Researchers identify South Atlantic fireball as likely interstellar meteor

Bright fireball over British Columbia, Canada at UTC on April 29, 2026. Credit: Michael Roth A fireball detected over the South Atlantic Ocean at UTC on April 1, 2026, has emerged as a candidate interstellar meteor following an orbital analysis , who argue that its trajectory is inconsistent with an origin within the Solar System. The object, designated Polar-IM, is described (CNEOS) fireball database, with a confidence level above 99.9997% under the researchers’ uncertainty model. The event reached peak brightness at an altitude of 90.5 km (56.2 miles) near 41.9°S and 54.7°W, east of Argentina. Data released through the CNEOS fireball database list Earth-fixed velocity components of +3.6 km/s, -34.6 km/s, and +59.8 km/s, along with a reported radiated energy of 2.4 × 1010 J and a calculated impact energy of 0.086 kt. The database notes that the measurements are derived from U. Government sensor detections and should be used with caution because CNEOS does not independently verify or reanalyze the reported events. After transforming the Earth-fixed velocity vector into heliocentric coordinates and accounting for Earth’s gravitational influence, Loeb and Cloete calculated a heliocentric speed of 51.73 km/s (32.14 miles/s) and a heliocentric excess speed of 30 km/s (18.6 miles/s). Their calculations produced an orbital inclination of 89.4 degrees, placing the trajectory nearly perpendicular to the plane of the Solar System. They also found that the velocity component perpendicular to the Solar System plane exceeded the local solar escape speed on its own. To test the result, the researchers ran 1 million Monte Carlo simulations using an empirical post-2018 CNEOS error model developed in an earlier study. According to the researchers, none of the simulated trajectories produced a bound heliocentric orbit. The team reported a margin-to-scatter ratio of 12.82 sigma under their uncertainty model. The event was already present in the publicly available CNEOS database. Loeb and Cloete’s analysis identified it as a candidate interstellar meteor based on its reconstructed trajectory. Based on the event’s reported impact energy and inferred velocity, Loeb estimated that Polar-IM had a mass of about 150 kg (331 lb) and a diameter of roughly 0.5 m (1.6 feet). Polar-IM would join a short list of known interstellar visitors that includes 1I/’Oumuamua, 2I/Borisov, and 3I/ATLAS. Unlike those objects, which were identified telescopically while passing through the Solar System, Polar-IM was identified through analysis of a fireball recorded during atmospheric entry. Loeb compared the event with the 2014 interstellar meteor candidate IM1, which was the focus of a 2023 ocean expedition that recovered metallic spherules from the seafloor that he and collaborators have argued are associated with the object.