Detection method

Incoming-Trajectory Analysis

Determining an object's orbit from astrometry and tracing its path backward. An unbound, strongly hyperbolic incoming trajectory — arriving from interstellar space rather than from the planetary region — establishes that the object was not on a closed Solar orbit. The direction it came from (its radiant) can also be identified, though no specific parent star has been pinned down for any interstellar object.

In brief

Fitting an orbit to astrometric positions and running it backward to show the object arrived unbound from outside the planetary region.

Objects identified this way

1I/ʻOumuamuaConfirmed interstellar
3I/ATLASConfirmed interstellar

Sources

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

Minor Planet CenterIAU Minor Planet Center
Designations and orbits of asteroids, comets, and minor bodies.
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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