To truly understand day and night, consider what wouldn’t happen.

The sun hasn’t set. The Earth has simply turned its shoulder.

The Earth orbits the Sun, a massive ball of hot, glowing gas, at an average distance of about 93 million miles (149.6 million kilometers). The Earth's position in the solar system is crucial in determining the amount of sunlight it receives. The Sun's rays travel through space and strike the Earth, illuminating its surface.

For most of human history, we had it backwards. Ancient Egyptians believed the sky goddess Nut swallowed the sun each evening, only to give birth to it again at dawn. The Greeks thought Helios drove his fiery chariot across the sky, then sailed around the Earth in a golden bowl at night.