# Heat reflection on distant planets

I was watching a documentary last night on the first planet discovered outside our solar system.

The first one apparently is a giant gas planet that orbits very close to its sun over a very fast period (~1 week per orbit), and it's so hot all metal elements vaporise and form parts of it's atmosphere (so the current theory states anyway).

Out of curiosity, when they estimate the surface heat of the planet (they give big numbers), did they take into account reflection of heat from it's metallic atmosphere, and internal reflection from heat bouncing off the surface and it's atmosphere (like global warming) when estimating surface temperature of the planet?

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Thank you for your question. However you are asking for an explanation for a calculation of some publication I suppose. You might want to add a reference to it since otherwise people will have to speculate what was going on. Greets – Robert Filter Apr 19 '11 at 11:46
Don't they just take the temperature of the blackbody spectrum of the planet to be the temperature of the planet? If it radiates at temperature T, then there's no need to do any complicated modeling to figure out the temperature of the planet's atmosphere--it's a direct measurement. I assume this is also how they know that there are heavy elements in the planet's atmosphere, too. I don't know enough about this to know if they can resolve the planet's spectrum from the star's spectrum, though. – Jerry Schirmer Apr 19 '11 at 16:17
I would agree with Jerry, these are usually gas giants, so there is no well defined solid or liquid surface. The temperature would be at approximately a single optical depth (in the radiating frequencies at whatever the temperature is) down. As long as there is heat flux from deeper down, by absorption of radiation, or internal processes, including tidal effects, there will be a temperature gardient so the temperature at great depth is probably very high. – Omega Centauri Apr 19 '11 at 16:36

The temperature estimation procedure basically is to equate the star's incoming radiation to the planet's outgoing radiation. Factors like star type and distance, planetary albedo and greenhouse gases can be estimated. Here's a nice site with the necessary formulas, http://www.dangermouse.net/gurps/science/temps.html.

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