<P> Earth's rotation is the rotation of Planet Earth around its own axis . Earth rotates eastward, in prograde motion . As viewed from the north pole star Polaris, Earth turns counter clockwise . </P> <P> The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where Earth's axis of rotation meets its surface . This point is distinct from Earth's North Magnetic Pole . The South Pole is the other point where Earth's axis of rotation intersects its surface, in Antarctica . </P> <P> Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to the stars (see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past . This is due to the tidal effects the Moon has on Earth's rotation . Atomic clocks show that a modern day is longer by about 1.7 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap seconds . Analysis of historical astronomical records shows a slowing trend of about 2.3 milliseconds per century since the 8th century BCE . </P> <P> Among the ancient Greeks, several of the Pythagorean school believed in the rotation of the earth rather than the apparent diurnal rotation of the heavens . Perhaps the first was Philolaus (470--385 BCE), though his system was complicated, including a counter-earth rotating daily about a central fire . </P>

Who discovered the earth rotates on its axis