Exoplanet hunters scouring space for worlds around other stars have found the youngest planet on record.
This Jupiter-size planet, about 450 light-years away from Earth, is less than 1 million years old. That’s much younger than the previous record holders — four worlds tied at about 5 million years old each.
Astronomers confirmed this detection by reviewing NASA-funded archives from the W.M. Keck Observatory’s coronagraph, an instrument that blocks a star’s light to reveal faint objects hiding in its glare.
When they looked at the Hawaiian telescope’s observations from 2018 and 2020, they saw what two other major observatories had already spotted: a baby, still snuggled up in its nest of gas, dust, rock, and icy bits. The world is called Elias 2-24 b.
“The galaxy churns out new stars and planets continuously,” said Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos in Chile, in a statement, “but there is a large gap in what most telescopes can detect. We are mostly blind to these baby planets right now.”
Researchers went back to the archives because of some unsettled business. Two major Chilean telescopes, the Atacama Large Millimeter/submillimeter Array and the European Southern Observatory’s Very Large Telescope, had seen what looked like an empty ring of space around the distant Elias 2-24 star, along with a faint point of light in that “empty” band.
When those observations occurred a decade ago, astronomers were doubtful. Leading planet-formation theories estimate that it takes about 5 million years to make a Jupiter-size planet, and even longer for worlds farther out from their stars. Elias 2-24 b defies those predictions, orbiting its star 10 times farther than Jupiter circles the sun.
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An ALMA observatory radio image of Elias 2-24, a young star surrounded by dust and gas that might be forming stars, taken in 2016.
Credit: Lucas A. Cieza, et al. / DOI 10.3847/2041-8213/aa9b7b
But baby Elias 2-24 b behaved like a planet and was in the right place, said Andrea Bernardi, a doctoral student at the Universidad Diego Portales in Chile, who led the study. It sits in a gap created precisely because a massive body is plowing gas and dust out of its way as it orbits. The study results appear in The Astrophysical Journal Letters.
Confirmation of Elias 2-24 b means current planet formation models for planet formation are lacking some key factors, the researchers said.
Since astronomers can’t watch a planet’s entire life from beginning to end, they piece together planetary life cycles by studying many worlds at different stages. The problem is scientists have less information than they’d like about baby planets because they’re intrinsically hard to observe: Newborn worlds are swaddled in dust that blocks telescopes from seeing them.
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New telescopes like NASA’s Nancy Grace Roman Space Telescope, should make these detections easier. Roman launched on Aug. 30 and is en route to the second sun‑Earth Lagrange point, or L2, the same million-mile-away destination where the James Webb Space Telescope orbits. After calibration, Roman will release its first images around Jan. 2027.
Exoplanets are so dim compared to their stars they might as well be invisible. Almost all exoplanet discoveries so far rely on indirect techniques. But as technology for directly photographing planets improves, astronomers have hope that we’ll eventually be able to snap pictures of Earth-size worlds in the warmth of their stars.
Roman boasts a coronagraph far more advanced than those on Hubble, Webb, and ground‑based telescopes, said Vanessa Bailey, NASA’s coronagraph scientist for the telescope. She hopes the instrument will be able to take images of worlds as small and faint as our own Jupiter — a challenging feat since the exoplanets other coronagraphs have managed to capture are bigger and brighter.
“What astronomers can do today with coronagraph instruments is see planets that are maybe 1 million times fainter than their stars,” Bailey told Mashable. “What we’re doing with the Roman coronagraph is hopefully getting to 10 million to 100 million times fainter, maybe even a little bit more in the best‑case scenario.”
