In the era of the dinosaurs, a day only lasted 23 hours. (Photo: Hindustan Times)
JAKARTA – The consensus so far is that a day consists of 24 hours. However, the results of the latest research may change that.
Calculating the length of a day on Earth depends on rotation. Because the Earth is not a solid mass but also consists of liquid, its rotation accelerates and slows down depending on the dynamics of the shift.
To understand changes in the Earth’s rotation, scientists at the Technical University of Munich created a machine called a ring laser to accurately measure the length of a day. The implications apparently go far beyond adding and subtracting seconds.
“Fluctuations in rotation are not only important for astronomy, we also really need them to create accurate climate models and better understand weather phenomena like El Nino. And the more accurate the data, the more accurate the predictions,” said Ulrich Schreiber, project leader at the Technical University of Munich quoted from Popular Mechanics, Wednesday (29/11/2023).
Located at the Wettzell Geodetic Observatory, the device uses a ring laser gyroscope and a 13.1-foot-wide track, all contained within a pressurized chamber embedded in the ground approximately 20 feet. This calibration means the device’s laser is only affected by small perturbations of Earth’s rotation.
The device uses a complex system of lasers and mirrors to accurately record the Earth’s rotation; the large difference between the two laser frequencies means the Earth is spinning faster. For example, at the equator, the Earth moves 15 degrees every hour. According to the ring laser of the Technical University of Munich, this latitude produces 348.5 Hz. And every day, this number fluctuates by only about 1 to 3 million Hertz.
However, even with this super-advanced technology, precise measurement of day length is difficult. Precise measurements are only possible when the waveforms of two oppositely directed laser beams are nearly identical. However, device design means there is an ever-present amount of asymmetry.
Over the past four years, geodesists have used theoretical models for laser oscillations to successfully capture these systematic effects to the extent that they can be precisely calculated over long periods of time and thus eliminated from measurements.
With this corrective algorithm, Technical University of Munich scientists were able to measure a day on Earth to nine decimal places, which is equivalent to about one tenth of a millisecond per day. It turns out that the Earth’s rotation fluctuates by about 6 milliseconds every two weeks.
As time goes by, the length of the day on Earth only gets longer. When dinosaurs roamed the Earth, for example, a day lasted only 23 hours. Then 1.4 billion years ago, it only lasted 18 hours 41 minutes. And in 200 million years, a day will last 25 hours.