Geoscientist Stephen Meyers with the University of Wisconsin, Madison, and a colleague determined that almost 1.5 billion years ago a day lasted just over 18 hours, according to National Geographic. That means on average, a day has grown by about one 74 thousandths of a second every year since Precambrian times, and it's still lengthening.
The results of Meyers' study were published in the Proceedings of the National Academy of Sciences.
The reason days are ever so slowly growing longer is because of the gravitational relationship between the Earth and the moon, National Geographic reported.
“So, if I just wait a few hundred million years, I’ll get that extra hour back,” Meyers joked.
The moon moves further away as the Earth's rotation gradually decreases, The Guardian reported, and over the past 1.4 billion years the moon has drifted more than 27,000 miles from the Earth, according to the study. It's now almost 239,000 miles away. The closer the moon was to the Earth, the stronger it's gravitational pull.
Meyers calculated the numbers by using astronomical theory and geochemical signatures in ancient rocks to show that a day on Earth was once 18 hours and 41 minutes.
Scientists, like geophysicist Kurt Lambeck from the Australian National University, told National Geographic that the Earth's spin has been slowing for billions of years because of the drag the moon has on the tides. The drag slows the Earth's rotation by about 1.78 milliseconds every century, enough to add up over billions of years and lengthening Earth's days.
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