The 28 fastest days on record (since 1960) all occurred in 2020, with our planet completing its revolutions milliseconds quicker than average.

Don’t worry -- this doesn’t mean that we’re all going to fly off the planet like when you spin your kids around on a merry-go-round. But it could mess with the Keepers of Time.

The shortest day of all came on July 19, when the Earth completed its rotation in 1.4602 milliseconds quicker than the normal 86,400 seconds in a day.  The last time that an average day was less than 86,400 seconds across a full year was in 1937.

Astronomical time is set by how long it takes the Earth to make one full rotation, and when that differs from UTC (Coordinated Universal Time) by more than 0.4 seconds, it gets an adjustment.

When Earth’s rotation was slower around 50 years ago, a “Leap Second” was added. The first leap second happened on June 30, 1972. Around every 19 months, a ‘leap second’ has been added to keep time, uh, ‘on time.’ There have been 27 leap seconds in total.

Leap seconds have been added either on June 30 or on New Year’s Eve. They’ve been added at the end of the day, just before midnight.

The most recent addition of a Leap Second was New Year’s Eve 2016.

But now, since Earth is spinning faster, there could eventually be the need for a NEGATIVE leap second. Instead of adding time, they might need to subtract time.

There will NOT be a leap second added (or subtracted) this June.

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