What is the EM spectrum of the earth seen by a satellite?

Question

I am asking because of the greenhouse effect. It is said that without the atmosphere, the average surface temperatur of the earth would be about -18 celcius. This number is obtained simply by assuming that the earth is a blackbody and balancing the incoming energy from the sun and the outgoing energy from the earth.

Now this argument should always hold, if the assumption of the earth as a blackbody is right. The question is then, what is the EM spectrum of the earth seen from a satellite or from a guy on the moon? Does it correspond to a blackbody at the temperature of -18 celcius?

Of course, much of the sunlight is reflected by the earth, so we have to subtract this part from the spectrum.

Answer 1

The spectrometer or imager will see the radiation from the surface of the earth, but will have absorption bands in the spectrum. e.g. from Understanding spectra from the earth So if you image or measure the spectra from a hot part of the earth, or a cold part of the earth you will have a different "temperature".

So that is treating the Earth as a radiator, which if you are in the shadow of the earth is o.k. You have a different set of issues if you are imaging where the sunlight is hitting the earth. You still have the infrared emission from the earth, but you also have the reflection of sunlight where those wavelengths are mostly in the visible range.