The radius of the Earth is 6378 kilometers and its circumference is 40,066 kilometers so that in 24 hours it rotates at 40,066/24 = 1669 kilometers/hour. The speed at the surface changes with latitude according to the 'cosine' of the latitude so that at latitudes of 45 degrees, the speed is 1669cos(45) = 1179 kilometers/hour, and within 1 mile of the north or south pole, at a latitude of 89.98 degrees, the speed is 1669cos(89.98) = 0.4 kilometers/hour.