Dwarf Planet · Updated May 2026
Pluto.
Pluto is a dwarf planet in the Kuiper Belt, the first such object ever discovered, and the largest known. With a diameter of 2,377 km it is smaller than Earth's Moon. Its 248-Earth-year orbit is so eccentric (e = 0.249) that for 20 years of every orbit Pluto is closer to the Sun than Neptune. Reclassified from "planet" to "dwarf planet" by the IAU in 2006, it has five moons; the largest, Charon, is so massive that the two orbit a barycentre outside Pluto itself.
Open Pluto in the viewer →Key facts
Pluto and Charon are tidally locked to each other — they always show the same face. From Pluto, Charon hangs motionless in the sky, and from Charon, Pluto hangs motionless. The viewer renders this correctly: in real-time mode the two stay locked as they orbit their shared centre.
Atmosphere
Thin nitrogen-methane atmosphere, varying from 0.1 to 1 Pa as Pluto moves nearer or farther from the Sun. As Pluto recedes through the rest of the 2020s and 2030s, much of the atmosphere is expected to freeze onto the surface.
Surface
A surprise from New Horizons (2015): vast nitrogen-ice plains (Sputnik Planitia, the heart-shaped feature), water-ice mountains up to 3.5 km tall, possible cryovolcanoes, and active geology despite the tiny scale.
Interior
Likely a rocky core surrounded by a water-ice mantle, with hints of a subsurface ocean detected from surface tectonics.
Formation
Formed in the outer protoplanetary disc 4.5 billion years ago, in the same population as the rest of the Kuiper Belt. Charon may have formed from a giant impact, similar to Earth's Moon.
Orbit
Average distance from the Sun: 5.91 billion km (39.5 AU). Orbital period 248 Earth years. Tilted 17° from the ecliptic and so eccentric that 20 years of each orbit are inside Neptune's — though the two never collide because of a stabilising 2:3 orbital resonance.
Major moons
- Charon — Charon is Pluto's largest moon, so large relative to Pluto that they orbit a common center of gravity.
Notable missions
- New Horizons (2015 · Past flyby) — The only spacecraft ever to visit Pluto. Continued outward to fly past Arrokoth in 2019.
How to view Pluto in 3D
This page is part of an interactive 3D solar system viewer built with Three.js, WebGL 2.0, and custom GLSL shaders. Pluto orbits the Sun in real time alongside every other planet, with adjustable time speed, scale sliders, and a fly mode that lets you pilot a spacecraft between bodies under realistic gravity.
Fly to Pluto now →Frequently asked questions
Why is Pluto not a planet?
The IAU's 2006 definition requires a planet to have "cleared its orbital neighbourhood." Pluto shares its orbital region with thousands of other Kuiper Belt objects.
How many moons does Pluto have?
Five: Charon, Styx, Nix, Kerberos, and Hydra.
How long is a year on Pluto?
248 Earth years.
Sources & methodology
Numbers cross-referenced with the sources below; surface and atmosphere descriptions reflect findings as of May 2026. Renderings in the 3D viewer use textures based on Solar System Scope and NASA imagery.