Earth Is About to Have Its Shortest Day Since the 1970s — And Here’s When It Could Happen
Earth might soon witness what could be the shortest day since 1973. The planet would possibly perform the fastest-ever rotation observed by a human, according to Time and Date. Astronomers have been recording Earth's rotation since 1973. Starting in 2020, experts detected the pace of rotation getting faster than ever before. Each year has offered the shortest day until that point in time. According to estimates, 2025 is also going to follow the pattern, with the shortest day supposedly happening either on July 5, July 9, July 22, or August 5, depending on the position of the Moon on that particular day.
Shortest days in July and August
Earth takes around 24 hours, which is equal to 86,400 seconds, to complete one rotation. One millisecond (ms) is equal to 1000ths of a second. The difference between the time Earth takes during the rotation, which is shorter or longer than 86,400 seconds, has been labeled the "length of day" (LOD). The LOD is determined by atomic clocks introduced in the 1950s. According to the scientists, the shortest day could happen on July 5, July 9, July 22, or August 5 in 2025. July 5 has already recorded an LOD of -1.66 ms. This implies that it took 1.66 milliseconds less than 86,400 seconds to complete rotation on that day.
According to the records, this was the shortest time, to date, taken by the Earth to rotate on its axis. This duration supposedly may have become shorter on July 9 or July 22 and could again be reduced on August 5 this year. The uncertainty is due to the Moon's positioning in its orbit. The Moon, with its gravitational pull, slows down rotation, disrupting the acceleration, per Forbes. Experts claim that the day on which the drag factor will be the weakest would be the shortest amongst the four.
Mystery of long-term variation in LODs
Until 2020, the record of the shortest LOD was deemed to be -1.05 ms by experts. However, since then, the record has been shattered every year. Experts have noted that the Earth's rotation has steadily accelerated during this period. Researchers are unsure what exactly is causing this effect, according to The Guardian. Several possibilities, like earthquakes, have been proposed, but nothing has been confirmed. Any process that impacts the planet's rotation, from disappearing glaciers to shifting continents, can facilitate its slowing down. The issue is that most of these phenomena are not perceptible by modern equipment. Hence, experts have not yet been successful in pinpointing the process that has led to the speed of rotation racking up day after day.
Time for negative leaps?
Earth's acceleration has been a surprise for experts, as, for decades, the planet has been slowing down. The Moon's drag factor, along with other reasons, has been steadily expanding the day. To account for that, authorities add a leap second in certain years so that the extra time gets accounted for. This alignment has been deemed necessary for functions like satellite navigation and financial systems. The recent findings are making researchers argue whether a negative leap should be added. It means that a leap second would be removed from the clock to align with sped-up rotation over the last five years.