FORT WAYNE, Ind. (WFFT) — 2020 was a difficult year, and many wanted it to end faster than it did.
According to timeanddate.com, Earth felt the same way because it has been spinning unusually fast.
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28 of the shortest days since 1960 happened in 2020.
On average, the planet spins once on its axis every 86,400 seconds.
That equals 24 hours, or one solar day.
If you remember the Broadway musical Rent, it takes 525,600 minutes to rotate the sun.
Highly accurate atomic clocks were developed in the 1960s.
They showed that a mean solar day can vary by milliseconds.
Certain factors can either speed up or slow down the Earth's spin each day.
These factors include atmospheric pressure, ocean currents, wind, and movement of the planet's molten core.
This impacts the milliseconds of Earth's spin, but they can add up.
A millisecond equals 0.001 second.
It results in the highly accurate atomic clock being knocked out of sync with astronomical time.
Atomic clocks are important because they are used to set Coordinated Universal Time, UTC.
That's how everyone on the planet can agree on what time it is.
Before last year, the shortest day was July 5, 2005.
That's when the Earth rotated in 1.0516 milliseconds less than the average 86,400 seconds.
The shortest day in 2020 happened on July 19.
Earth completed its rotation in 1.4602 milliseconds less than 86,400 seconds.
Scientists believe Earth's faster rotational spin will continue into 2021.
Using a mathematical equation to calculate the mean solar day, the researchers believe the average day in 2021 will be 0.05 milliseconds shorter than 86,400 seconds.
Over the course of the year, atomic clocks will be off by 19 milliseconds.
According to livescience.com, when astronomical time deviates from UTC by more than 0.4 seconds, UTC will be adjusted.
Positive or negative leap seconds can be added to the equation to sync the clocks back up as needed.
Leap seconds were introduced in 1972 and they have only been positive so far.
That means they have added an extra second to clocks, allowing Earth to catch up.
Leap seconds have been added every year and a half on average, according to the National Institute of Standards and Technology.
If the Earth continues to spin at a faster rate, then we may need to add a negative second to catch up.
This year is predicted to be the shortest in decades.
1937 was the last time an average day was shorter than 86,400 seconds over a full year.
A leap second is different from a leap year.
Leap seconds are used as needed, whereas leap years are necessary.
A solar year is actually 365.2422 days, not 365.
Therefore, February 29th is added every 4 years to compensate for the partial day.
