For many years, people have used different units of time to measure the length of day and night and the time it takes the Earth to orbit the Sun, or the length of a year.
Over the years, the result has been that a year consists of 365.25 days. Thus, each calendar year consists of 365 days, and every four years, it consists of 366 days. According to recent studies, the speed of the Earth is slowing down due to the friction created by the tides from the Moon. This increases the speed of the Earth’s orbit around the Sun by 1.7 milliseconds per century. This is very small and has no effect on current time measurements.
