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Brady Yoon
2004-Apr-23, 11:21 PM
Could the greenhouse effect be so strong that a planet (such as Venus) could become entirely molten?

Ut
2004-Apr-24, 01:38 AM
I'm pretty sure the answer is 'no'. A planet massive enough to hold such an atmosphere would also be massive enough to keep a solid core.

Kaptain K
2004-Apr-24, 10:04 AM
By"completely molten", do you mean through and through or just the surface?

Brady Yoon
2004-Apr-25, 06:37 PM
By"completely molten", do you mean through and through or just the surface?

The entire planet.

bobjohnston
2004-Apr-25, 07:19 PM
I'd go with Ut on this one, pretty sure the answer is no.

The radiation a planet absorbs from the Sun must balance what the planet emits as blackbody radiation. Greenhouse gases serve to block certain bands of this outgoing radiation. Consequently, the planet's temperature must be higher to compensate, so it gives off more blackbody radiation outside these bands.

This cannot produce unlimited warming: heat the planet enough and the greenhouse gas absorption won't be at the right wavelengths to produce substantially more warming, I'd think.

umop ap!sdn
2004-Apr-26, 06:10 AM
heat the planet enough and the greenhouse gas absorption won't be at the right wavelengths to produce substantially more warming, I'd think.

Especially at the wavelengths molten lava emits. :o :P

bobjohnston
2004-Apr-26, 03:42 PM
Especially at the wavelengths molten lava emits.

Bingo!