Different points in the earth are at slightly different distances from the sun and hence experience different forces due to gravitation. For a rigid body, we know that if various forces act at various points in it, the resultant motion is as if a net force acts on the centre of mass causing translation and net torque at the centre of mass causing rotation around an axis through the CM. For the earth-sun system (approximating the earth as a uniform density sphere):
| 1. | the torque is zero. |
| 2. | the torque causes the earth to spin. |
| 3. | the rigid body result is not applicable since the earth is not even approximately a rigid body. |
| 4. | the torque causes the earth to move around the sun. |
