# Earth's Rotation How Earth's daily spin makes the Sun rise and set, why a day is almost 24 hours, and why the stars seem to circle the North Star\. By quiet\-wombat\-2b5f2b2e Topic: Earth & Geography [Open the interactive Jig](https://ask.jig.com/j/NbZG74Tjgox6) ## Transcript ### 1. A world that spins Right now you are riding on a spinning planet\. Earth turns all the way round once a day, and it never stops\. Drag the globe sideways to spin it yourself, or drag the sky to look around\. This globe is a model\. The real Earth is about 12,700 kilometres across\. ### 2. The invisible axis Earth spins around an imaginary line called its axis\. The axis runs through the North Pole and the South Pole\. It leans over by about 23 degrees, and its top points almost exactly at one star: Polaris, the North Star\. Because the axis keeps pointing the same way, the North Star seems to stay still while the other stars wheel around it\. ### 3. Turning toward the east Looking down on the North Pole, Earth turns anticlockwise, from west to east\. The glowing arrows show the ground travelling east around the pole\. As we turn east, the Sun seems to rise in the east and set in the west\. The Sun is not really moving across the sky\. Our horizon is turning toward it and then away from it\. ### 4. Day and night Only half of Earth faces the Sun at a time\. That half has day and the other half has night\. Slide the time and watch the glowing pin travel from sunrise, through midday, to sunset and into the night\. Earth turns 15 degrees every hour, so time zones are about 15 degrees wide\. The faint lines mark them\. ### 5. One turn, almost 24 hours Measured against the far\-away stars, one full turn takes 23 hours and 56 minutes\. Press the button to turn Earth exactly once and watch the pin come back to where it started\. We still get a 24\-hour day, because Earth also moves a little along its path around the Sun\. That extra bit of travel means Earth must turn about four more minutes before the Sun is back in the same place in your sky\. ### 6. Fast in the middle, slow at the poles Every place on Earth makes one trip around in a day, but the trips are different sizes\. A spot on the equator, the line around Earth's middle, travels about 1,670 kilometres per hour\. Halfway to the pole it is about 1,180, and at the poles you would simply turn on the spot\. Watch the three beads: they all finish their circles at the same moment, so the bead on the biggest circle must go fastest\. ### 7. Why we do not feel it We are moving fast, yet everything feels still\. The spin is smooth and steady, and the air, the oceans and you all travel along with the ground\. It is like sitting in a smooth plane: you only feel speeding up or slowing down\. The spin makes you lighter by only about a third of one percent at the equator, far too little to notice\. ### 8. Proof in the stars Press the button to open a camera shutter for six hours of night\. The camera rides on the turning Earth, so every star draws a curved trail\. The trails circle the point in the sky that lines up with Earth's axis, because it is we who are turning, not the stars\. A swinging pendulum can show the spin too\. The Foucault pendulum slowly turns its swing as Earth turns beneath it\. ### 9. Still turning Earth has been spinning for billions of years, and it is very slowly slowing down\. The Moon's pull on the oceans acts like a gentle brake\. Even while you sit still reading this, you are travelling east: at the equator, about 28 kilometres every minute\. Days grow longer by about 1\.7 thousandths of a second every hundred years\.