" writes:

sorry if this is a repeat post...

How hot would a nearly ideal black body object get in Mercury orbit?

I've read that Mercury's daytime temperatures can spike to 800F, but my
calculation for average temperatures at Mercury orbit was 440K/328F.
Mike Miller, Materials Engineer

Your calculations are about right for a spherical black body at Mercury's
distance from the sun.

A flat plate at the same distance, front face painted black and pointed
at the sun, back face coated with an ideal insulator, will reach 640K
or 700F. Same heat input, less surface area for radiant heat output.

As Mercury doesn't have an atmosphere or an ocean to complicate things,
we might reasonably conclude that the *average* temperature on Mercury
would be somewhere around 440K and the *maximum* temperature would be
more like 640K. On an equatorial plain of loose, dark regolith at local
noon.


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