Discovery of the third interstellar object passing through our Solar System. It is 3I/ATLAS (or C/2025 N1 ATLAS or also A11pl3Z), discovered by ATLAS (Asteroid Terrestrial-impact Last Alert System) in Rio Hurtado, Chile. It is likely a comet, but with a very high velocity of 58 km/s while still 4.5 astronomical units from the Sun. It has a 68% chance of being between 7.6 and 14 billion years old, making it older (or much older) than the Solar System. On July 16, 2025, astrophysicist Avi Loeb of Harvard University and other researchers from the Initiative for Interstellar Studies published a paper on arXiv speculating that 3I/ATLAS could be an extraterrestrial spacecraft, believing the object has peculiar and anomalous characteristics, such as its apparently large size, a lack of identifiable chemicals, and a trajectory aligned with the ecliptic plane of the Solar System. Other astronomers, including Chris Lintott of the University of Oxford, immediately criticized Loeb’s speculation; the science news website Live Science reports that “the overwhelming consensus is that it is a comet.” Loeb has previously argued that other unusual interstellar objects like Oumuamua could be extraterrestrial spacecraft, a claim that has drawn criticism from many researchers.
