The Earth spins at about 1,674 kilometers per hour (or approximately 1,040 miles per hour) at the equator. This speed changes with latitude, being fastest at the equator and slowing to zero at the poles because the circumference of the rotating circle decreases from the equator to the poles. Earth completes one rotation roughly every 24 hours relative to the Sun, or every 23 hours, 56 minutes, and 4 seconds relative to distant stars, which is called a sidereal day. The angular speed of Earth's rotation is about 7.292×10−57.292\times 10^{-5}7.292×10−5 radians per second, which translates to the equatorial speed mentioned above based on Earth's radius. Earth’s speed of rotation varies slightly over time due to factors such as the movement of its molten core, oceans, atmosphere, and interactions with the Moon’s gravity. Recently, Earth's rotation has been speeding up slightly, shortening the length of days by around 1.6 milliseconds at times. To summarize:
- Earth's equatorial rotation speed: ~1,674 km/h (1,040 mph).
- Rotation period relative to the Sun: ~24 hours.
- Rotation period relative to stars (sidereal day): ~23h 56m 4s.
- Speed decreases as latitude approaches poles.
- Rotation speed fluctuates slightly due to natural Earth and celestial influences.
This speed is why we experience day and night but do not feel the spinning because the rotation is smooth and constant.
