I assume it is the make up of the Earth that provides it with enough gravity to keep it the same distance from the sun. Has it moved any nearer, or further away and what will happen if it does. If my assumption is correct then I also assume that as the Earth's resources are used up, that gravitation will change, which could not only affect our distance from the Sun but also the distance the moon is from us.
Now, given that for billions of years not a great lot of resource was taken from the Earth, that could explain why the distances may not have changed significantly. But, at the rate resources are now being used, could that change? I suppose it's possible the Sun could cool down and fizzle out first and there's not much we could do about that. One way or another, in time, I suspect we will either find ourselves hurtling towards the Sun (say goodnight quickly) or drifting away from it and freeze. What happy thoughts