Isn't saying "Pluto and Charon are totally different" the same as saying "Earth and its Moon are totally different"?
Interestingly enough, the earth and moon are very similar in composition. They are made out of the same stuff, the isotope ratios of the elements in their crusts are nearly identical and the internal structures are similar. The difference is that the earth was big enough to keep its atmosphere, have tectonic activity and generate a magnetic field. The moon is about 1/4 the size of the earth and about 10% of its mass, so it cooled faster, lost its air and magnetic field (if it had one).
Pluto and Charon, if they slit from an impact, should be similar as well, yet their surfaces are weirdly different. The next few weeks are going to give us a great look at a place in the universe that we have never seen up close before. New Horizons is already rewriting the books on Pluto.
Thank you for this explanation. Very clear and made the difference more reasonable :)
I think what they mean is that Pluto and Charon could have very different compositions, while the Earth and the Moon are nearly the same composition.
Many people saying Pluto is not a planet, and the two might orbit around each other.