21st Feb 2013

imagejonic replied to your link: Want to name the moons of Pluto?

Do they still count as moons if Pluto isn’t classed as a planet anymore? Genuine question, I’m curious :)

Yes they do! A moon is usually defined as a natural satellite that orbits a larger celestial body (which presumably is then orbiting the sun). Even asteroids have moons—in the 1990s, the asteroid 243 Ida was discovered to have a natural satellite, named Dactyl.

Pluto is a dwarf planet, and Hydra, Nix, and P4 and P5 are classed as its moons—but there’s some controversy surrounding Charon. Since it’s quite large, with a tenth of Pluto’s mass (compared to our moon being one eightieth of the Earth’s mass), the centre of mass of the Pluto-Charon system lies outside both celestial bodies, so they’re sort of orbiting each other. Charon could technically be referred to as a dwarf planet, and the Pluto-Charon system is sometimes called a binary planet!

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    More questions? No worries here’s an answer courtesy of science.
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  6. razzretina said: Binary planets?! I didn’t even think that could be a thing! How wonderful!
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  12. awaitinganadventure said: Why do some moons get “normal” sounding names and others get lettered and numbered?