A Day in the Life Used to Be 17 Hours

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https://eos.org/articles/a-day-in-the-life-used-to-be-17-hours

By Emily Shepherd, Eos/AGU. 

Excerpt: The Moon was a lot closer to Earth 2.46 billion years ago, and the shorter distance contributed to shorter days. ...new research has calculated the distance of the Moon 2.46 billion years ago, nearly doubling the age of the previous estimate. Because the length of the day is tightly, tidally tied to the location of the Moon, the research has also calculated how long a day lasted at the time: 17 hours. ...To determine the distance of the Moon, scientists studied rhythmic patterns in Earth’s orbit and axis called Milankovitch cycles, explained Margriet Lantink, a geologist at the University of Wisconsin–Madison and lead author of the new studyin the Proceedings of the National Academy of Sciences of the United States of America....

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