the planets

[bobtheduck]

does jupiter and saturn etc have a surface? or are they just gas

[kags]

They are gas, but some experts believe they may have a rocky inner core - how we ever discover this is another matter!

[bernardo]

They are so big and heavy that the internal pressure must have squashed the gas into a liquid blob, and in the middle an iron core

[IggyB]

if they're just gas why do we call them planets instead of clouds?

[Moog]

A planet is loosely defined as: A spherical ball of rock and/or gas that orbits a star, which is why there is much discussion over whether bodies such as pluto is a planet (with it not being spherical). If you take surface to be defined as: the outer boundary of an artifact the yes the gas giants do have a surface, but if you're thinking of is in terms of a "solid" surface on which humans could maybe stand then it's not sure. Jupiter has an extremely low density so it's thought unlikely that any part of it is solid or possibly liquid and the same is true of Saturn which is believed to have a liquid core but no destinct surface, but instead a gradual transition from gas to liquid.

[bernardo]

IggyB - they'd be pretty silly clouds if they're spherical. Clouds would be more blobby-shaped.