A team of astronomers from the Massachusetts Institute of Technology has discovered a planet some 140 light-years from Earth that is rapidly disintegrating, producing a comet-like tail. The planet, dubbed BD+05 4868 Ab, has a mass similar to Mercury and orbits its star approximately 20 times closer than Mercury does to the sun.
The discovery was made using NASA’s Transiting Exoplanet Survey Satellite (TESS), which monitors nearby stars for transits – periodic dips in starlight that could be signs of orbiting exoplanets. The signal detected by the team was unusual, with a transit that fluctuated in depth every 30.5 hours.
According to researchers, BD+05 4868 Ab is experiencing a dramatic rate of disintegration, shedding material equivalent to one Mount Everest each time it orbits its star. At this pace, given its small mass, the planet is predicted to completely disintegrate in about 1 million to 2 million years.
The scientists believe that the planet’s low mass and weak gravity are contributing to its rapid demise. The team suspects that there is very little gravity holding the planet together, which leads to a runaway process of mass loss and further weakening of gravity.
This discovery adds to the list of three other disintegrating planets found in our solar system and beyond, all spotted over 10 years ago using data from NASA’s Kepler Space Telescope. The planet BD+05 4868 Ab has the longest tail and deepest transits among these four known disintegrating planets.
The researchers plan to conduct further observations using NASA’s James Webb Space Telescope (JWST) to determine the mineral makeup of the dust tail and gain insights into the diversity and potential habitability of terrestrial planets outside our solar system.
Source: https://phys.org/news/2025-04-astronomers-planet-rapidly-disintegrating-comet.html