A useful rule of thumb is, all other things being equal, thermal gradient scales as for gravity (it's a mathematical function of included mass, divided by surface area).
So, if the Moon had the same composition of the earth, it would have 1/6 the thermal gradient.
Instead of ~30 K/km, it would be 5 K/km, and the temperature at 8 km (5 miles - get with the metric system), would be 40 K hotter than at the surface.
You can do the maths on other objects but beware the composition assumption. We KNOW it isn't true for our own Moon, due to it's very small core.
The Moon is depleted by about 50% compared to earth in K, and by about 10% in U and Th, the major heat-producing radiogenic elements, therefore it should be even cooler than the simple assumption...
Space/Science » in reply to re: 10 things about planets
Thermal gradients