Comment by perihelions

The last billion over the past billion years could each, also, have been hostile alien probes. It's only now that we've the ability to observe them, in the past ~10 years, a cosmic blink, that we tangibly observe what's been going on all this time. (If we go and burn down the astronomy observatories, this will never happen again!)

That Harvard guy's such an attention-seeking clown.

(Worth remarking there's nothing fundamentally novel about observing comets from interstellar space; that's been predicted for centuries. Because it's ancient knowledge that certain comets are observed *departing* the solar system, into interstellar space; so why shouldn't we expect the same to happen in reverse, symmetrically? It's just a question of number statistics).