What is Pluto?

Hi I'm Emerald Robinson. In this "What Is" video we're going to take a closer look at the dwarf planet known as Pluto.

Pluto was discovered in 1930 by American astronomer Clyde Tombaugh. It resides in the Kuiper Belt; a disc-like zone beyond Neptune which scientists believe contains remnants of the formation of the solar system.  Until 2006, Pluto was considered our solar system's 9th major planet.  However, in 2006 it was officially reclassified as a dwarf planet.  This makes it the second most massive dwarf planet known to be in our solar system.

Pluto is only 1,400 miles in diameter, and 4,494 miles in circumference.  This makes it smaller than the 8 major planets, and smaller than 7 moons in the solar system, including our own. Still somewhat a mystery, it is reddish-brown in color, comprised of mostly ice and rock and has five known moons. Pluto has approximately one-fifteenth the gravity of Earth; so if you weigh 120 pounds on Earth you would only weigh 18 pounds on Pluto.

Pluto has an eccentric elliptical orbit, and on average is more than 3.6 billion miles away from the sun... about 40 times further from the sun than Earth. For that reason it takes Pluto 248 years to revolve around the sun. One day on Pluto is about 6 1/2 days on Earth, and because of its great distance from the Sun's warm rays, the temperature on Pluto is 375 to 400 degrees below zero.

In 2006, scientists at the International Astronomical Union concluded that Pluto does not meet its definition of a planet. To meet that criteria a planet must: (a) orbit around the Sun, without being some other object's satellite (b) have its own sufficient mass, so that it assumes a nearly round shape, (c) and clear its orbital path of other orbiting bodies. Pluto meets two of these criteria but not the third.

That's because Pluto "crosses" inside of Neptune's orbit for 20 of the 248 years it and there appear to be asteroids in Pluto's orbit larger than it is.

Regardless of its official status, Pluto remains an intriguing orb in our solar system.