The Earth, since its birth four and a half billion years ago, rotates on its own axis, making a complete rotation in practically 24 hours (23 hours and 56 minutes to be exact). During that time, it also completes a longer orbit around the sun, which it does every 12 months. The Earth rotates on its axis at a speed ranging from o km/h to a maximum of 1,600 km/h above the equator, depending on the latitude. For example, at our latitude, it rotates at a speed of 1,180 km/h, although we are not aware of it, since we are rotating at the same time as the Earth. We are all moving with the earth at 800 mph eastward.
If the Earth stopped and we didn’t have our seat belts fastened to the Earth, we would fall off and spin at a speed of 800 miles per hour towards the east», declared the scientist Neil de Grasse Tyson on the American program ‘Larry King Now’. Let’s remember that 800 miles per hour is equivalent to 1287.48 km/h, an enormous speed.
The first thing that would suffer abrupt changes would be the atmospheric patterns, as well as the way in which air currents move, which play a fundamental role in controlling rainfall and temperatures; another consequence could be the appearance of deserts where there used to be forests or the transformation of frozen tundras into cozy and habitable places; also, another catastrophic consequence would affect the Earth’s core, which is partially composed of molten iron. The moment the Earth stopped rotating on itself, the magnetic field generated by the magnetic dipole produced by the mass of molten iron in the Earth’s core would cease to exist. The protective shield (geomagnetic field) against the harmful radiations produced by the sun and cosmic rays would also disappear.
The only thing that could suddenly stop or, better said, slow down the movement of the Earth would be the collision with another planet since in space there is no air or other particles that could stop that movement; however in the last years the Earth has slowed down and the Moon could play an important role in this event. According to scientists, «The motion of the side of the Earth that faces the Moon is not perfectly in balance with gravity, much less the side that does not face the Moon. This imbalance produces ocean tides, which cause the seas to rise or fall depending on the side of the Earth.» During the Earth’s rotation, the movements caused by the tides move across the surface of the planet in the form of a wave. This motion translates into a force that goes in the opposite direction of the Earth’s motion, gradually slowing down the planet’s rotation period. This results in the variation, every 50,000 years, of about one second in the total length of an Earth day.
More informations: Space.com: NASA, Space Exploration and Astronomy News