How can you tell if an animal is growing?

Why the moon is not visible from earth during the new moon ?

If we represent the solar system on a scale that allows us to walk from the sun to pluto in a few minutes, then a) the planets are microscopic and the stars are millions of miles away. b) the planets are the size of basketballs and the nearest stars are a few miles away. c) the planets are marble size or smaller and the nearest stars are thousands of miles away.

Based on current rates the earths human population is expected to grow how much by 2050