The International Astronomical Union decided the rules to what makes a planet. If it did not fit the criteria, they were given the name of a dwarf planet.
The three factors that are required to be called a planet are, firstly it has to orbit the Sun, secondly its shape should resemble a ball like figure, and lastly it has to clear the area around its orbit by pushing other objects out of its way with its impressive size and gravity.
Pluto was known as a planet up until 2006, but the International Astronomical Union decided because of its size it doesn’t have enough gravity to clear objects out of its way, so it was redefined as a dwarf planet.
There are officially five recognized dwarf planets in the Solar System. They are called, Ceres, Pluto, Haumea, Makemake and Eris.
Outside of the Solar System, there could be millions of Dwarf Planets similar to what is in it, but because of its vast distance, we just haven’t found them yet, even with the current technology available to us nowadays.
There are many more dwarf Planets in the Solar System awaiting confirmation.
The Solar System consists of the Sun, and everything bound to it by gravity, including planets and their moons, asteroids, dwarf planets, the Kuiper belt objects, meteoroids, comets and interplanetary dust.
Ceres is the closest dwarf planet to the Sun and lives in the Asteroid belt. It was discovered by astronomer Giuseppe Piazza in 1801.
Pluto is the second closest dwarf planet to the Sun and lives in the Kuiper Belt. It was discovered by astronomer Clyde W. Tombaugh in 1930.
Haumea is the third closest dwarf planet to the Sun and lives in the Kuiper Belt. It was discovered by a team of scientists in 2004.
Makemake is the fourth closest dwarf planet to the Sun and lives in the Kuiper Belt. It was discovered by a team of scientists in 2005.
Eris is the Fifth closest dwarf planet to the Sun and lives in the Kuiper Belt. It was discovered by a team of scientists in 2005.
Pluto is just one of tens of thousands of frozen dwarf planets and asteroids in an area of the Solar System, called the Kuiper Belt.
The asteroid belt is a area of space between the orbits of Mars and Jupiter, where most of the asteroids in our Solar System are found orbiting the Sun. It most probably contain millions of asteroids.
Eris is the largest dwarf planet measuring 1,445 miles in diameter.
Ceres is the smallest dwarf planet measuring 587 miles in diameter. While it is the smallest plant, it is the largest object in the Asteroid Belt.
Of all the dwarf planets, only 2 have been visited by space probes. In 2015, NASA’s Dawn and New Horizons missions reached Ceres and Pluto.
The order of the dwarf planets closest from the Sun outwards is Ceres, Pluto, Haumea, Makemake and then Eris being the furthest from the Sun.
The orbit periods for the dwarf planets on its travels around the Sun is, Ceres 4.6 years, Pluto 248 years, Haumea 283.3 years, Makemake 309.9 years and Eris 560.9 years.