The two motion of the earth are :
1. Rotation or the daily motion and,
2. Revolution or the annual motion.
Rotation :
The earth rotates (turns) round its axis from west to east once in twenty four hours. This motion is called the Daily Motion or Rotation. This rotation of the earth is the real cause of the apparent rising and setting of the sun which is stationary.
Its effects :
1. Day and night’s are caused. This is by far the most important effect of rotation.
2. The sun, the moon and the star appear to revolve round the earth from east to west.
3. Winds and currents changes their direction.
4. Different places have different local times.
5. Tides occur regularly twice a day.
Revolution :
The earth revolves round the Sun once approximately 365 – 1/4 days. This motion of the earth round the Sun is called Revolution. The earth revolves round the sun in a fixed path at a speed of 29.8 km/sec. or 107,2000 km. per hour. This path is called the orbit of the earth. The earth’s orbit round the Sun cover a distance of about 965 million km. Its effects :
1. This motion of the earth is one of the cause of the seasons.
2. Days and nights are of unequal length at the same place.
3. Change in the altitude of midday Sun during the year.
