'Scientists used a combination of astronomical theory and geochemical signatures buried in ancient rocks to show that 1.4bn years ago the Earth turned a full revolution on its axis every 18 hours and 41 minutes.

The number means that, on average, the length of the day on Earth has grown by approximately one 74 thousandth of a second per year since Precambrian times, a trend that is expected to continue for millions, if not billions, of years more.

As the Earth’s rotation gradually winds down, the moon moves further away. Writing in Proceedings of the National Academy of Sciences, Stephen Meyers at the University of Wisconsin-Madison and Alberto Malinverno at Columbia University in New York calculate that over the past 1.4bn years the moon has drifted about 44,000km from Earth to a distance of 384,400km.'

[theguardian.com]