Astronomers Identify Youngest Exoplanet Ever Detected at Just One Million Years Old

Astronomers have identified Elias 2-24 b, a juvenile exoplanet that stands as the youngest alien world ever directly observed. Forming less than one million years ago, the planet orbits a nascent star approximately 450 light-years from Earth. With a mass ranging between two and four times that of Jupiter, it resides nearly twice the distance from its host star that Neptune maintains from our sun.

Initial evidence of this massive planetary infant emerged in 2017, when researchers noticed a distinct gap within the protoplanetary disk surrounding the star. These disks consist of swirling gas, dust, and stellar debris remaining from a star’s birth. The gap strongly suggested that gravitational clumping of disk material had coalesced into a planet, though direct visualization remained impossible at the time.

In a study published September 16 in The Astrophysical Journal Letters, scientists combined data from three major observatories: the W. M. Keck Observatory in Hawaii, the Atacama Large Millimeter/submillimeter Array in Chile, and the European Southern Observatory’s Very Large Telescope, also in Chile. This multi-instrument approach allowed the team to directly image Elias 2-24 b and confirm its youth.

“What makes Elias 2-24 b so remarkable is its age,” said Andrea Bernardi, the study’s lead author and a doctoral student at the Institute of Astrophysical Studies at Diego Portales University in Chile. “This is the youngest planet detected so far, and because it is still actively accreting material from its surroundings, we’re able to observe a stage of planet formation that is rarely seen directly.”

The discovery marks a significant advancement in planetary science. Elias 2-24 b is roughly 5,000 times younger than Earth and represents merely 0.008% of the age of PSR B1620-26 b, known as “Methuselah,” which is the oldest known exoplanet at approximately 11 billion years old. Relative to a human lifespan, the new find is comparable to a baby only two or three days old.

While previous record-holders for youngest exoplanets, such as those orbiting the star PDS 70, were around 5 million years old, advancements in telescope technology have pushed these boundaries. In 2024, TIDYE-1b was discovered at an estimated 3 million years old, followed by AB Aurigae b in 2025, which may be as young as 2 million years. Elias 2-24 b is at least twice as young as either of these predecessors.

Lucas Cieza, an astronomer at the Institute of Astrophysical Studies who led the 2017 research initially spotting the disk gap, noted the implications for current theories. “Our planet-formation models already struggled to explain the previous record holders for the youngest known planet,” Cieza said. “Elias 2-24 b shows us that even our best planet-formation models are still missing some important processes.”

Most of the over 6,000 known exoplanets have been detected via the transit method, which observes dips in stellar brightness as a planet passes in front of its star. However, this technique is ineffective for planets embedded within protoplanetary disks, as the dense debris clouds permanently dim starlight when viewed edge-on. Furthermore, detecting young planets requires the disk to be oriented perpendicular to Earth, a configuration that is difficult to identify because stellar glare often overwhelms the disk’s faint light.

Looking ahead, NASA’s Nancy Grace Roman Space Telescope, launched on August 30, promises to revolutionize the field. Currently undergoing calibration, the telescope features a advanced coronagraph designed to block stellar light, facilitating the study of surrounding environments. Experts anticipate Roman could detect up to 100,000 new exoplanets with reduced bias toward older worlds.

“This is just the beginning of a new era of discovery,” Cieza stated. “Roman will take planet hunting to the next level.”