How hot would the Sun be at different distances in the solar system?

Actually, the Sun stays the same temperature; about 5770 K. What you want is the temperature of some object at different distances. For example, the surface of a planet. This can be found using the formula:

Temperature  =   ( (1-A) x 1.4x10^6/(2.2x10^-4 x  r^r))^1/4
where A is the reflectivity of the surface and r is the distance to the Sun in 
Astronomical Units. Here are some typical values using the reflectivity of
each planet:
Planet........Distance.......Temperature

Mercury         0.4            450 K
Venus           0.75           235
Earth           1.00           240 
Mars            1.5            220 
Jupiter         5.0            100 
Saturn          10              75
Uranus          20              50
Neptune         30              40
Pluto           40              40

Of course, if the planet has an atmosphere, its actual surface temperature
will be somewhat higher due to the greenhouse effect.
 

Copyright 1997  Dr. Sten Odenwald
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