The dinosaur days were 30 minutes shorter

In the era of dinosaurs, the earth rotated faster than today - then the day lasted only 23.31 hours, as evidenced by the growth of rings in the shells of fossil mussels. As a result, 70 million years ago, the year was 372 days instead of 365. The reason for this is the Moon, which over time slows down the rotation of our planet more and more. The chalk shell now helps restore this effect in the past.

Our days today have 24 hours, this period of time corresponds to the rotation of our planet around itself. But in the course of the history of the Earth, the rotation of the Earth has changed - and this is still happening. As the Earth’s rotation gradually slows down, our days are lengthening by about 1.78 milliseconds per century. This is one of the reasons why an extra second is added in certain years, as was the last time in 2016.

In addition to earthquakes, processes in the earth’s core and melting ice, the slowdown of the Earth’s rotation is mainly due to the tidal forces between the Earth and the Moon: since both celestial bodies act on each other with their gravitational force, the Moon has an inhibitory effect on the Earth’s rotation. As a result, the moon itself accelerates in its orbit and thus moves 3.82 centimeters farther from the earth every year.

It is not clear, however, how the earth-lunar system and the Earth's daily extent evolved in the past. After all, the interaction of both of these and the drift of the Moon does not go linearly - if that were the case, the Moon would have to lie 1.4 billion years ago in the bowels of the Earth. Therefore, researchers rely on models and fossil evidence to reconstruct the length of the day of past centuries.

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