A day has 24 hours, right? That’s 1,440 minutes. Or 86,400 seconds. That’s to say, a day is 8,64,00,000 milliseconds. Only that, at that scale, hardly any of our days hits exactly that number. As the Earth’s rotation speeds up or slows down, fractions of a millisecond are often added or subtracted, making our days a teensy bit longer or shorter on record.
June 29, 2022
On June 29, 2022, we had the shortest day ever recorded since scientists started measuring the length of each day with the precision of atomic clocks in the 1960s. June 29, 2022 was 1.59 milliseconds shorter than 24 hours.
In December 2020, the website Time and Date reported that that year alone had experienced the 28 shortest days since records were maintained. This included July 19, 2020, which was previously the shortest day on record at 1.47 milliseconds under 24 hours.
Speeding up or slowing down the rotation of any object comes down to its angular momentum, which has three components: mass of the rotating object, speed at which it moves, and the distance from the point it is rotating about. To help your understanding, imagine swivelling around in a chair. While your rotation will slow when you have your arms outstretched, you will spin faster when you pull your arms back in.
Remains a challenge
As Earth constantly redistributes its mass and angular momentum, its rotation rate and the length of the day keep changing. Scientists have a number of ideas as to why the Earth speeds up and slows down, but predicting the length of a day remains a challenge, even in the future.
This is because a number of factors are involved and there could even be a mix of several factors acting together. These include the wind, the gradual movements of mass within the Earth, the interactions where the Earth’s core meets its mantle, and the fact that the Earth isn’t exactly spherical, to name a few.
While understanding the planet’s long-term changes that influence its rotation might put us on the path towards predicting the next shortest day, scientists believe that the most recent one could likely be the result of a brief climate phenomenon such as wind speed change high in the atmosphere. As for the next shortest day, we will just have to wait and see for the moment.
Picture Credit : Google
