Our solar system is currently being graced by the presence of a bona fide alien: 2I/ Borisov, a comet that came from another star.
Its interstellar origins are not in any real doubt; it came screaming in from deep space so quickly there's no way it started here and somehow got a slingshotted gravitational boost from a planet. Wherever it came from, it ain't local.
But where, exactly? Not too long ago I wrote about a study where scientists backtracked its path, trying to figure out if it came from a nearby star. Their best bet was Kruger 60, a binary star currently about 13 light years from Earth. About a million years ago, the comet passed them by about 5 light years, and the authors call this a plausible source for it.
I disagree. 50 trillion kilometers is a long way. If it came from, say, a few hundred billion kilometers I'd be more inclined to agree. Even the extended cloud of comets around a star (called the Oort Cloud) tends to be roughly a trillion kilometers across, not 50. So I'm not swayed.
But new research was just published pointing to a different star. They find that 910,000 ...