On July 29, the Earth broke its record for the shortest day. Our planet completed a full spin in 1.59 milliseconds less than its regular 24-hour rotation. Earlier, on July 26, Earth broke its June record by completing a full spin in a time that was 1.50 milliseconds slower than it regular time.
According to the UK-based publication Independent, the planet recently has been increasing its speed. Back in 2020, the Earth saw its shortest month that has ever been recorded since the 1960s. On July 19 of that year, the shortest of all time was measured. It was 1.47 milliseconds shorter than a typical 24-hour day.
Once upon a time Earth took exactly 24 hours to rotate once on its axis, but not anymore.
Indian media publication Mint reported that until a few years ago scientists thought that Earth’s rotation was slowing down. The International Earth Rotation and Reference Systems Service (IERS) had even begun adding leap seconds to make up for the slower spin. This was done until December 31, 2016.
So, is the world speeding up? Over the longer term – the geological timescales that compress the rise and fall of the dinosaurs into the blink of an eye – the Earth is actually spinning more slowly than it used to. Wind the clock back 1.4bn years and a day would pass in less than 19 hours. On average, then, Earth days are getting longer rather than shorter, by about one 74,000th of a second each year. The moon is mostly to blame for the effect: the gravitational tug slightly distorts the planet, producing tidal friction that steadily slows the Earth’s rotation, reported UK-based media publication Guardian.
According to Nasa, stronger winds in El Niño years can also slow down the planet’s spin, extending the day by a fraction of a millisecond. Earthquakes, on the other hand, can have the opposite effect. The 2004 earthquake that unleashed a tsunami in the Indian Ocean shifted enough rock to shorten the length of the day by nearly three microseconds.
Indian media publication Mint further reports that, the faster rotation of Earth has consequences because it could lead to the introduction of the negative leap second in order to keep the rate that the Earth orbits the Sun consistent with measurements from atomic clocks. The negative leap second will also affect IT systems. This is because a clock usually runs from 23:59:59 to 23:59:60 before resetting to 00:00:00.
