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Pluto used to be the smallest planet in the Solar System, but now it isn’t a planet any more, thanks to a recent decision from the International Astronomical Union. But now it’s one of the largest dwarf planets, so that’s a good thing. How big is Pluto?
The diameter of Pluto is only 2,390 km across. Just for comparison, that’s about 70% the diameter of the Moon. And it’s a fraction of the size of the Earth; about 18% of the Earth’s diameter.
In terms of volume, Pluto only has 6.39 x 109 km3. That sounds like a huge number, but it’s only 0.59% of the volume of the Earth. In other words, you could put almost 170 objects the size of Pluto inside the Earth.
The mass of Pluto is 1.3 x 1022 kg, which is only 0.2% the mass of the Earth, or 18% the mass of the Moon. Needless to say, Pluto doesn’t have very much mass at all.
The surface area of Pluto is 1.67 x 107 square kilometers. That’s only 3.3% the surface area of Earth, and about the same surface area as Russia.
If you could stand on the surface of Pluto, you would experience only 6.7% the gravity you enjoy on Earth.
We’ve recorded an entire episode of Astronomy Cast about Pluto and the rest of the icy outer Solar System. You can find it here.