Ammon – Clocks tell us that a full day on Earth lasts 24 hours, or 1,440 minutes, or 86,400 seconds. But this number is neither accurate nor stable.
The exact length of a day on Earth depends on how long it takes our planet to complete one revolution, which often changes very slightly, thanks to dramatic events, such as earthquakes and volcanic eruptions, as well as more subtle shifts caused by the liquid metal in the Earth’s outer core that orbits around it. Solid inner core.
Scientists say that these millisecond-level disturbances are small and cannot be predicted, but measuring them is useful for science.
“Fluctuations in circulation are not only important for astronomy, we also urgently need them to create accurate climate models and better understand weather phenomena such as El Niño,” explained Ulrich Schreiber, a professor at the Technical University of Munich (TUM) in Germany. He added that in the current situation, “the more accurate the data is, the more accurate the forecasts are.”
Schreiber and his colleagues measured these very subtle changes in day length with unprecedented precision. They used a rotating laser ring gyroscope, which is a 4-meter (13.1-foot) wide “racetrack” located in a pressurized chamber at the Geodetic Observatory Wettzell facility in Germany.
The device is placed in the rock at a depth of 6 meters (19.6 feet), so the laser beams are affected only by changes in the Earth’s rotation and not by other environmental factors, according to the research team.
The gyroscope features two laser beams, one moving clockwise and the other counterclockwise.
If the Earth were perfectly balanced, both rays would travel the same distance. But the device is subject to the same oscillations as the Earth, so one laser beam covers a slightly smaller distance than the other.
By accounting for this variation, Schreiber and his colleagues found that our planet’s rotation changes little over time, fluctuating by up to 6 milliseconds over periods lasting a few weeks or so. Despite these results, it remains true that a day on Earth is about 24 hours long.
They report their findings in a paper published in the journal Nature Photonics. In the coming months, the team plans to further improve the laser gyroscope, so that it provides more accurate measurements.
“RT”
