NASA’s James Webb Space Telescope has uncovered a giant planet that had been hiding in plain sight within one of the most closely studied planetary systems beyond our solar system.
The newly discovered world, called Beta Pictoris d, orbits the young star Beta Pictoris, about 63 light-years from Earth.
The discovery, published in The Astrophysical Journal Letters, makes Beta Pictoris only the second known planetary system where at least three planets have been directly detected.
Beta Pictoris has fascinated astronomers for decades because it is only about 23 million years old, making it a relatively young star.
It is surrounded by a large disk of dust and rocky debris left over from the formation of its planets, giving scientists a rare opportunity to watch how young planetary systems develop.
Two giant planets, Beta Pictoris b and Beta Pictoris c, were already known to orbit the star.
The newly found Beta Pictoris d is believed to be at least twice as massive as Jupiter, making it the smallest of the three known giant planets in the system.
Researchers estimate that it orbits its star at a distance similar to Neptune’s orbit around the Sun. Although it has the widest orbit of the three planets, it still travels inside the inner edge of the system’s dusty debris disk.
Interestingly, the research team was not searching for another planet. They were using Webb’s Near-Infrared Spectrograph (NIRSpec) to study the atmosphere of Beta Pictoris b when they noticed an unusual signal hidden in the data. Instead of finding only light reflected by dust, they detected a distinctive pattern created by carbon monoxide gas, a clear sign of a giant planet’s atmosphere.
This method is different from the traditional way of directly imaging planets, which usually relies on spotting a faint point of light next to a bright star. By studying the planet’s unique chemical “fingerprint,” scientists were also able to measure its motion and confirm that it was orbiting Beta Pictoris rather than being a distant background object.
To strengthen the discovery, the team later observed the planet using Webb’s Mid-Infrared Instrument (MIRI). These follow-up observations detected water vapor and methane in the atmosphere, providing even stronger evidence that the object is indeed a giant planet while also revealing more about its atmospheric makeup.
Beta Pictoris d remained hidden for so long because the star’s thick dust disk scatters light, making it difficult for ordinary imaging techniques to separate planets from the surrounding material. Webb’s spectroscopic observations were able to cut through this confusion by focusing on the planet’s atmospheric molecules instead of its brightness.
Scientists believe the newly discovered planet may also explain some unusual features seen in the debris disk, including its sharply defined inner edge. More importantly, the discovery highlights a powerful new way to search for exoplanets. Instead of relying only on direct images, astronomers can now use the chemical signatures in a planet’s atmosphere to uncover worlds that might otherwise remain invisible.
Future Webb observations will help researchers better measure Beta Pictoris d’s temperature, atmosphere and orbit, offering new clues about how young planetary systems form and evolve.
