Scientific proof that God exists,The Earth...its size is perfect. The Earth's size and corresponding gravity holds a thin layer of mostly nitrogen and oxygen gases, only extending about 50 miles above the Earth's surface. If Earth were smaller, an atmosphere would be impossible, like the planet Mercury. If Earth were larger, its atmosphere would contain free hydrogen, like Jupiter.Earth is the only known planet equipped with an atmosphere of the right mixture of gases to sustain plant, animal and human life.