he comet known as Oumuamua (Hawaiian for “visitor from afar”) sailed through our solar system in 2017, and right away made news. Its small size—barely a quarter-mile And there was one other thing about Oumuamua that caught astronomers’ eyes: it sped up when it was leaving the solar system, far more than ordinary comets do when they’re flung away by the sun’s gravity. That led to some wild speculation that Oumuamua might be an alien vehicle buzzing our solar system.
