Trans-Neptunian object facts for kids

Eris and its moon Dysnomia are both Trans-Neptunian Objects

A Trans-Neptunian object (or TNO) is a space object that orbits the Sun further away than the planet Neptune. Think of it as a distant neighbor of our Solar System's planets. These objects are usually small, like minor planets, but some are quite large. Astronomers have found over a thousand of these objects so far. Many of them are found in a special area called the Kuiper belt.

The Solar System
Sun • Heliosphere	Planets ☾ = moon(s) ∅ = rings		Mercury	Venus	Earth ☾	Mars ☾
			Jupiter ☾ ∅	Saturn ☾ ∅	Uranus ☾ ∅	Neptune ☾ ∅
	Dwarf planets		Ceres	Pluto ☾	Haumea ☾	Makemake
			Eris ☾
	Small Solar System bodies	Asteroids (minor planets)	Groups and families: Vulcanoids · Near-Earth asteroids · Asteroid belt Jupiter Trojans · Centaurs · Neptune Trojans · Asteroid moons · Meteoroids · Pallas · Juno · Vesta · Hygiea · Interamnia · Europa
			See also the list of asteroids.
		Trans- Neptunians	Kuiper belt – Plutinos: Orcus · Ixion – Cubewanos: Varuna · Quaoar · Huya
			Scattered disc: Sedna
		Comets	Periodic comets and non-periodic comets Damocloids · Oort cloud
See also the list of solar system objects

What are Trans-Neptunian Objects?

Trans-Neptunian objects are icy worlds that travel around the Sun. They are located in the outer parts of our Solar System. This means they are much farther from the Sun than Earth or even Neptune. These objects are often made of ice, rock, and other frozen materials.

Where are TNOs found?

Most TNOs are found in two main areas:

• The Kuiper Belt: This is a large ring-shaped region beyond Neptune. It's similar to the asteroid belt, but much bigger. It contains many icy bodies, including Pluto.
• The Scattered Disc: Some TNOs are in an even more distant region. Their orbits are very stretched out and tilted. This area is called the Scattered Disc.

Why are TNOs important?

Studying TNOs helps scientists learn about the early days of our Solar System. These objects are like frozen time capsules. They have probably not changed much since the Solar System formed billions of years ago. By studying them, we can understand how planets and other bodies came to be.

Famous Trans-Neptunian Objects

Many interesting TNOs have been discovered. Some are even considered dwarf planets.

Pluto

Pluto is perhaps the most famous TNO. For many years, it was called the ninth planet. However, in 2006, scientists reclassified it as a dwarf planet. Pluto is located in the Kuiper Belt. It has five known moons, with Charon being the largest. The New Horizons spacecraft flew past Pluto in 2015. It sent back amazing pictures and data.

Eris

Eris is another well-known TNO. It is one of the largest dwarf planets. Eris is even more distant than Pluto. It has one moon named Dysnomia. The discovery of Eris helped scientists decide to create the dwarf planet category.

Other notable TNOs

• Makemake: This dwarf planet is also in the Kuiper Belt. It is one of the largest known TNOs after Pluto and Eris.
• Haumea: This dwarf planet is unusual because it spins very fast. This fast spin makes it look stretched out, like a rugby ball. It also has two moons and a ring.
• Arrokoth: This TNO was visited by the New Horizons spacecraft in 2019. It is a very ancient object. It looks like two connected spheres.

How are TNOs found?

Finding TNOs is very difficult. They are small and very far away. This means they are very faint. Astronomers use powerful telescopes to search for them. They take many pictures of the night sky. Then, they look for tiny dots that move slowly against the background stars. This slow movement tells them that the object is in our Solar System.

Images for kids

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  Pluto imaged by New Horizons

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  Looking back at Pluto, the largest visited KBO so far

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  Kuiper belt object 486958 Arrokoth, in images taken by the New Horizons spacecraft

See also

In Spanish: Objeto transneptuniano para niños