Astronomers confirm Elias 2-24b is youngest known exoplanet

Astronomers have confirmed the discovery of the youngest known exoplanet, Elias 2‑24b, which is less than one million years old. The planet orbits a young star in the Lupus star‑forming region about 450 light‑years from Earth. Scientists spotted the planet with the Atacama Large Millimeter/submillimeter Array (ALMA), which detected a dark gap in the dusty disc around the star that is the signature of a planet carving out its orbit.

The find matters because it pushes the lower limit of how quickly planets can form. Most models say it takes several million years for a planet to grow from dust to a few times Earth’s mass. Seeing a planet so young suggests that the process can begin much sooner, possibly in just a few hundred thousand years. It also shows that planets can form while their host stars are still accreting material, which may change how we think about the timing of planet formation and the early environments of planetary systems.

Elias 2‑24b was first hinted at in 2018 when ALMA saw a gap in the disc of its host star. Follow‑up observations in 2023 confirmed that the gap was caused by a planet, not a shadow or a dust clump. The planet’s mass is estimated at about 5–10 times that of Earth, and its orbit lies roughly 10 astronomical units from the star, a distance similar to the orbit of Saturn around the Sun. The team used high‑resolution imaging to measure the width of the gap and the temperature of the surrounding dust, which together give a good estimate of the planet’s size and age.

Researchers will next use the James Webb Space Telescope and the Extremely Large Telescope to study Elias 2‑24b in more detail. They plan to look for signs of an atmosphere and to measure the planet’s temperature and composition. The data will help refine models of planet formation and could reveal whether many young systems host planets that form quickly. If more planets like Elias 2‑24b are found, it could mean that planet birth is a rapid, common event in the early lives of stars.