James Cameron might be an iconic director now, but in the early '80s, he was a little-known creator just starting. His first film, 1982's Piranha II: The Spawning, wasn't great, to put it mildly.

For months, scientists and the public have squinted their eyes at photos of a blurry smudge to figure out if it’s proof that aliens exist. Discovered in July, 3I/ATLAS is not your average comet – it’s ...