Dwarf Pluto

Comparing Pluto's size to Earth's size (as if they were placed side by side) Image credit: NASA

We have eight planets. Pluto is called a dwarf planet. Some scientists think that dwarf planets aren't really planets at all, even though the word "planet" is part of their name. Planets and dwarf planets are two separate groups.

So what is a dwarf planet? It is a round body that orbits the sun. It is not a moon. It has not cleared its orbital path of "junk." Dwarf planets are so small they don't have enough gravity to sweep up the other bits of matter within their orbits. Earth has thirteen times more gravity than Pluto does.

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