Pluto

Pluto, the ninth planet in the Solar System, was accidentally discovered by the astronomer Clyde W. Tombaugh in Arizona on February 18, 1930.

• Facts about Pluto

  Pluto is the smallest planet
• Most often, it is farthest away from the sun, but sometimes Neptune is.
• Some astronomers believe that Pluto and its moon Charon are actually a "double planet", because Charon does not orbit around Pluto.

How big is the Pluto

Pluto is the smallest of all of the planets in the Solar System, weighing only 13,200,000,000,000,000,000,000 kilograms. While this may seem large, it's only about 1/500th of the Earth's mass. If you were to cut Pluto in half and measure the length on the inside, you'd find that Pluto is 2390 kilometers across, and with a little math you could figure out that its surface area is about 17,950,000 square kilometers (or 1/30th of the Earth's) and that its volume is 7,150,000,000 (or 1/15th of the Earth's).

What is Pluto's surface like?

We don't really know for sure. No spacecraft has ever been there, and Pluto is so far away from Earth that even the best telescopes can't see any detail. It is certainly very cold, about -230°C. The surface of Pluto is covered with ice, but not the same kind of ice that is found on Earth. The ice that covers Pluto is believed to be made mostly of nitrogen. Pluto also has a very thin atmosphere of nitrogen and methane which may freeze out when Pluto moves further from the Sun.

Some powerful telescopes like the Hubble Space Telescope have observed some seasonal changes as Pluto moved closer to the Sun and then moved further away, due to the nature of its orbit around the Sun.

What is Pluto's moon like?

Pluto has one moon: Charon. Charon is about half the size of Pluto in length and, much like Pluto, is believed to be covered with ice. Unlike Pluto, however, the ice covering Charon is thought to be made of water rather than nitrogen. In Roman mythology Charon ferried the shades of the dead across the river Lethe to the land of the dead.

How long is a day on Pluto

One day on Pluto is about 6.387 Earth days long. Like Uranus, Pluto also spins on its side.

How long is a year on Pluto

One year on Pluto would be about 90,613 days or 248 years on earth!

What is Pluto made of?

It is believed that Pluto is made mostly of rock and ice, although scientists will not be sure until more research is done on the planet. With the discovery of Charon, a good approximation of the average density of the planet can be determined, which can in turn suggest what Pluto is not made out of. If Pluto were made out of heavy minerals and iron like the planet Mercury, Pluto would have a very high density. Planets like Saturn are so thin and tenuous that their average density is less than even water. Pluto is somewhere in between, but more like some of the moons of the outer planets like Callisto or Triton, which are known to have quite a bit of water ice.

How much would Pluto's gravity pull on me?

If you were on Pluto, it would pull you down with a force less than one tenth as strong as Earth's gravity.

Who is Pluto named after?

Pluto was named after the Roman god of the underworld.

Is Pluto really a planet?

Some scientists say that Pluto isn't really a planet. They say it is too small, and point out that Charon (Pluto's satelite) is not much smaller than it. Some consider Pluto to be the largest known Kuiper belt object. Also, Pluto has a pattern of orbit around the sun that is different from other planets, and its orbit is affected somewhat by the gravitational pull of the nearby planet Neptune. Many Kuiper belt objects have orbits like that.