why is pluto not considerd as planet
Pluto was discovered in 1930 by an astronomer from the United States. An astronomer is a person who studies stars and other objects in space.
Pluto was known as the smallest planet in the solar system and the ninth planet from the sun.
Today, Pluto is called a “dwarf / baby planet.” A dwarf planet orbits the sun just like other planets, but it is smaller. A dwarf planet is so small it cannot clear other objects out of its path.
On a regular bases, Pluto is more than 3.6 billion miles (5.8 billion kilometers) away from the sun. That is about 40 times as far from the sun as Earth. Pluto orbits the sun in an oval like a racetrack. Because of its oval orbit, Pluto is
why is it a dwarf
is now the largest known dwarf planet in the solar system. It is also one of the largest known members of the Kuiper Belt, a shadowy disklike zone beyond the orbit of Neptune thought to be populated by hundreds of thousands of rocky, icy bodies - See more at: http://www.space.com/43-pluto-the-ninth-planet-that-was-a-dwarf.html#sthash.LyOmW6Qi.dpuf
Pluto has a mean radius that is 20 percent smaller than Earth's at 715 miles. Unlike many planets in the solar system, Pluto does not bulge at the center. Instead, its radius is the same at the center as it is at its poles and equator. Pluto has a diameter of 1,430 miles, making it even smaller than the moon. Pluto's surface is composed of rock and ice.
why so cold
Pluto is cold because it is, on average, 3.6 billion miles away from the sun. The sun provides heat and energy to the entire solar system, and the farther away planets are from the sun, the colder they are.