The video is a discussion on the importance of Earth's rotation and the potential consequences if it were to suddenly stop. The presenter, Michael, explains that at the equator, the Earth's surface is spinning at 465 meters per second. As one moves away from the equator towards the poles, the speed of rotation decreases. This is because the centrifugal force required to keep the surface spinning decreases as well.
If the Earth were to stop spinning, everything not attached to it would be flung eastwards at over a thousand miles per hour. The atmosphere would gradually slow down, potentially allowing people in airplanes to survive. However, the initial impact would be catastrophic, with massive fires, unprecedented erosion, and damage to strong structures. The Sun would appear to freeze in the sky as days become 365 days long, and there would be a sudden influx of ionizing radiation from the Sun due to the disappearance of Earth's magnetic field.
The oceans would surge onto land in tsunamis, washing over nearly all dry land. Over time, the Earth would slowly compress into a more perfect sphere, possibly allowing the oceans to eventually return. The presenter concludes by noting that Earth's rotation is indeed slowing down, but the changes are so gradual that they are not immediately noticeable.
He also explains the concept of time, stating that a second is defined by the oscillations of an atom of cesium-133. This is how atomic clocks work and provides the most accurate measurement of time. However, the Earth's rotation can cause slight irregularities in the length of a day, which scientists keep track of using atomic clocks and other measurements. Over time, these slight changes add up to the need for leap seconds, which are adjustments made to the time system to keep it accurate.
Here are the key facts extracted from the text:
1. The Earth's surface at the equator is spinning at 465 meters per second.
2. As you move closer to the poles, the speed of the Earth's rotation decreases.
3. In San Francisco, the Earth is moving at 368 meters per second.
4. If the Earth suddenly stopped spinning, objects not attached to the Earth would continue moving and be flung east at over 1,000 miles per hour.
5. Escape velocity from the Earth is 24,800 mph.
6. If the Earth stopped spinning, the atmosphere would slowly come to a stop, causing massive storms and fires.
7. The Sun would appear to be frozen in the sky, and days would become 365 days long.
8. The Earth's magnetic field would cease to exist, exposing the planet to deadly amounts of ionizing radiation from the Sun.
9. The oceans would surge onto land in tsunamis, eventually migrating to the poles where gravity is stronger.
10. The Earth's rotation causes a bulge at the equator, which would disappear if the planet stopped spinning.
11. The Earth's rotation is slowing down due to changes in the distribution of mass on the planet and the effects of tides caused by the Moon.
12. In 140 million years, a day on Earth will be 25 hours long, not 24.
13. Atomic clocks measure time by counting the oscillations of the outermost electron of an atom of cesium-133.
14. One second is defined as 9,192,631,770 oscillations of the outermost electron of an atom of cesium-133.
15. The timekeeping device used to measure time is not based on the Earth's rotation, but on atomic clocks, known as TAI time.
16. To account for the Earth's slowing rotation, a leap second is added or subtracted from the current year every few months.
17. Since 1972, 25 leap seconds have been added to the current year.
18. The time used almost everywhere, including on phones, is called UTC time, which is a manufactured product that requires periodic updates.