NASA has responded to claims – popularized by Harvard professor Avi Loeb – that the interstellar object 3I/ATLAS is a spacecraft sent to the Solar System by an advanced alien civilization. On July 1, 2025, astronomers spotted an object moving through the Solar System at nearly twice the velocity of previous interstellar visitors ‘Oumuamua and Comet Borisov. The object, which was confirmed to be an interstellar comet with its own dusty coma, is far larger than the previous two, with an estimated nucleus (the rocky part of the comet, excluding its coma) of around 5.6 kilometers (3.5 miles). Early work...