Earth sets record for the shortest day

[Admin]

June 29, 2022 broke records for Earth's shortest day, but does this mean our planet is spinning faster?

Earth sets record for the shortest day : Read more

 

[rod]

Earth's rotation and slow down or speed up is the subject of much astronomical study too. Here is an example.

Historical eclipses, https://ui.adsabs.harvard.edu/abs/1982SciAm.247d.170S/abstract

"Calculations based on this and several other observations reveal an average rate of day lengthening since ancient times to be 1.78 + or - .11 milliseconds per century."

Reference paper, Historical Eclipses, https://www.scientificamerican.com/article/historical-eclipses/, October 1982.

"Reliable records of solar and lunar eclipses go back as far as 750 B.C. They bear on such questions as whether the sun is shrinking or the earth is not spinning as fast as it once did."

My observation. "Calculations based on this and several other observations reveal an average rate of day lengthening since ancient times to be 1.78 + or - .11 milliseconds per century." My note. The Earth's LOD is slowing down and solar and lunar eclipse measurements supports this. The rate used in this report is 1.78E-3 s/100 years. That works out to be 1.78E-5 s/yr rate of slow down. In 4 billion years, the Earth's LOD slows down 7.12E+4 seconds or 19.78 hours, thus Earth's LOD 4.22 hours using linear rate of change and extrapolation, 4 billion years ago. Using the present Earth mass and radius, spin rate at equator ~ 2.64 km/s.

The slowing down of Earth's Day is important in the giant impact model for the origin of the Moon too. The Moon must form much closer to Earth with a lunar month near a day and only about 3-6 earth radii distance compared to the mean near 60.3 earth radii today.