It’s been studied somewhat, at least with satellites: > Assuming a dish antenna with 1-m diameter, for a downward-looking antenna the total noise temperature i

It’s been studied somewhat, at least with satellites: > Assuming a dish antenna with 1-m diameter, for a downward-looking antenna the total noise temperature is about the same as the Earth’s for all frequency bands of interest, with ±15 percent deviations. For an upward-looking antenna, the noise temperature is less than half that of Earth. [1] [1] https://ipnpr.jpl.nasa.gov/2000-2009/progress_report/42-149/149C.pdf https://ipnpr.jpl.nasa.gov/2000-2009/progress_report/42-149/...