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trans-Neptunian object

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trans-Neptunian object

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Also known as TNO, object beyond Neptune, transneptunian object

any object in the Solar System that orbits the Sun at a greater average distance than Neptune

AI overview

A trans-Neptunian object is anything in our Solar System that orbits the Sun farther away than Neptune does. Scientists study these distant objects to better understand the structure and history of our Solar System, including how planets formed and what icy bodies exist in its outer regions.

AI-generated from the Wikipedia summary — may contain errors.

~21 min read

Encyclopedic overview

A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU).

Typically, TNOs are further divided into the classical and resonant objects of the Kuiper belt, the scattered disc and detached objects with the sednoids being the most distant ones. As of February 2025, the catalog of minor planets contains 1006 numbered and more than 4000 unnumbered TNOs. However, nearly 5900 objects with semimajor axis over 30 AU are present in the MPC catalog, with 1009 being numbered.

Excerpted from Wikipedia’s “trans-Neptunian object” article, available under the CC BY-SA 4.0 licence.

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