This summer Earth recorded the shortest day in its history, tied to the fastest rotation ever observed. Scientists explain that a wobble in the planet’s orientation likely allowed a spin to finish in just a fraction of a second shorter than the usual 24 hours.
On June 29, 2022, Earth completed one full rotation in 23 hours 59 minutes 59.99 seconds, a gap of about 1.59 milliseconds under the standard day length, according to timeanddate.com. And in late July, another day came in roughly 1.50 milliseconds shorter than the solar day, signaling that the trend persisted.
To gauge the true length of a day, scientists track Earth’s rotation by measuring the moment a fixed star crosses a specific point in the sky each day.
this is not the first
In recent years, Earth has shown a pattern of faster spins. In 2020, a very short month record emerged, with the planet rotating more quickly than in decades. The year also set a new mark for the shortest astronomical day, surpassing a longstanding 2005 record.
The shortest day of 2020 occurred when Earth completed a rotation about 1.0516 milliseconds quicker than 86,400 seconds, a measurement tied to the elapsed time relative to the Sun. Later that same year, July 19 produced an even shorter day by about 1.4602 milliseconds. The year also included several notably brief days since the 1960s, and while the following year showed ongoing high speeds, no new record was set—until now.
Despite these spikes, the long-term trend is a gradual slowdown in Earth’s overall rotation. On average, each century introduces small shifts of a few milliseconds per day. Yet the day-to-day pace can swing by a fraction of a millisecond, producing occasional breaks in the pattern where days shorten instead of lengthening.
Why is the world speeding up or slowing down?
The reasons behind varying rotational speeds and changing day lengths are not fully settled, but several explanations are commonly discussed. The most widely accepted involve a mix of tidal interactions, internal dynamics, and surface mass distribution.
The day-night cycle does not align perfectly with Earth’s axis, which tilts and wobbles over time. The planet also has an equatorial bulge, making its shape slightly oblate. Tidal forces from oceans and the Moon’s gravity can subtly alter spin, while melting glaciers may redistribute mass away from the poles. Some researchers emphasize a conjunction of factors rather than a single cause, and ongoing studies continue to refine the picture.
On June 29, 2022, the planet completed a full rotation in a speed faster than the standard day by about 1.59 milliseconds.
Chandler’s Tremor
Scientists are exploring why days sometimes shorten, and a possible link points to the Chandler wobble, a small movement in Earth’s rotation axis. Researchers Leonid Zotov, Christian Bizouard, and Nikolay Sidorenkov presented a theory at a regional geoscience conference suggesting this wobble behaves like a spinning top gaining momentum or slowing down.
The wobble was first noted by the astronomer Seth Chandler in the late 19th century. For a time, the wobble’s amplitude is described as a few meters on Earth’s surface, though it showed a lull from 2017 to 2020.
If rapid rotation continues, it could prompt consideration of a negative leap second to keep civil time aligned with solar time. A negative leap second would mean skipping a second, a change that could disrupt computer systems and data logging.
The true day length is measured by IERS scientists through precise timings of a fixed star passing a given sky position each day. This measurement is known as Universal Time UT1, and it is compared against the International Atomic Time TAI, a composite of about 200 atomic clocks around the world. The deviation between UT1 and TAI over 24 hours defines the actual day length. At present, no new leap seconds are scheduled.
The World Orientation Center notes that leap seconds have advantages and drawbacks. They help keep astronomical time in sync with the clock but can complicate some data logging and communications systems. Some scientists have proposed widening the gap between astronomical and atomic time for a period, potentially leading to a future system that minimizes disruption while preserving accuracy.
Reference Articles:
Time and Date: Shortest Day 2022
Infobae: Earth spinning faster than normal and setting a new day record
…….
Environment department contact address:[redacted]