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The White Dwarf that Shattered Asteroids and Earths
| posts about #whitedwarf more → |
The White Dwarf that Shattered Asteroids and Earths |
01/06/09
01/05/09
to me 'rocky inner planet' doesn't cut it...
thoughts?
01/06/09
Try the additional qualifier "Inhabitable" or "Rosie O'Donnell-free"
01/06/09
01/06/09
Terrestrials tend to be small, mostly rocky with dense metal cores. Jovians tend to be gas giants with very powerful magnetic fields. However since our discovery of extrasolar planets and since our exploration of all the jovian moons. There has been some discussion about adding two new categories:
1) Superjovians or substellars. These are gas giants that are much larger than Jupiter but are not quite large enough to ignite nuclear fusion. There is a lot of argument if brown dwarf stars aren't stars at all but merely superjovians.
2) Ice worlds. These are often moons and are mostly composed of ices with no metal cores. Many are large enough to be considered planets in their own right. Like Titan, Europa, Miranda, Charon, Pluto and so on.
But even these categories are not sharply defined. Io is an odd moon thanks to Jupiter's tidal forces, is it really an ice world? Earth's moon is unlikely to have a molten metal core so is it really a terrestrial? Is Pluto really a planet at all?
This is not mere hair splitting. Being able to classify planets properly tells us a lot about how planetary systems form in the first place.
01/06/09
we bemoan the fact that science literacy is declining and yet we are willing to describe a planet as "earth-like" when it's only simillarity to earth is that it's a rock in space.
01/05/09
01/06/09