Astronomers have confirmed Elias 2-24 b as the youngest known exoplanet, a world less than a million years old still embedded in its natal protoplanetary disk. The discovery resolves a decade-old debate over a faint glowing dot in the Ophiuchus star-forming region, challenging current planet-formation models.
Most planets discovered outside our solar system are billions of years old, weathered and settled into clear orbital paths. Finding an infant world buried deep inside the dust and gas from which it formed is exceptionally rare. Researchers working with archival data have now identified a baby planet that shatters previous age records by millions of years, offering a direct look at planetary evolution in real time.
Archival Keck Observations Confirm Elias 2-24 b
The discovery centers on a young star designated Elias 2-24, located roughly 450 light-years from Earth in the Ophiuchus star-forming region. A research team led by Andrea Bernardi, a doctoral candidate at the Universidad Diego Portales in Chile, focused on stellar systems featuring distinct gaps in their surrounding debris disks. Current astrophysical models indicate that growing planets carve out these voids as they gather material from their natal disks. To peer through the thick dust surrounding Elias 2-24, the team re-analyzed archived coronagraph observations from the W. M. Keck Observatory in Hawaii, which is part of a NASA-funded partnership. The 2018 observations utilized the Near Infrared Cam 2 (NIRC2) instrument onboard the Keck telescope.
By blocking out the blinding light of the host star, the coronagraph exposed the faint, reflected light of nearby orbiting objects. Researchers compared positional data collected by Keck in 2018 and 2020 to track the luminous speck over time. They calculated that the statistical probability of an interfering background star causing the observed signal was just 0.015 percent. That motion analysis confirmed the object was not background noise or an instrumental artifact, but a genuine planetary body gravitationally bound to its host star.
Resolving a Decade-Old Debate in the Ophiuchus Star-Forming Region
The confirmation puts to rest a question astronomers have debated for about 10 years. Observations collected by the Atacama Large Millimeter/submillimeter Array in Chile first revealed a prominent gap in the dusty disk surrounding Elias 2-24. Shortly after, the European Southern Observatory’s Very Large Telescope spotted a faint point of light sitting inside that void. While scientists suspected it might be a planet, existing theories suggested a large world should not be able to form so early or so far from its star.
Standard models predict that it takes about 5 million years to form a Jupiter-size planet at Jupiter’s distance from the Sun, and even longer farther out. Yet the newly confirmed world orbits Elias 2-24 at a distance of approximately 55 astronomical units—well beyond Pluto’s orbit in our solar system—and sits precisely in the middle of a 30-astronomical-unit-wide gap. Evaluated mass values span 1.0 to 4.0 times that of Jupiter, alongside anticipated surface temperatures between 1,300 and 1,600 Kelvin, rendering the body unusually hot given its immense distance from the parent star.
Challenging Planet-Formation Models With Previous Record Holders
Until this discovery, the youngest confirmed exoplanets were part of a four-way tie between two planets orbiting the star PDS 70 and two planets orbiting WISPIT 2. All of those previously recorded systems are more than 5 million years old. Because Elias 2-24 b is less than a million years old, it eclipses those benchmarks by a significant margin.
Our planet-formation models already struggled to explain the previous record holders for the youngest known planet — a four-way tie between two planets orbiting the star PDS 70 and two planets orbiting the star WISPIT 2 — which are all more than 5 million years old.
Lucas Cieza, professor at the Instituto de Estudios Astrofísicos
Cieza noted that Elias 2-24 b shows us that current theoretical frameworks are still missing crucial developmental processes. While the galaxy churns out stars and planets continuously, a large gap remains in what most telescopes can detect, leaving researchers largely blind to planetary nurseries.
Next Steps for Tracking the Orbit of Elias 2-24 b
Due to the planet lying roughly 54.9 astronomical units away from its parent star, it traversed only about 1.5 degrees across its complete 360-degree orbit throughout the initial 2018 to 2020 monitoring period.
Measuring its exact orbit will allow astronomers to gain insight into the earliest stages of planetary development. Researchers also note that upcoming instruments, such as NASA’s Roman, will make detecting similar baby planets significantly easier in the years ahead.