Timekeeping Timeline |
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Timekeeping Timeline Clock History - Clock Timeline 3500 BC to 2000 AD ![]() |
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![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Technology development that is in the works The Ultra-miniature Rubidium (Rb) Atomic Clock, 40 cubic centimeters in volume and using a minuscule one watt of power, doesn't weigh much more than a matchbox either. And it will lose only about one second every 10,000 years !!! @K6XF |
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. The Moon has a spin of 27.3 days which exactly coincides with one orbit around the Earth. This is the reason that we see the same face of the moon all the time, we never see the back side of the moon. That is because the Moon is in synchronous rotation with the Earth. The Moon rotates on its own axis one time every 27.3 days. The Moon takes 27.3 days to orbit the Earth one time, this is known as a sidereal month. The Moon takes 29.5 days to return to the same point on the celestial sphere (stars) as referenced to the Sun because of the motion of the Earth around the Sun is known as a synodic month (moon-th). 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 moving around the Milky Way Galaxy? about 155 miles/sec - 250 km/sec How fast is our Milky Way Galaxy moving through space? about 185 miles/sec - 300 km/sec |
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© All right reserved 1997 - 2011
This Cummings & Lucas
website created and published by
(Floyd) Ernie Cummings
Timekeepingsite.org
History of Timekeeping
© Bow Wave of Time
--- by Floyd E.Cummings ---
all rights reserved 2011
We are riding on the razor edge bow-wave of Time,
The past just fell behind us,
The present is only a microsecond and
It just ended,
The future is at hand.