Why does earth rotate?
It is believed that the earth is made up of cloud of gas and dust particles called nebula that collapses under its own gravity and started spinning. When this cloud and dust particle condensed they remained in rotation and the rotation is speeded up when condenses at the center. So it is said that earth had been rotating since it was formed but now the question arises that why doesnâ€™t it stops? It is because in our everyday life we see if we push an object it moves for sometimes and then stops and force is required to keep it moving but this assumption is wrong. Objects will keep on moving till another force is applied to stop it. When an object comes to rest after moving for a while, friction acts on it and it stops. Same is the case with earth. It is moving and remains spinning till the force is applied on it to stop.
Luhman saysâ€ the earth keeps spinning because it was born spinningâ€. He further says that the speed of rotation of earth is slowing down because of tidal pull by themoon. It is slowing at the rate of nearly one millisecond per year. He says that the length of days at the times of dinosaurs was 22 hours. Tidal pull of moon is also receding the moon at the rate of nearly one millimeter per year. Luhman says â€œit would have appeared much larger in our sky than it does nowâ€.
All planets rotate in same direction and in almost same plane.