Why does Earth rotate
Looking at the contrary gives birth to many bewildering possibilities, and there is no better example of this theory than the rotation of the Earth. Take the rotation out of the equation and we stare at a day spanning over an year. Had the Earth maintained the same orientation towards the Sun, half of the planet would have been burnt in the seething sunlight, and the remaining half would have been laid to sleep in a blanket of snow and ice.
Thankfully, the Earth rotates, and we do not have to face either of these two equally deplorable situations. Inquisitive minds have always looked towards astronomers to explain the rotation of the Earth and the other planets. Astronomers propose that millions of years ago, a supernova sent shockwaves through a cold cloud of molecular hydrogen. The molecular chunks thus created had their characteristic momentum, which got added when they conglomerated to form even bigger chunks. The law of conservation of momentum comes into play from here on and it is anybody’s guess that the next tenet of this theory would state that the solar nebula was set into spinning in this form. Over the course of time, the planets gained proximity to each other, courtesy the undeniable effects of gravity. Particles with momentum kept on impinging on the planetary surfaces, thus making the planets even bulkier. This also led to the additional momentum gains of the planets. The departures from uniformity are explained through chance events of collisions.
A massive collision is believed to have inversed the rotational behavior of Venus, and the 23 degree tilt of the Earth’s axis is also attributed to a collision. We all observe that a top spins for quit some time, because of the fact that the frictional forces take some time to overcome the free rotation of the top. However, the Earth faces negligible friction during its rotation, which obviously means that its naturally acquired rotation is expected to continue unabated. This is because the playground for the Earth, and all the other planets, is the solar space, which is sans any vacuum.