How fast does the Earth rotate?
Short answer: Approximately 1,675 km/h (1,040 mph) at the equator, slightly less near the poles.
Long answer:
The Earth is rotating on its axis at about 1,674.4 km/h (1,040.4 mph), as measured at the equator. This is 465.1 metres per second (1,526 ft/s). One complete rotation is called a day.
The rotational speed decreases as you get nearer either of the poles (see below).
How fast does the Earth spin where I live?
You can calculate approximately how fast the Earth spins at your location by using the following formula:
Speed at the equator (1,674.4 km/h or 1,040.4 mph) multiplied by the cosine of the latitude
Note: Arguments for the trig functions are in terms of degrees, not radians.
Examples:
- Te Awamutu Space Centre is located at latitude 38°S.
- cos(38) = 0.788
- 1,674.4 km/h x 0.788 =1,319.4 km/h
- Barrow, Alaska is located at latitude 71°N
- cos(71) = 0.32556815
- 1,040.4 mph x 0.32556815 = 338.7 mph
More information:
- Earth rotates towards the east.
- Viewed from above Earth's North Pole, it rotates counter-clockwise.
- Earth orbits the Sun at about 108,000 km/h (70,000 mph).
- Earth's rotation is slowing down by about 2.3 milliseconds per century. This means our days are getting longer.
- Belief that the Earth is a rotating globe dates back to ancient Greece, with members of the Pythagorean school accepting the rotating Earth model. However, Aristotle's view that the Earth is stationary was more popular. Despite the attempts of various astronomers to support the rotating Earth model, it was not until the Copernican revolution (16th/17th Centuries) that the rotating Earth model became the dominant theory.