What is a ‘Negative leap second’?

August 2, 2022

On July 29, 2022, Planet Earth made rotation on its axis in less than 24 hours. Reports are suggesting that, it is spinning faster. On July 29, it broke its own record for shortest day, by completing the rotation in less than 1.59 milliseconds. As a result of this, day on earth was shorter by 1.59 milliseconds, than usual 24-hour day.

Highlights:

Earlier, the shortest day on Earth was recorded on July 19, 2020 since the 1960s. In 2020, Earth’s rotation was shorter by 1.47 milliseconds, than the usual 24-hour day.
Earth continued to rotate faster in 2021 as well. However, it did not create any new records.
But according to Interesting Engineering (IE), which is a community for lovers of engineering, technology & science, noted that a 50-year era of shorter days is likely to become a norm. It has already flagged off.

Causes of faster rotation:

Answer to why the planet is rotating at a faster speed is not yet known.
However, as per some scientists less weight on the poles due to melting of glaciers, is the cause of faster spin.
On the other hand, others suggest that, molten core of earth’s interior is moving over time.
Seismic activity could also be responsible for faster rotation.
Chandler Wobble is another reason, suggested by some scientists. Chandler Wobble means little change or departure in Earth’s axis of rotation.

Negative Leap Seconds:

As the rotation speed of the Earth is rotating, it could result into “Negative Leap Seconds”. This phenomenon happens to maintain the rate on which earth orbits across the Sun in consistent with measurement from atomic clocks. It would have confusing outcomes for computers, smartphones and other communications systems. It would also impact IT systems, because a clock usually runs from 23:59:59 to 23:59:60 and restarting at 00:00:00. But time skip could crash programmes and corrupt data. To solve this problem, international timekeepers would require to add negative leap second, which is called as a “drop second”.

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