Astronomers have confirmed the youngest exoplanet ever found. The planet, named Elias 2-24b, orbits a star less than 1 million years old, offering a rare glimpse into planetary formation. The discovery was led by Andrea Bernardi at Diego Portales University in Chile, who reanalyzed coronagraph data from the W.M. Keck Observatory collected in 2018 and 2020.
Elias 2-24b lies about 450 light-years from Earth and orbits its star at roughly 55 times the Earth-Sun distance. Its mass is estimated at 1.9 to 4.0 times that of Jupiter, though its volume is likely smaller. The planet's youth is striking: the previous youngest directly observed exoplanets, around the stars PDS 70 and WISPIT 2, are over 5 million years old.
The find challenges the standard core accretion model, which holds that a Jupiter-sized planet at such a distance should take millions of years to form. Coauthor Lucas Siesa said the planet shows that 'even our best planet-formation models are still missing some important processes.' The team believes the planet did form through core accretion, but faster than expected.
The discovery comes as new instruments are coming online. NASA's Nancy Grace Roman Space Telescope, launched in August, carries a more powerful coronagraph than the one used here. Astronomers expect it to reveal more young planets and to push planet hunting into a new era. 'This is just the beginning of a new era of discovery,' Siesa said.