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Dec 28, 2021 · While the Earth’s spin has slowed down since last year, it’s still spinning slightly faster than average. Research shows the average length of a day in the first half of 2021 was 0.39 ...
- Earth Accelerated in 2020
- Earth Settles Down in 2021
- Still Spinning Fast
- “The Specter of A Negative Leap Second”
- We Don’T Know What Happens Next
- The Unpredictability of Earth’s Rotation
- “Most People Won’T Notice A Missing Second”
In the midst of the general turmoil of 2020, Earth put on a burst of speed. Generally speaking, with respect to the Sun, our planet rotates once every 86,400 seconds. This equals 24 hours, or one mean solar day. In practice, the time Earth takes to complete one spin varies by milliseconds (where 1 millisecond equals 0.001 seconds). Since the 1960s,...
Then, in the third quarter of the year, things settled down. Between July 1 and September 30, the average length of a day in 2021 was a fraction longer—0.05 milliseconds more—than in 2020. The shortest-day record from 2020 was not bettered in 2021, although Earth came within a few thousandths of a millisecond on July 9. The following chart compares...
As things currently stand, therefore, Earth is no longer gaining speed. But the excitement hasn’t ended. Our planet continues to spin, on average, ahead of its 86,400-seconds-per-day schedule. This means the time of day based on Earth’s rotation, referred to as UT1, is running faster than the time determined by atomic clocks, known as UTC. The time...
Taking a second away from our clocks would involve skipping a second, most likely the final second of a year. Clocks would go from 23:59:58 on December 31 straight to 00:00:00on January 1. Since this has never been done before, there are concerns about the effect it may have on IT systems. A negative leap second would be problematic, thinks Dennis ...
Will a negative leap second be needed in the next decade? The fact is, we have no idea. The variations in Earth’s rotational speed are the result of the complex motion of its liquid core, oceans, and atmosphere, plus other effects. Some of these cycles are well understood. For instance, the fortnightly peaks and troughs in the 2020-21 length of day...
The following chart shows how the length of day has varied since 1830. (Although the world’s first atomic clock was not developed until 1948, historical records of lunar occultations provide information about Earth’s spin in the past. A lunar occultation is where the Moon passes in front of a star.) The orange trend line shows that, overall, Earth’...
Whether a negative second ever happens or not, it would be easier to handle than a positive one, according to Adalbert Michelic, Senior System Administrator at timeanddate.com. “For a computer program, adding a second is much more of a problem than jumping over one,” he says. “People who are running critical infrastructure will need to prepare, but...
Negative Leap Seconds. Leap seconds can be positive (1 second added to the schedule) or negative (1 second omitted). So far, all leap seconds have been positive. However, if the Earth's rotation keeps accelerating, as it has done in 2020, the IERS may decide to announce the world's first negative leap second at some point in the future. Days ...
A negative leap second would suppress second 23:59:59 of the last day of a chosen month so that second 23:59:58 of that date would be followed immediately by second 00:00:00 of the following date. Since the introduction of leap seconds, the mean solar day has outpaced atomic time only for very brief periods and has not triggered a negative leap second.
Dec 31, 2021 · The International Earth Rotation and Reference Systems Service announced in July 2021 that there’d be no leap second added to the world’s official timekeeping in December 2021. The last leap ...
A negative leap second is a second that is subtracted from our clocks to keep them in sync with the Earth's rotation. It is the opposite of a positive leap second, which is a one-second addition to our clocks. The system of leap seconds was introduced in the early 1970s. So far, there have been 27 positive leap seconds, but no negative leap ...
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Oct 22, 2021 · But we still may need a negative leap second. News. ... The first half of 2021 was still speedy, with the average length of a day clocking in at 0.39 milliseconds less than in 2020. But from July ...
