How fast does the Earth rotate?

Earth rotates on its axis at approximately 1,670 km/h (1,037 mph) at the equator, decreasing to 0 km/h at the poles. One complete rotation takes 23 hours, 56 minutes, and 4.1 seconds — a sidereal day. The reason a solar day is ~24 hours is that Earth also moves along its orbit, requiring an extra ~4 minutes of rotation to face the Sun at the same position. Earth's rotation is gradually slowing due to tidal friction from the Moon, at a rate of about 2.3 milliseconds per century. Six hundred million years ago, a day was only about 21 hours long, and days will continue getting longer. If Earth suddenly stopped rotating, the atmosphere would continue moving at 1,670 km/h, creating catastrophic winds, and the oceans would shift toward the poles due to the loss of the equatorial bulge.