Rotation
Rotation is the spinning of a body around its own axis; Earth rotates once every 24 hours, which produces day and night.
Definition
Rotation is when an object spins around an imaginary line through its middle called an axis, and Earth rotates once every $24$ hours, which is why we have day and night. Earth turns from west to east once every $24$ hours relative to the Sun, causing the daily cycle and the apparent motion of the Sun, Moon, and stars across the sky from east to west; every planet rotates, but at different rates and, in a few cases, in different directions. Earth's sidereal rotation period, measured against the stars, is $23$ hours $56$ minutes $4$ seconds; the solar day of $24$ hours is longer because Earth also advances about $1^\circ$ along its orbit each day and must turn slightly more to face the Sun again. Rotation produces the Coriolis effect, which deflects winds and ocean currents and organizes weather into rotating systems, and it flattens Earth into an oblate spheroid with an equatorial radius about $21\ \text{km}$ larger than the polar radius. Tidal friction with the Moon slows the rotation by about $2$ milliseconds per century.
Example
As Earth rotates toward the east, the Sun seems to rise in the east and set in the west, though really the Sun is staying put and we are turning. Jupiter rotates once in just under $10$ hours, the fastest of the planets, while Venus takes $243$ Earth days to rotate once and spins in the opposite direction, so on Venus the Sun rises in the west. Earth's equatorial rotation speed is the circumference divided by the sidereal period: $40{,}075\ \text{km} / 23.93\ \text{h} \approx 1{,}670\ \text{km/h}$. At Charlotte's latitude of $35^\circ$, the speed is $1{,}670 \times \cos 35^\circ \approx 1{,}370\ \text{km/h}$.
Key Insight
Even though Earth spins at about $1{,}600$ kilometers per hour at the equator, we do not feel it because everything around us, including the air, is moving along with us. Rotation does not cause the seasons and it does not cause the Moon's phases; it causes only the daily cycle of sunrise, sunset, and the stars wheeling overhead. Foucault's pendulum, first shown in 1851, provided the first direct laboratory proof of Earth's rotation, since the pendulum's swing plane appears to turn as the ground rotates beneath it. Growth rings in fossil corals confirm that days were shorter in the past, about $22$ hours $400$ million years ago.