When earth formed about 4.6 billion years ago, it’s day would be about 6 hours long. Today, the average day is about 24 hours long, but it is actually increasing by about 1.7 milliseconds every century (100 years)!! How does that happen?
It is all because of the Moon. The Moon impacts the Earth a lot! It controls the tides and even it’s rotation speed! The Moon slows down the Earth’s rotation by using it’s gravity to pull the oceans to form tides. Those tides are slightly ahead of the Earth’s spinning. The Moon’s gravity, Earth’s tidal waves, and Earth’s rotation create a twisting force that eventually slows down the Earth’s rotation. When the rotation slows down, that means that the days get longer. But, not as long to make a large difference in your day!!