Somewhere in the neighborhood of 27-28 thousand miles. Is it getting bigger? No clue what someone else would say, but, I think I can prove it is getting bigger using one sperm and one egg (Human of course) Each one is nearly the size of a grain of sand. By the time you die, it will be a small handfull of dust. Multiply it by the billions of times this has happened, not just to humans, but all creatures great and small, and, can't forget the plants. Further, the planet has been subjected to bombardment from space, which adds more, rock by rock.