Interstellar Comet 3I/ATLAS Weighs Over 33 Billion Tons, Harvard Astrophysicist Suggests Possible Alien Origin

The interstellar object 3I/ATLAS, first observed in July 2025, is only the third such object detected after 'Oumuamua and 2I/Borisov. Harvard astrophysicist Avi Loeb and his team have reported that 3I/ATLAS is anomalously massive, with an estimated mass exceeding 33 billion tons and a nucleus at least 3.1 miles across, making it significantly larger than previous interstellar objects. The comet is shedding large amounts of carbon dioxide and dust as it speeds toward the Sun on a straight trajectory, and exhibits a slight non-gravitational acceleration due to outgassing. Loeb has speculated that the object's unusual mass, size, and trajectory could indicate it is a technological artifact or alien technology rather than a typical comet. NASA and other space agencies are collecting further data, including observations from Mars orbiters and the James Webb Space Telescope, to better understand the object's nature. While the scientific community mostly regards 3I/ATLAS as a natural comet with unusual characteristics, its anomalous features keep open the possibility of an extraterrestrial origin.