In an interview with Live Science, Sarah Milholland, an associate professor at MIT, revealed that the duration of a day on Earth has not always been constant. She explained that Earth has experienced periods of shorter and longer days, with the influence of tidal interactions with the moon playing a significant role. Approximately a billion years ago, the day on Earth lasted only about 19 hours.
According to Konstantin Batigin, a professor of planetary sciences at CALTECH, in the early stages of Earth’s history, the day could have been less than 10 hours long. This drastic change is attributed to a massive collision with a protoplanet the size of Mars, which accelerated the Earth’s rotation, leading to the formation of the moon. Over time, the moon’s tidal forces slowed down the Earth’s rotation.
While there have been times when the day on Earth was longer than 24 hours, the difference was only a few milliseconds due to various factors like changes in the molten nucleus, oceans, or atmosphere. Milholland emphasizes that the Earth’s rotation speed is influenced by its formation process, with factors like the location of the planet in the protoplanetary disk impacting its angular momentum.
Currently, the day on Earth continues to change slowly, with its lengthening by approximately 1.7 milliseconds per century, as explained by Batigin. This gradual change allows evolutionary processes to adapt accordingly. The main reason for the Earth’s rotation slowdown is its interaction with the moon, which creates friction and gradually increases the distance between the Earth and its satellite.
In addition to natural factors like earthquakes and asteroid collisions affecting the day’s duration, human activities can also play a role. Milholland points out that climate changes can impact the Earth’s rotation due to mass redistribution from melting glaciers, changing sea levels, and tectonic activity.
Overall, interactions with the moon, natural disasters, and human activities all continue to influence the Earth’s rotation, leading to a gradual slowdown with each passing century.