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PortuguêsEarth's rotation accelerated on Tuesday, shortening the day by 1.25 milliseconds due to lunar positioning, atmospheric changes, and core shifts. This marks the third such event this summer, potentially requiring history's first negative leap second for timekeeping systems.
Earth's Unusual Speed Boost
On Tuesday, Earth completed its rotation 1.25 milliseconds faster than usual, making it the shortest day recorded since precise measurements began. This phenomenon marks the third such acceleration event this summer, following similar occurrences on July 10 (-1.36 ms) and July 22 (-1.34 ms).
Scientific Explanation
Professor Katrien Kolenberg explains: "Like a skater pulling in their arms, Earth spins faster when mass redistributes closer to its axis. Currently, three factors converge: the Moon's position farther from Earth's equator brings tides closer, summer atmospheric patterns alter wind circulation, and shifts in Earth's molten core cause the outer layers to accelerate."
Historical Context
This acceleration reverses Earth's long-term slowing trend. Over 4.5 billion years, Earth's rotation has gradually slowed from 10-hour days to our current 24-hour cycle, mainly due to the Moon's gravitational pull. Since 1972, 27 leap seconds have been added to compensate for this slowing.
Future Implications
If acceleration continues, scientists may implement the first negative leap second - removing one second from global timekeeping. While imperceptible to humans, this poses challenges for GPS satellites, financial systems, and computer networks where millisecond precision matters. The International Earth Rotation Service monitors these changes to determine if timekeeping adjustments become necessary.
