2021 is the shortest year in history

The faster Earth's rotation makes 2021 about 65 milliseconds shorter on average.

Many people may not realize it, but 2021 is shorter than usual. TimeAndDate science communicator Graham Jones told Newsweek on December 31 that last year was about 65 milliseconds shorter than average and was the shortest year on record.

The Earth's rotation rate affects the length of a year.

The cause is the speed at which the Earth rotates. Even a small change in the rotation of the blue planet can make a day a fraction of a second longer or shorter than the average of 86,400 seconds.

"If you look at the length of a day throughout the year, you can see peaks and troughs. Some of the important factors that affect that are the Moon's orbit and the Moon's distance from the Earth." Graham said. This is a relatively short-term effect, but other factors, such as ocean motion and movement within the blue planet are thought to have a longer-term effect, but scientists don't fully understand how. awake. Therefore, it is difficult to make predictions about the Earth's rotation rate earlier than 6 months.

In general, scientists think that the Earth has slowed down for a long time, causing the years to gradually lengthen, according to Graham. They infer this from factors such as geological features or observations of eclipses.

"What's interesting in 2020 is that we're seeing the Earth explode in speed. Acceleration has slowed but the Earth continues to spin so 2021 is going to be faster. This year is likely to be shorter as well. a little bit, but it's hard to say for sure," Graham explained.

Official figures for the length of a day are published by the International Earth Rotation Office (IERS). It is also the organization that makes leap seconds decisions if the Earth's rotation speed exceeds or lags too much behind schedule.

Since the 1960s, scientists have been measuring the length of days with atomic clocks - extremely accurate clocks that are not faster or slower than 0.00000001 seconds per year than the ideal clock. Thanks to atomic clocks, scientists know exactly when day lengths deviate from the average.

"When atomic time was internationally accepted in 1967, atomic clocks were more than 100 times more stable than the solar year. Over the past 30 years, atomic clocks have been improved by more than a million times." Atomic clock expert Kurt Gibble, professor of physics at Pennsylvania State University, said.

"Today's atomic clocks can accurately test our knowledge of fundamental physics, ensure secure financial transactions, provide the required time - accurate to a billionth of a second - for mapping systems that use the Global Positioning System (GPS) to guide vehicles to nearly any address on Earth," added Gibble.