Earth slowed down dramatically during worst ever mass extinction, Chinese-led study finds
- Two major shifts in the speed the world spins round were found – one during the Great Dying and the other during a sudden explosion of life
The speed at which the world spins round slowed dramatically twice hundreds of millions of years ago, with one time coinciding with the biggest mass extinction event, according to new research.
The other incident happened during a rapid expansion of life on Earth known as the Cambrian explosion, the Chinese-led team concluded.
Although the world seems to rotate at a constant pace, the exact timing can vary and is not precisely 24 hours.
Changes in gravity caused by variations in the distance between the moon and the Earth are known to cause ocean tides, but the friction between the tides and the Earth’s surface also causes a slight deceleration in its rotation. At the same time, Earth transfers momentum to the moon, causing it to gradually move outward.
According to the study, the Earth’s rotation has been decelerating due to this phenomenon throughout its history but this rate has varied over time.
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After two years of analysis the team, led by Ma Chao from the Institute of Sedimentary Geology at Chengdu University of Technology, concluded that between 700 million and 200 million years ago, the distance between Earth and the moon increased by around 20,000km (12,000 miles), causing the length of the day to increase by about 2.2 hours.