Earth's rotation is gradually slowing, extending the length of each day by milliseconds per century. This phenomenon is primarily driven by the Moon's gravitational pull, which creates tidal bulges that act as a brake on Earth's spin. Climate change, through the redistribution of mass from melting ice sheets and groundwater changes, also contributes to this deceleration. While a 25-hour day is a theoretical possibility, scientists estimate it would take approximately 200 million years to occur.