2023-06-19 06:00:17
According to a new study, the length of a day on Earth once stabilized at 19 hours for no less than a billion years, before increasing again to reach our current 24 hours. The study was conducted by Ross Mitchell, geophysicist at the Institute of Geology (Geology, from Ancient Greek γη- (gê-, “earth”) and…) and Geophysics of the Academy (An academy is an assembly of men of letters, scholars and/or artists recognized by their…) Chinese Sciences, and Uwe Kirscher, researcher (A researcher (fem. researcher) designates a person whose job is to do research…) at the University (A university is an establishment of higher education whose objective is the…) Curtin Australia (Australia (officially the Commonwealth of Australia) is a country of…)
Image d’illustration Pixabay
Several billion years ago, Earth’s days were much shorter. This is explained by the proximity of the young Moon which, over time, has “stolen” rotational energy from the Earth to raise its orbit (In celestial mechanics, an orbit is the trajectory that draws in the space a body…).
To measure the length of a past day, the researchers used cyclostratigraphy, a geological method that relies on the rhythm of sedimentation to detect Milankovitch cycles, cyclical variations in parameters of the Earth’s orbit. These cycles reflect the variations caused in particular by changes in the speed (We distinguish:) of rotation of the Earth.
In the past, two Milankovitch cycles, precession and obliquity, were related to oscillation (An oscillation is a periodic motion or fluctuation. Oscillations are either at…) and tilt (In mechanics celestial, the inclination is an orbital element of a body in orbit…) of the axis of rotation of the Earth. The researchers were therefore able to detect the faster rotation of the early Earth by observing shorter cycles of precession and obliquity.
The study suggests that the length of the day, in its progression, would have stagnated at a constant value. Indeed, in addition to the ocean tides linked to the attraction of the moon, the Earth is also subject to solar tides, caused by the heating of the atmosphere during the day. These opposing forces could have created a resonance (Resonance is a phenomenon whereby certain physical systems…) of the tides, resulting in a constant day length lasting one billion (One billion (1,000,000,000) is the whole natural which follows nine hundred …) years.
Day length in the Precambrian and trends.
Credit: Nature Geoscience
Day length correlates with oxygen levels on Earth. The study therefore supports the idea that during periods of increased day length, photosynthetic bacteria were able to generate more oxygen.
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