Why are there 24 hours in a day on Earth?

the University of Toronto Its researchers examined the factors that affect the speed of our planet’s rotation. concluded in their resultsthat in the period 2.2–0.6 billion years ago, this is due to the fixed length of days of 19.5 hours today no Our days are 60 hours.

The rotation of our planet’s axis is mostly influenced by the Moon. When the Moon formed, Earth’s days were only 10 hours long, but since then our companion’s gravity has slowed Earth’s rotation, so the days are getting longer and longer.

The length of days in the past and the tidal cycles can be examined in several ways, on the one hand by coastal sediment stratification, and on the other with the aid of the skeletons of many calcareous animals, or the growth strata of stromatolites built up by microbes.

We owe the braking effect to the tides. Under the influence of the moon, a bulge is formed in the oceans, which rotates around it and in the process stops the rotation of the planet. Of course, not only the Moon, but also the Sun affects the tidal conditions of our planet with its gravity, causing the atmosphere to bulge, but this has the opposite effect of the Moon: it speeds up the rotation of our axis. For most of our planet’s history, the tidal forces caused by the Moon exceeded the tidal forces of the Sun by ten times, which is why they constantly slow down the rotation of our axis and increase the length of days. However, approx. Two billion years ago, our atmosphere was much warmer, and because of this, the humps caused by the Sun were larger. In addition, the natural resonance of the atmosphere, that is, the frequency of the passing waves, was the same as the length of the days.

Our atmosphere rings like a bell, its frequency depends on various factors. Temperature is also an important part of these factors. This means that different waves, such as those from violent volcanic eruptions, travel through the atmosphere at different speeds, depending on its temperature. For the same reason, the sound of a bell is also the same if its temperature is constant.

For most of our planet’s history, this resonance was out of sync with the planet’s rotational speed, and they are still very different today. The day is 24 hours long, but the atmospheric tides, which are very small, go around the Earth in 22.8 hours. However, in a period of more than a billion years when our atmosphere was much warmer, the resonance was about 10 hours long, and by the beginning of this era the Moon was already approx. It has slowed the rotation of our planet’s axis by 20 hours. This caused the tides in the atmosphere and our rotation speed became synchronized, so the tides in the atmosphere became much larger, which was able to counteract the influence of the moon. In Hungary, during this period, the effect of the tides and the Sun has intensified due to the temperature of our atmosphere, while the temperature of the Moon has not changed, so they have balanced each other out. For this reason, the length of the days is almost the same for a long time. It was 19.5 hours.

This timing is like rocking a toddler. If I don’t push the swing in time, it won’t lift much. But if you push the swing at the right moment, it can go higher and higher.

According to the researchers’ model calculations, the current warming will not be without consequences. Of course, this won’t happen overnight, but with the fact that our atmosphere is now getting warmer, the resonance speed and shaft rotation speed will be less in sync. Because of this, the days are getting faster than they would be without climate change.