Today marks the shortest day of the year, as Earth’s rotation speeds up, causing the planet to complete its rotation 1.3 milliseconds faster than the standard 24 hours.
According to BBC Science Focus, while summer normally features longer daylight hours, the day of July 9th will be slightly shorter due to Earth’s increased rotational speed. Typically, our planet takes exactly 24 hours—or 86,400 seconds—to complete one rotation around its own axis; however, this rotation speed occasionally fluctuates by small margins.
The International Earth Rotation and Reference Systems Service (IERS), established specifically to monitor and measure variations in Earth’s rotation, continuously tracks these small rotational fluctuations and their effects on day length.
The IERS first reported an increase in Earth’s rotation rate in 2020, and since then, data has shown a gradual but noticeable accelerating trend. As a result, certain calendar days have been predicted to experience slightly shorter durations than the standard 24-hour cycle.
Along with July 9th, the IERS has also predicted July 22nd and August 5th—dates when the Moon will be positioned farthest from Earth’s equator—to be among the shortest days of the year.
