Elias 2-24 b, a massive exoplanet less than one million years old and still embedded within its natal protoplanetary disk, has been confirmed as the youngest planet ever discovered, offering astronomers an unprecedented direct look at planetary evolution in real time.
Detecting an Infant World Inside a Dusty Disk
Finding young planets is notoriously difficult because stellar nurseries are thick with gas and dust. While scientists have confirmed approximately 6,000 exoplanets to date, the vast majority of them are billions of years old. Older planets are much easier to detect using the transit method, which registers the slight dimming of a star’s light as a planet passes in front of it. Newly formed celestial bodies, however, remain buried inside their surrounding protoplanetary disks.
To bypass this obstacle, a research team led by Andrea Bernardi, a doctoral candidate at Diego Portales University in Chile, focused on stellar systems featuring distinct gaps in their dense surrounding matter. Current astrophysical models dictate that growing planets carve out these voids as they gather material. As detailed in The Astrophysical Journal Letters, the team reanalyzed archival coronagraph data from the W. M. Keck Observatory in Hawaii. By blocking out the blinding light of the central star, the coronagraph exposed the faint, reflected light of nearby orbiting objects.
The discovery resolves a decade-old debate surrounding the star Elias 2-24, located roughly 450 light-years from Earth in the Ophiuchus star-forming region. Earlier observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile revealed a prominent gap in the dusty disk, while the European Southern Observatory’s Very Large Telescope spotted a faint point of light within that void. By comparing positional data collected by Keck in 2018 and 2020, researchers confirmed that the bright spot was not background noise or an unrelated star, but a genuine planetary body gravitationally bound to its host star.
Challenging Current Planet-Formation Models
The newly confirmed exoplanet orbits Elias 2-24 at a distance of approximately 55 astronomical units—well beyond the orbit of Pluto in our own solar system. Calculations place its mass between 1.0 and 4.0 times that of Jupiter, though its volume is expected to be much smaller than our local gas giant. Standard evolutionary models calculate the object's temperature between 1,300 and 1,600 Kelvin, making it surprisingly hot given its vast distance from the host star.
Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos in Chile and co-author of the study, noted that previous record holders for youth were a four-way tie between planets orbiting the stars PDS 70 and WISPIT 2. Those systems are all more than five million years old. “Our planet-formation models already struggled to explain the previous record holders for the youngest known planet,” Cieza stated, adding that Elias 2-24 b proves current theoretical models are still missing crucial developmental processes.
To eliminate the possibility that a background star was tricking the instruments, researchers analyzed the relative motion of the luminous speck between 2018 and 2020. The statistical probability of an interfering background star causing the observed signal was calculated at just 0.015 percent. Because the planet sits roughly 54.9 astronomical units out from its host, it moved only about 1.5 degrees of its 360° orbital path during that initial two-year observation window.
What Lies Ahead for Orbit Tracking
Future observations will focus on mapping the exact orbital path of Elias 2-24 b. While the initial movement between 2018 and 2020 was too minute for precise current tracking, researchers calculate that the planet will have traversed approximately 6 degrees of its orbit by now. That wider arc falls well within the detection thresholds of modern and upcoming observatories, leaving the exact duration of its orbital period and its long-term trajectory as the next major questions for the scientific team.
