What is the Planet Pluto? | Types, Definition, Structure, Function & Facts
What is the Planet Pluto?
Until 2006, Pluto was considered the 9th planet in the solar system. At that time, the IAU (International Astronomical Union) gave the official definition of a planet. Pluto no longer qualifies as a planet under this definition and has been reclassified as a “dwarf planet”.
Pluto is a relatively small planet, smaller than Earth’s moon. Pluto is thought to consist of an ice mantle (mostly nitrogen ice), which makes up about 50% of its mass, and a rocky core, which makes up the remaining 50% of its mass.
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Pluto has a unique orbit around the sun. Instead of a circular or circular orbit around the sun like the eight planets, Pluto’s orbit is more egg-shaped. At its closest point to the sun, Pluto is about 2.8 billion kilometers away. At its furthest point, it is about 5 billion kilometers from the sun. When Pluto is closest to the sun, its atmosphere is thin. As Pluto moved away from the sun, it became so cold that the atmosphere began to freeze and fall to the ground.
Pluto has five named moons: Charon, Styx, Nix, Kerberos, and Hydra. The tallest is Charon. Charon’s diameter is about half that of Pluto. This makes it the largest moon in the solar system relative to the planet it orbits. Pluto and its moons are part of the Kuiper belt.
Highlights of Planet Pluto:
| Moons | 5 known |
| Mass | 2% of Earth’s mass |
| Diameter | 1473 miles (2370 km) |
| Year | 248 Earth years |
| Day | 6.4 Earth days |
| Average Temperature | minus, 388°F (-233°C) |
| Distance from the Sun | 3 – 5 billion miles from the sun (5 – 7.5 billion km) |
How does Pluto compare to Earth?
Pluto has a rock-hard surface like the Earth. It is much smaller than Earth. Pluto is so far away from the sun that it receives very little energy from the sun and is extremely cold.
How do we know about Pluto?
For nearly 100 years, scientists suspected there was a 9th planet somewhere beyond Neptune. This is based on changes in the orbits of Neptune and Uranus suggesting that a large mass is pulling the planets. They call this mysterious ninth planet Planet X.
In 1930, young astronomer Clyde Tombaugh found Planet X after a year of searching.
Since then, people have learned more about Pluto using telescopes. The first space probe to visit Pluto was New Horizons in 2015. New Horizons flew by Pluto less than 7,800 miles from the dwarf planet’s surface. He photographed and mapped the chemical composition of the surface of Pluto and its moon Charon.
Interesting Facts about the Dwarf Planet Pluto
Pluto’s strange orbit around the sun intersects the orbit of Neptune. As a result, during its 20 years in its 248-year orbit around the sun, Pluto was closer to the sun than Neptune.
Pluto was named by an 11-year-old girl, Venetia Burney. It takes its name from Pluto, the Roman god of the underworld.
It takes a radio signal traveling at the speed of light about 4 hours to travel from Earth to Pluto.
Pluto has an interesting orbit in that it orbits the Sun. Most of the planets, except Uranus, orbit like a crest relative to the Sun.
A person standing on Pluto would weigh about 1/15 of their weight on Earth.