To find out how much warmer Callisto is than the dark side of the Moon, we need to subtract the average temperature of the Moon from the average temperature of Callisto.
The average temperature of Callisto is –139°C, and the average temperature on the dark side of the Moon is –184°C.
Calculating the difference:
\[ -139°C - (-184°C) = -139°C + 184°C = 45°C \]
So, Callisto is 45°C warmer than the dark side of the Moon.