The team continues to study the planet and hopes to obtain spectroscopy and other measurements that could reveal more about its atmosphere, temperature, mass and ongoing accretion, according to the W. M. Keck Observatory. For now, the authors present Elias 2-24 b as a rare opportunity to watch a giant planet while it is still assembling, with each new observation adding detail to the origin of planetary systems.

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