地球為什麼會自轉 。why does the earth rotate?（５點）

Orbit and rotation
Main article: Earth's rotation

An animation showing the rotation of the Earth.Relative to the background stars, it takes the Earth, on average, 23 hours, 56 minutes and 4.091 seconds (one sidereal day) to rotate around the axis that connects the north and the south poles.[79] From Earth, the main apparent motion of celestial bodies in the sky (except that of meteors within the atmosphere and low-orbiting satellites) is to the west at a rate of 15°/h = 15'/min. This is equivalent to an apparent diameter of the Sun or Moon every two minutes. (The apparent sizes of the Sun and the Moon are approximately the same.)

Earth orbits the Sun at an average distance of about 150 million kilometers (93.2 million miles) every 365.2564 mean solar days (1 sidereal year). From Earth, this gives an apparent movement of the Sun with respect to the stars at a rate of about 1°/day (or a Sun or Moon diameter every 12 hours) eastward. Because of this motion, on average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of the Earth averages about 30 km/s (108,000 km/h or 67,000 mi/h), which is fast enough to cover the planet's diameter (about 12,600 km [7,800 mi]) in seven minutes, and the distance to the Moon (384,000 km or 238,000 mi) in four hours.[65]

因為地球有日和夜.

因為冇人阻住