What causes day and night? Why do we have seasons? Through easy-to-understand animations, as well as live-action video footage, these difficult concepts are easily explained. The rotation of earth on its axis, and its revolution around the sun are the focus of this program. Colorful graphics vividly illustrate the movement of our planet throughout the course of a year. Important terminology includes: axis, tilt, rotation, revolution, orbit, season, solstice. and equinox. .