Hyperbolic Comets

A long-period comet that a close encounter with Jupiter in 1980 flung onto a clearly hyperbolic orbit (eccentricity about 1.06). It is now leaving the Solar System, but — unlike a true interstellar object — it formed here; the hyperbolic orbit is the result of a planetary slingshot, not an origin around another star.

Trajectory

Weakly hyperbolic (e ≈ 1.06) after a Jupiter encounter

Discovered

1980-02-11

A near-parabolic long-period comet from the Oort cloud, famous for disintegrating completely near perihelion in July 2000 — one of the best-observed comet break-ups. Its orbit was close to the parabolic boundary (eccentricity near 1), the hallmark of a first-time visitor from the distant Solar System, not from interstellar space.

Trajectory

Near-parabolic (e ≈ 1) — a long-period comet

Discovered

1999-09-27

A long-period comet discovered by Andrea Boattini through the Mount Lemmon Survey, on a near-parabolic orbit with an eccentricity extremely close to 1. Like the other long-period comets here it is a distant Solar-System visitor, not an interstellar object: its original orbit is bound and it is not being ejected from the Solar System — the tiny excess over a parabola is an epoch-dependent, perturbed value.

Trajectory

Near-parabolic (e ≈ 1) — a long-period comet

Discovered

2007-11-20

A dynamically new, near-parabolic long-period comet discovered by Pan-STARRS in 2017 and notable for showing activity at a record distance — a coma was detected beyond Saturn's orbit, on the comet's first passage in from the Oort cloud. Its near-parabolic orbit marks it as a distant Solar-System visitor, not an interstellar object.

Trajectory

Near-parabolic (e ≈ 1) — a dynamically new comet

Discovered

2017-05-21