Ten Things You Don't Know About Pluto

[ILLigitt]

10) It's called an ice world but it's almost 70% rock on the inside.

We know Pluto is icy because we have been able to determine its surface composition -- taking spectra (breaking up the light into colors like a rainbow) of an object can tell you what types of materials are present. We also know Pluto's size and mass, so we can tell how dense it is (which is its mass divided by its volume).

Surprisingly -- at least to me, because I didn't know this until Alan Stern told me -- Pluto has a density of about 2 grams/cubic centimeter, which is roughly the density of rock. But ice has a density of less than 1 gm/cc! Since the surface is icy, that means Pluto's interior must be loaded with rock. Studies show that this must be true, and in fact it must be rockier in general than even some of the moons much closer to the Sun like Ganymede and Titan.

Pluto's surface is different than its interior, meaning at some point in its past it must have been at least partially liquid. Light things float and dense things sink, so the rocky stuff sank to the interior, while the lighter stuff like nitrogen and methane came to the surface. Moreover, there must be methane trapped underneath its surface! Every 250 years, when Pluto approaches the Sun, the methane on its surface goes straight from solid to gas, and methane is so light that it can escape the planet. So there must be some source of methane under the surface, or else Pluto would have lost all its methane eons ago.

There's a lot more to Pluto than meets the eye. I'm glad we're sending a probe there. It's a strange little world, and we need to take a better look at it.

[sabrina]

I love Pluto. I refuse to stop calling it a planet. "Me too!" said RA

[Kaiser]

Originally Posted by sabrina

I love Pluto. I refuse to stop calling it a planet. "Me too!" said RA

Yes!

Pluto is the cutest little planet ever. The thought of it having its planethood taken from it actually makes me feel sorry for it.

Yes, I realise this is completely absurd. Screw you all, however.

[sabrina]

Originally Posted by Kaiser

Yes!

Pluto is the cutest little planet ever. The thought of it having its planethood taken from it actually makes me feel sorry for it.

Yes, I realise this is completely absurd. Screw you all, however.

Hahaha this was the cutest little post ever. Pluto thanks you, from the bottom of it's nearly forgotten little heart.

[dancebanana99]

that's really interesting information