Trans-Neptunian object

Definition

A trans-Neptunian object (TNO) is any minor planet or dwarf planet in the Solar System that orbits the Sun at a greater average distance than Neptune. These objects are primarily found in the Kuiper Belt and beyond, including the scattered disc and inner Oort cloud regions.

5 Must Know Facts For Your Next Test

1. Trans-Neptunian objects include well-known bodies like Pluto, Eris, and Haumea.
2. The Kuiper Belt is the main region where TNOs are located, extending from about 30 to 55 astronomical units (AU) from the Sun.
3. TNOs can vary greatly in size, with some being only a few kilometers in diameter while others like Eris are nearly as large as Pluto.
4. Many TNOs have highly elliptical and inclined orbits compared to the planets within Neptune's orbit.
5. The study of TNOs helps astronomers understand the early solar system's formation and migration processes.

Review Questions

• What defines an object as a trans-Neptunian object?
• Name three well-known trans-Neptunian objects.
• Why are trans-Neptunian objects significant for understanding the early solar system?

Related terms

Kuiper Belt: A region of the Solar System beyond Neptune filled with small icy bodies including many TNOs.

Scattered Disc: A distant area of the Solar System populated by icy minor planets with more eccentric and inclined orbits than those in the Kuiper Belt.

Oort Cloud: A hypothetical distant spherical shell of icy bodies believed to surround the Solar System at distances up to 100,000 AU from the Sun.