How invented the clock

How We Keep Time

Our clock and calendar measure the movement of the Sun, the Moon and the Stars as seen from Earth. That's how mankind keeps time and how we became timekeepers.

A day comes from the rotation of the earth on its axis, which takes about 24 hours, and the time of day comes from the Sun appearing to travel across the sky at about 15 degrees every hour.

The cycles of the Moon's phases is used to measure a Month. The moon takes 29.5 days to return to the same point in the sky, as referenced to the Sun, this is called a synodic month. There are about 7 lunar phases as observed from the Earth.

One year is the time taken for Earth to complete one orbit around the Sun relative to the stars, and is called a sidereal year. However, we measure a year to be the period between two successive spring equinoxes known as the Vernal Equinox and is on or about March 21, and this period is called a tropical year. The tropical year is about 20 minutes shorter than the sidereal year.

How fast is the Earth spinning?
about 1040 miles/hr - 1670 km/hr - 0.5 km/sec

How fast is the Earth revolving around the Sun?
about 18.5 miles/sec - 30 km/sec - 30 km/sec

How fast is the Earth,
along with the Solar System