Earth’s Rotation Slowed During Key Life Events
Recent research indicates that Earth's rotation slowed significantly during two crucial periods: the Cambrian explosion of life and the Great Dying, a mass extinction event. A team of Chinese scientists led by Ma Chao from the Institute of Sedimentary Geology at Chengdu University of Technology conducted a two-year study, revealing that this phenomenon impacted the planet millions of years ago.
Mechanisms Behind the Deceleration
Although Earth seems to rotate consistently, its spin does not remain fixed at 24 hours. Variations in gravitational forces caused by the distance between Earth and the Moon impact rotation speed. Changes in ocean tides from these gravitational shifts contribute to a slight deceleration of the Earth's spin. Additionally, as Earth transfers momentum to the Moon, it gradually moves outward.
The study observed an increase of 20,000 km in the distance between the Earth and the Moon between 700 million and 200 million years ago. This change extended Earth's day by approximately 2.2 hours. The researchers identified two significant intervals of this slowed rotation: from 650 to 500 million years ago and from 350 to 280 million years ago.
Historical Context of Events
The first slowdown coincided with the Cambrian explosion when complex life forms diversified rapidly. The second deceleration occurred around 250 million years ago, aligning with the Great Dying or Permian-Triassic extinction event, which extinguished 90% of Earth's life.
Volcanic activity, in conjunction with climate changes, fluctuating sea levels, and salt concentrations, contributed to this extinction. Ma also noted that changing sea conditions were linked to Earth's rotational changes. He stated, "The two major ‘fast-slow’ deceleration periods may have provided the necessary conditions for the early evolution of marine ecosystems," highlighting the interconnectedness of Earth's rotation and life on the planet.
Earlier, SSP reported that a worlds fastest microscope captures electron motion.