H004
Is Earth’s spin carrying you at 1,000 mph?
It’s the speed everyone quotes for Earth’s rotation. How fast you’re really moving depends on where you’re standing.
How fast Earth’s spin carries you, by latitude
Speed around Earth’s axis while standing still on the ground
Every place makes one full turn in the same 23 hours 56 minutes. Near the poles, the circle is smaller.
Only near the equator. At 60° north the spin carries you half as fast, and at the North Pole it carries you nowhere at all. Every place on Earth turns once in the same 23 hours 56 minutes, but the farther you are from the equator, the smaller the circle you ride around the axis. Salt Lake City covers about 18,900 miles (30,300 km) a day; the equator covers 24,901 miles (40,075 km).
A single number for something that varies from place to place is usually the biggest case or an average, stated as if it applied everywhere. When you hear one, ask: where, and for whom?
Try it somewhere else
A car's window sticker says 30 mpg, a blend of a city test and a highway test.
Will your commute actually get 30 mpg, or does the number depend on where you drive?
Why don’t we feel it?
You, the ground, and the air around you all move together, so nothing rushes past you. People feel changes in motion, not steady speed, the same reason a drink stays put on a smooth flight. Earth’s spin does leave measurable traces, such as the Coriolis effect that steers large storms and ocean currents.
How the numbers are calculated
Treating Earth as a sphere, the circle you travel around the axis each turn is Earth’s equator, 24,901 miles (40,075 km), times the cosine of your latitude. Speed is that circle divided by one turn relative to the stars, 23 hours 56 minutes 4 seconds (23.9345 hours). The familiar 24-hour day is a little longer because Earth also moves along its orbit around the Sun.
| Place | Latitude | Circle per turn | Speed |
|---|---|---|---|
| Quito, Ecuador | 0° | 24,901 mi (40,075 km) | 1,040 mph (1,674 km/h) |
| Honolulu | 21.3° N | 23,200 mi (37,338 km) | 969 mph (1,560 km/h) |
| Houston | 29.8° N | 21,609 mi (34,776 km) | 903 mph (1,453 km/h) |
| Salt Lake City | 40.8° N | 18,850 mi (30,337 km) | 788 mph (1,267 km/h) |
| London | 51.5° N | 15,502 mi (24,947 km) | 648 mph (1,042 km/h) |
| Oslo | 59.9° N | 12,488 mi (20,098 km) | 522 mph (840 km/h) |
| Svalbard | 78.2° N | 5,092 mi (8,195 km) | 213 mph (342 km/h) |
| North Pole | 90° N | 0 | 0 |
The same speeds apply at the matching southern latitudes. Values are rounded and ignore Earth’s slight flattening and your altitude. They measure motion around Earth’s axis only; Earth’s trip around the Sun and the Sun’s trip around the galaxy are far faster.
Related exhibits
Sources: NASA Imagine the Universe, “Ask an Astrophysicist: Earth’s rotation” (equatorial circumference and the latitude formula); NASA Science, Basics of Space Flight, chapter 2 (sidereal and solar day). Speeds calculated for a spherical Earth and rounded; city latitudes are approximate.