During the day the sun can be seen in the sky, while at night the moon, planets, and stars are visible. Stars produce their own light, while planets and satellites orbit other celestial bodies without producing their own light. The solar system includes the sun and objects that orbit it, such as planets, comets, and asteroids. The moon orbits the earth every 28 days, causing its phases to change. The earth's orbit around the sun causes the seasons, and its rotation on its axis causes day and night.
