Our days are getting longer and it’s all thanks to the moon

Alex Lee June 6, 2018

Sitting at your desk wondering how it’s not bedtime yet? I have some bad news for you. According to scientists from Wisconsin, Madison and Colombia Universities, the days on Earth are only about to get longer as the moon spins further away from our planet.

Our days are getting longer and it’s all thanks to the moon

In the study, published in the Proceeding of the National Academy of Science, the researchers describe how they used Milankovitch climate cycles and statistical modelling to figure out how the length of days on Earth changed over the past billion years. By looking at the Earth’s Milankovitch cycles, they were able to see how the Earth has tilted and wobbled, as well as how the climate has shifted to give us our lengthened days. This data is, surprisingly, all captured in Earth’s ancient rocks, which are then able to be analysed using astrochronology.

“As the moon moves away, the Earth is like a spinning figure skater who slows down as they stretch their arms out,” Stephen Meyers, geoscience professor and co-author of the study said. “One of our ambitions was to use astrochronology to tell time in the most distant past, to develop very ancient geological time scales.”

The wobbles and tilts in Milankovitch cycles affect how much sun reaches our planet, so remodelling this data can help scientists trace the historical patterns of Earth’s climate.

With the stratigraphic data taken from two rocks – one 1.4-billion-year-old rock from Northern China and a 55-million-year-old rock from the southern Atlantic Ocean – the researchers could identify the relationship between the Earth and the moon.

According to the results, the moon has been moving 3.82cm away from Earth every single year, and that small amount is going to keep extending our days. Around 1.4 billion years ago, the days on Earth used to last just 18 hours and 41 minutes instead of the 23 hours and 46 minutes today. The moon even used to be just 22,500km away from Earth when the satellite first formed.

The moon’s not going to keep spinning away from us, however. Talking to the Guardian, the researchers explained that one day, it will hit a distance where it will stop travelling away. At that point, it will be visible from only one half of the Earth.

For now, the distance between the Earth and the moon is expected to continue to lengthen for millions of years – so those days are going to continue getting longer.