Latest news with #LeapSecond
Gizmodo
7 days ago
- Science
- Gizmodo
Earth's Unusual Rapid Spin Could Prompt First-Ever ‘Negative Leap Second'
The Earth has been spinning unusually fast recently. Last year on July 4, our planet set a record by completing a full spin 1.66 milliseconds (0.00166 seconds) faster than usual, according to One year later, on July 10, 2025, Earth completed a daily rotation that scientists estimate was 1.36 milliseconds faster than usual, giving us another particularly short day. Other shorter (but ever-so-slightly longer) days occurred on July 9 and July 22, although the exact margins have yet to be confirmed. Losing a couple milliseconds may seem insignificant to most of us—perhaps justifiably so. But tiny error margins in time can mess up systems that depend on extremely precise calculations, such as high-speed communication networks, GPS, or banking systems. As such, scientific timekeepers use highly sophisticated atomic clocks to set the standard via the Coordinated Universal Time (UTC). But with the recent acceleration in Earth's rotation, the need for a 'negative' leap second has re-emerged among some timekeeping experts. Scientists regularly apply a leap second to keep UTC synchronized with astronomical time, which they base on Earth's rotation. A full day on Earth—the time it takes our planet to complete one full rotation on its axis—lasts for 86,400 seconds. But factors such as the Sun's position, the Moon's orbit, and Earth's gravitational field influence how quickly the Earth completes its daily cycle. As a result, Earth's rotation ends up being irregular, and slight differences between UTC and astronomical time can add up in the long run, causing a mismatch between the two. Leap seconds correct for this deviation. By the same logic, a negative leap second would subtract an extra second from UTC to account for the milliseconds we're losing from Earth's faster rotation. Now, this may seem perfectly reasonable, but not all scientists agree. In fact, some scientists found the leap second so problematic that, in 2020, an international group of experts voted to phase out the practice by 2035. As computing networks became more globally interconnected, the leap second began to cause 'failures and anomalies in computing systems,' Patrizia Tavella, director of the International Bureau of Weights and Measures' time department, told Live Science in a 2022 interview. Moreover, countries account for leap seconds in different ways, causing major complications for airlines scheduling international flights, she said. Critics of the proposed negative leap second cite similar concerns. To be clear, no formal institution or body is currently advocating for the negative leap second. But should that happen, squeezing in the negative leap second to our timekeeping system will be difficult given the increasingly interconnected nature of our society, Darryl Veitch, a computer networking expert, explained to Live Science in a recent interview. 'There are continuing problems with the insertion of positive leap seconds even after 50 years,' Judah Levine, a physicist at the University of Colorado, told Live Science. 'And this increases the concerns about the errors and problems of a negative leap second.' It seems unlikely, therefore, that scientists will actually adopt the negative leap second, especially since they've already decided to retire the positive leap second. But given Earth's recent shorter daily spins, astronomical time might eventually fall behind UTC, forcing the need for negative leap seconds. Levine puts the likelihood of this happening at 30% in the next decade or so, although last year, Duncan Carr Agnew, an oceanographer at the Scripps Institution of Oceanography, argued in a paper from last year that this could occur as early as 2029. However, Veitch also believes our planet might slow down soon, which would be consistent with longer-term trends on record. But we'll just have to see—and you can, too! Timekeepers estimate that our next 'short' day will fall on August 5.
The Independent
23-07-2025
- Science
- The Independent
Earth is spinning faster and is about to see one of its shortest days ever
The Earth is spinning at its fastest rate since records began, and astronomers predict that 5 August will be one of the shortest days ever measured. New estimates released this month suggest that the first Tuesday of August will be around 1.25 milliseconds shorter than it should be. The average rotation of our planet is 24 hours, or 86,400 seconds, however there are several variables that cause Earth to spin faster or slower. The Moon's gravitational influence on Earth typically causes it to slow time over time and for days to lengthen. There is no conclusive reason for why Earth's rotation is accelerating, though a 2024 study suggested that melting polar ice caps and rising sea levels could be influencing it. The shortest day ever recorded was on 5 July, 2024, measuring 1.66 milliseconds shorter, with recent years seeing the rotation speeding up. Scientists have proposed a negative leap second to compensate for the lost time, meaning all of the world's clocks will need to be adjusted. 'This is an unprecedented situation and a big deal,' said geophysicist Duncan Agnew from the University of California, who wrote about the issue in a paper published in the journal Nature last year. 'It's not a huge change in the Earth's rotation that's going to lead to some catastrophe or anything, but it is something notable. It's yet another indication that we're in a very unusual time.' There have been 27 leap seconds added to Coordinated Universal Time (UTC) since 1972, when the present form of the time standard was adopted, in order to match atomic time to astronomical time. This would be the first time that a second has been subtracted, and it is not clear how current computing infrastructure would cope with the shift. Patrizia Tavella from the Time Department at the International Bureau of Weights and Measures, wrote in an accompanying article to the Nature paper that any potential risks should be assessed before a negative leap second is applied. 'A negative leap second has never been added or tested,' she said, 'so the problems it could create are without precedent.'
