Scientists chart Earth's ancient rotation slowdown

A joint study of geological data by Chinese and foreign researchers has revealed that the Earth's rotation decelerated in a step-like pattern 700 million to 200 million years ago.

Throughout the Earth's history, its rotation has been gradually slowing down due to factors such as tidal dissipation, glacier melting and tectonic plate movements. However, the variation of the rate of deceleration through time has not been established.

In a paper published last week in the journal Proceedings of the National Academy of Sciences, researchers said there were two intervals — from 650 million to 500 million years ago and 350 million to 280 million years ago — when the deceleration of rotation was high, separated by an interval of stalled deceleration from 500 to 350 million years ago.