Earth's Day Length Could Reach 60 Hours Without the Sun's Influence on the Atmosphere

A team of astrophysicists from the University of Toronto has discovered that the slow and steady lengthening of Earth's day, caused by tidal forces from the Moon, has been halted for over a billion years. The university's website reports this finding.

The scientists concluded that from approximately two billion years ago to 600 million years ago, atmospheric tides resulting from the Sun's influence counteracted the Moon's effect, which slows down the planet's rotation. As a result, the rotation speed remained constant, and the day's duration remained stable at 19.5 hours.

Without this pause in the planet's rotation slowdown for 1.4 billion years, our current 24-hour day would now be over 60 hours long.

The current length of Earth's day is slightly less than 24 hours, specifically 23 hours and 56 minutes. However, the research has shown that the Moon has a much stronger influence on our planet than the Sun. Interestingly, the Moon increases the duration of the day by slowing down Earth's rotation, and without the Sun's influence, the day would have become significantly longer over time.

Based on geological evidence and the use of atmospheric research tools, scientists demonstrate that the tidal deadlock between the Sun and the Moon resulted from a random but consistent connection between atmospheric temperature and Earth's rotation speed.

This state of affairs allowed our planet to develop stable biological rhythms, which we observe today. Therefore, this factor has positively influenced the development of complex life and large ecosystems.

When the Moon first formed about 4.5 billion years ago, the Earth's day lasted less than 10 hours. However, since then, the Moon's gravitational influence has slowed down our planet's rotation, leading to an increase in the day's duration. Today, this process continues, with the Earth's rotation speed decreasing by approximately 1.7 milliseconds per century.

The Moon slows down the planet's rotation by attracting the Earth's oceans, creating tidal bulges on opposite sides of the planet, which we experience as tides. The Moon's gravitational pull towards these bulges, as well as the friction between tides and the ocean floor, acts as a brake on the Earth's rotation.

"Sunlight also induces atmospheric tides with the same bulges. Solar gravity attracts these atmospheric bulges, creating a torque on Earth. But instead of slowing down Earth's rotation like the Moon, it accelerates it," says Professor Norman Murray, a theoretical astrophysicist from the Canadian Institute for Theoretical Astrophysics (CITA) in the Faculty of Arts and Science.

Throughout most of Earth's geological history, lunar tides have outweighed solar tides by approximately a factor of ten, leading to a slowdown in Earth's rotation speed and lengthening of days.