Scientists have noticed that the Earth is speeding up; it is moving so much faster now that they want to modify the length of a day. A day on Earth is known as 24 hours or 1,440 minutes or 86,400 seconds; this is the time required for Earth to spin once around on its axis, creating day for areas facing the sun, and night for those away from it. But don’t throw out your watches and calendars quite yet; the difference in speed is only in seconds, although even seconds can have big impact to things on and beyond Earth.
In general, the speed of the Earth’s rotation has slowed down over time. The de-acceleration has also changed over time; the Earth’s molten core, fluid atmosphere, and liquid oceans, combined with gravitational influences by nearby bodies such as the Moon, can help slow down the slowing down of the Earth’s spin. Precision atomic clocks, space systems, and high-tech computer systems require sophisticated, highly accurate time measurements. The International Earth Rotation and Reference Systems Service (IERS) monitors this slow down and adds “leap seconds” to the official Coordinated Universal Time (UTC) that is the gold standard in time measurement and time keeping on the planet. The UTC time standard, widely used for international timekeeping and as the reference for civil time in most countries, uses precise atomic time. The addition of “leap seconds” adjusts these atomic clocks to keep the right time in sync with the speed of the Earth.
Since the 1970’s, a total of 27 leap seconds have been added to the official time to address the slowing speed of Earth’s rotation. The last leap second was added on New Year’s Eve in 2016. However, that suddenly changed during 2020.
On July 19, 2020, the actual day on Earth was 1.4602 milliseconds shorter than a full 24 hours, making it the shortest day ever recorded. Since then, the record short day has been broken a total of 28 times. Now in 2021, days are spinning faster, nearly 0.5 milliseconds shorter than a full 24 hours.
Peter Whibberley, a senior research scientist with the National Physical Laboratory’s Time and Frequency Group, told “The Telegraph”, “It is certainly correct that the Earth is spinning faster now than at any time in the last 50 years…It’s quite possible that a negative leap second will be needed if the Earth’s rotation rate increases further, but it’s too early to say if this is likely to happen.”
A negative leap second would have the opposite effect of a leap second; rather than adding a second when needed, one would simply be removed. A negative leap second has never been used before.
Whibberley added, “There are also international discussions taking place about the future of leap seconds, and it’s also possible that the need for a negative leap second might push the decision towards ending leap seconds for good.”
The difference in time is insignificant on the surface to humans, but very significant to human activity. Scientists say it would take another 100 years of this acceleration to be noticable where you’d be able to “see” the Earth speeding up and time moving faster. But for the technology that humans depend on, these changes could be extremely problematic. As an example, communication and navigation systems based on modern satellite technology depend on time being consistent with the usual positions of the Sun, Moon, and stars. But if these systems are off by even milliseconds, they can fail , rendering the tools humans use broken.
While scientists scramble to figure out why these time shift is happening and how to prevent systems from failing because of it, one thing is sure: 2021 is likely to become the shortest year ever on record due to how fast the Earth is spinning.
