Earth's rotation is gradually slowing, a process that scientists predict will eventually lead to 25-hour days, though this change is expected to take approximately 200 million years. This lengthening is primarily caused by the Moon's gravitational pull creating tidal friction, which acts as a brake on the planet's spin. Other factors, such as melting ice sheets and shifts within Earth's core, also contribute to subtle fluctuations in rotational speed. These changes are imperceptible on a human timescale and do not affect current timekeeping.