[cripplecreek]

I have to wonder if we would recognize an extrasolar comet if we managed to sample one. I suppose that's one of the reasons we're looking at our own native comets.

[Pyro7480]

The comet featured at this link will probably become extrasolar.

[SunkenCiv]

Pyro7480's link shows a comet on a hyperbolic trajectory, which is a comet just passing through. They are unusual, but do occur. Comets on parabolic trajectories are said to be confined to the Solar System. Presumably a comet could (while passing through) have one or more encounters (say, with Jupiter), thus altering their trajectories, leading to a parabolic trajectory. But I dunno.