Unraveling the Mystery of Earth's 24-Hour Day and the Sun's Role

The length of Earth's day is 24 hours due to a balance between the gravitational tidal forces from the moon and the sun. The moon's gravity pulls on Earth's oceans, resulting in high tides that slow down Earth's rotation, while thermal tides in Earth's atmosphere speed up the rotation. For a long period between 2.2 billion and 600 million years ago, the thermal tides and lunar tides were in sync, keeping Earth's day length at 19.5 hours. However, over the past 600 million years, Earth's rotation has been slowing down again. Climate change could further disrupt this balance, leading to longer days.