Trajectory class · e ≈ 1

Near-Parabolic Orbit

An orbit with eccentricity very close to 1 — the boundary between bound and unbound. Long-period comets falling in from the Oort cloud on their first passage follow near-parabolic orbits. A near-parabolic orbit signals a distant Solar-System origin, not an interstellar one.

Definition

Eccentricity near 1 — right at the escape boundary; typical of first-time Oort-cloud comets.

The eccentricity ladder

Orbits run from bound and elliptical, through the parabolic boundary, to the strongly hyperbolic trajectories of interstellar objects.

Hyperbolic Orbit (Solar-System Origin) →

Objects on this trajectory

C/1999 S4 (LINEAR)
Near-parabolic (e ≈ 1) — a long-period comet
Hyperbolic (Solar-System origin)
C/2007 W1 (Boattini)
Near-parabolic (e ≈ 1) — a long-period comet
Hyperbolic (Solar-System origin)
C/2017 K2 (PANSTARRS)
Near-parabolic (e ≈ 1) — a dynamically new comet
Hyperbolic (Solar-System origin)

Sources

Facts on this topic will be cited from these primary and reference sources.

NASA JPLJet Propulsion Laboratory / Solar System Dynamics
Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.
NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.

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