Earth’s Spin Is Slowing Down: Why Is It Happening?

Today, a 24-hour day seems too short to get everything done, but that  is actually adjusting to help out. The work of ancient astronomers shows that the Earth's spin is slowing down, though not as much as scientists believed.

As a result, the days are getting longer as the planet's rotation undergoes tiny alterations over time. However, people across the globe might not even notice this change since it will take about 6.7 million years to get one extra minute a day. This means it will take 200 million years to get one extra hour per day.

Researchers at Durham University and the U.K.'s Nautical Almanac Office collected historical data of eclipses and other celestial events between 720 B.C. and 2015. These records collected the times and places that individuals during those times witnessed various stages of solar and lunar eclipses, The Guardian reports.

Over the 2,735-year period, the scientists compared the ancient records with a computer model designed to calculate the location and time these people have witnessed past events if the planet's spin had remained constant.

"There is time and then there is how fast the Earth spins," Duncan Agnew, a geophysicist at Scripps Institution of Oceanography in San Diego, said as reported by Chicago Tribune. "Traditionally those things are closely linked, but they are not the same," he added.

The researchers have known that the Earth's rotation is slowing down because of friction brought about by tides. However, measurements of this tidal effect reveal that the planet should be slowing its rotation by 2.3 milliseconds, a little more than the new research discovers.

Many factors influence the length of an Earth day and these include climate. When the world is cold, there is more mass held at the poles, which increases the speed of rotation. On the other hand, warm climate makes the Earth bulge out more around the equator, making it spin more slowly.

The study was published in the journal Proceedings of the Royal Society.