Yahoo
10-07-2025
- Science
- Yahoo
Earth's Rotation Is Speeding up this Summer. Here's Why
The moon shapes Earthly days Credit - Getty Images If you're the kind of person who gets a lot done, you're grateful for every one of the 86,400 seconds that make up a day. On July 9, however, as well as on July 22, and August 5, you won't get your full complement of seconds. On these days the Earth will be measurably—and, so far, unaccountably— accelerating its rotation, shaving from 1.3 to 1.5 milliseconds off of the usual 24 hours the typical day gets. A millisecond, or one thousandth of a second, is admittedly not much—an eyeblink takes about 100 milliseconds. But with atomic clocks tracking the Earth's rotational speed so closely that once every year and a half or so, the International Earth Rotation and Reference Systems Service (yes, there is such a thing) has to add a leap second to the year to account for any increase in the planet's speed, every millisecond counts. So what's behind the sudden speed-up and what effect could it have? Around the world, there are 450 atomic clocks in operation, tracking the time with an accuracy that sees them gaining or losing only about 1 second every 100 million years. The clocks exist for more than just tidy temporal bookkeeping. Everything from weather satellites to GPS satellites to telecommunications to nuclear missiles and other weapons of war rely on precise timing to operate properly. So when both astronomers and the operators of the clocks notice that the atomic ticks are falling out of step with the rotation of the Earth, people take notice. The shortest day ever recorded since atomic clocks went into operation in the 1950s occurred last year, on July 5, according to Date and Time, when the Earth shaved off 1.66 milliseconds. Three years earlier, on June 30, 2022, things moved similarly quickly, when the day came in 1.59 milliseconds under the 24-hour wire. But with three short days predicted over the next few weeks by astronomers and clock watchers, this summer is something even more rare. There are a number of reasons the Earth may be changing its speed this way. But it's not clear yet just which explanation is responsible this time. The likeliest cause is the position of the moon. Lunar distance is an always-changing thing, with the moon tracing an elliptical orbit around the Earth. At its closest approach—or perigee—the moon is only 224,000 miles distant. At its furthest—or apogee—that gap widens to 251,655 miles. On the three speedy days this summer, the moon will be at or near apogee—which is a puzzle, since lunar gravity is such that the Earth tends to slow down, not speed up, when the moon is farther away. The moon's orbit is not only elliptical, however, but cockeyed too, angled anywhere from 18° to 28° relative to the Earth's equator. The sharper that angle is the faster the Earth orbits, with lunar gravity in this case speeding things up, countering the braking effect that lunar apogee usually applies. On the three days in question this summer, the moon will be close to its 28° peak. The moon is not the only thing that can shorten earthly days. Earthquakes can too, redistributing subterranean mass and causing the planet to accelerate or slow down in the same way a figure skater can change the speed of her spin when she tucks in or extends her arms. In 2005, an earthquake in Indonesia shifted the Earth's polar mass about one inch toward the east, decreasing the length of a day by 2.68 microseconds—or millionths of a second. No significant earthquake has occurred recently, however, ruling temblors out as the cause of the current speed up. Climate change—again and seemingly always—may play a role too. Last year, two NASA-funded studies found that since 2000, melting glaciers have caused the axis of the planet—or the centerpoint of its spin—to shift by about 30 ft., changing the speed of rotation. The catch is, in this case the change causes the planet to decelerate, not speed up—by about 1.33 milliseconds per century. If warming continues at its present pace, it is projected to increase the length of our days by 2.62 milliseconds by the end of the century. Other factors, including rising ocean levels and the warming—and thus swelling—of the atmosphere can make a difference too, slightly increasing planetary circumference. Even the springtime blossoming of trees can play a role. 'In northern summer, the trees get leaves,' geophysicist Richard Holme of the University of Liverpool told Live Science. 'This means that mass is moved from the ground to above the ground—further away from the Earth's spin axis.' In all of these cases too, however, the effect is to slow the Earth, not speed it up. So that brings scientists back to lunar gravity as the cause of the current acceleration—and that's a reason not to fret the slightly shorter days. The Earth and the moon have been doing their dance for the better part of 4.5 billion years, and it's always been a stable one. Here's betting they've got a few billion more years yet in their run. Write to Jeffrey Kluger at
