PLUTO
Dwarf Planet • A Frozen World Beyond Neptune
Welcome to the Pluto information file! Pluto is a small, icy dwarf planet located in the distant outer solar system. Once classified as the ninth planet, Pluto is now recognized as one of several dwarf planets that orbit the Sun beyond Neptune.
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DWARF PLANET OVERVIEW
Pluto is a small world made of rock and ice. It orbits the Sun in a region beyond Neptune called the Kuiper Belt, which contains many icy objects left over from the formation of the solar system.
Pluto was discovered in 1930 and was considered the ninth planet for many decades. In 2006, astronomers created a formal definition for planets and Pluto was reclassified as a dwarf planet.
Pluto was discovered in 1930 and was considered the ninth planet for many decades. In 2006, astronomers created a formal definition for planets and Pluto was reclassified as a dwarf planet.
☀ LOCATION
Pluto orbits beyond Neptune in the Kuiper Belt. Its average distance from the Sun is about 3.7 billion miles.
SIZE
Pluto has a diameter of about 1,477 miles. It is smaller than Earth's Moon and only a fraction of Earth's size.
CHARON
Pluto's largest moon, Charon, is so large compared with Pluto that the two worlds orbit a point in space located outside Pluto itself.
☁ ATMOSPHERE
Pluto has a very thin atmosphere made mainly of nitrogen, with smaller amounts of methane and carbon monoxide.
✦ PLUTO FAST FACTS ✦
| Classification | Dwarf Planet |
| Region | Kuiper Belt |
| Length of Year | About 248 Earth years |
| Length of Day | About 6.4 Earth days |
| Moons | 5 — Charon, Styx, Nix, Kerberos and Hydra |
| Rings | None known |
| Diameter | About 1,477 miles |
| Discovery | 1930 |
| Famous Feature | Tombaugh Regio, the heart-shaped region |
WHAT IS PLUTO LIKE?
Pluto is an extremely cold world covered in ice and frozen gases. Its surface includes mountains, plains, valleys and enormous regions of nitrogen ice.
One of Pluto's most recognizable features is a large bright heart-shaped region called Tombaugh Regio. Part of this region contains a vast plain of nitrogen ice called Sputnik Planitia.
Pluto also has mountains made largely of water ice. Some rise several miles above the surrounding terrain.
One of Pluto's most recognizable features is a large bright heart-shaped region called Tombaugh Regio. Part of this region contains a vast plain of nitrogen ice called Sputnik Planitia.
Pluto also has mountains made largely of water ice. Some rise several miles above the surrounding terrain.
★ DID YOU KNOW? ★
Pluto and its largest moon Charon are tidally locked to each other. This means Pluto always shows the same side to Charon, and Charon always shows the same side to Pluto.
Pluto and its largest moon Charon are tidally locked to each other. This means Pluto always shows the same side to Charon, and Charon always shows the same side to Pluto.
SPACECRAFT MISSION LOG
> DESTINATION: PLUTO
> NEW HORIZONS
NASA's New Horizons spacecraft became the first mission to visit Pluto when it flew past the dwarf planet in July 2015.
> PLUTO FLYBY
New Horizons returned the first detailed close-up images of Pluto and Charon, revealing mountains, glaciers, icy plains and surprisingly complex geology.
> TOMBAUGH REGIO
The spacecraft photographed Pluto's famous heart-shaped region in extraordinary detail, including the smooth nitrogen-ice plain Sputnik Planitia.
> KUIPER BELT
After passing Pluto, New Horizons continued farther into the Kuiper Belt to study other distant objects.
> STATUS:
EXPLORATION OF THE OUTER SOLAR SYSTEM CONTINUES...
> NEW HORIZONS
NASA's New Horizons spacecraft became the first mission to visit Pluto when it flew past the dwarf planet in July 2015.
> PLUTO FLYBY
New Horizons returned the first detailed close-up images of Pluto and Charon, revealing mountains, glaciers, icy plains and surprisingly complex geology.
> TOMBAUGH REGIO
The spacecraft photographed Pluto's famous heart-shaped region in extraordinary detail, including the smooth nitrogen-ice plain Sputnik Planitia.
> KUIPER BELT
After passing Pluto, New Horizons continued farther into the Kuiper Belt to study other distant objects.
> STATUS:
EXPLORATION OF THE OUTER SOLAR SYSTEM CONTINUES...