Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Pseudoscience-is-malarkey on 28/08/2022 14:26:54
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A sports commentator once referred to the Sun as his favorite planet, only to be interrupted by someone on his production crew to inform him that it's a star. If he was right, then we could all easily say that the Sun is the winner at a whopping 9940.73°F.
Yes, Venus's surface is hot at 900°F, which is even more than the sunny side of Mercury. But Jupiter's surface (its sea of metallic hydrogen) is about as hot as the surface of the Sun. The solid points on the other gas planets are also much-much hotter than Venus.
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Last time I checked (which was admittedly a while back), we weren't sure whether the gas giants had a solid surface of any kind. The cores might be fully molten.
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Last time I checked (which was admittedly a while back), we weren't sure whether the gas giants had a solid surface of any kind. The cores might be fully molten.
The 'surface' is where the atmosphere ends, not necessarily where the solid starts. The surface of Earth is mostly ocean (something molten), but that doesn't stop it from being the surface.
So PSiM actually has a point here. Why is the designation of 'surface' on a gas giant different than it is for other planets with atmospheres? It is admittedly inconsistent.
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For consistency, NASA publishes "surface" temperature as the mean of the solid surface temperature for the rocky planets, or the temperature at 1 bar for the gas giants, which corresponds to sea level on Earth.
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The 'surface' is where the atmosphere ends, not necessarily where the solid starts.
That's not well-defined for a gas giant, though. As you go deeper into the atmosphere, the pressure and temperature increases until you go from a gas to a supercritical fluid (which has characteristics intermediate between that of a gas and a liquid).
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And as you go deeper this superfluid reaches pressures where it starts to exhibit properties like a massive crystal, yet it is still not a solid, as the atoms do still flow around.