foggy starts

this morning when we left for kinder it was 0 degrees and foggy. by the time i had got home the fog had cleared and there was just a
little in the low lying areas.
on the way to kinder the sun was behind the fog and it looked silver, like the moon.
Hugo: mummy is that the moon
Me: i think it is the sun beneath the fog, making it look like that.
Hugo: how does the sun stay up in the sky?
Me: well... what do you think?..............
Hugo: (a slight pause ) i think there might be a power switch that turns the heat and the light on in the sun. i don't know how it stays up there in the day but when it gets to night time there must be another switch that turns it off and puts it down. the switch would have to turn otherwise the sun would just drop and fall down and it goes slowly that's why the switch must turn so it can go down slowly.