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History Of The Measurement Of Time by Mind Map: History Of
The
Measurement
Of Time
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History Of The Measurement Of Time

time measurement devices

Sundial,An Egyptian device dating to c.1500 BC

pyramids

The hourglass

One of the earliest clocks was invented by Pope Sylvester II in the 990s.

Electric clocks came into being after 1850

horology

Definitions and standards

The SI base unit for time is the SI second.

The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

larger units such as the minute, hour and day are defined, though they are "non-SI" units because they do not use the decimal system, and also because of the occasional need for a leap second

Chronology

Another form of time measurement consists of studying the past. Events in the past can be ordered in a sequence (creating a chronology), and can be put into chronological groups (periodization). One of the most important systems of periodization is geologic time, which is a system of periodizing the events that shaped the Earth and its life. Chronology, periodization, and interpretation of the past are together known as the study of history.

World time

International Atomic Time (TAI)

Coordinated Universal Time (UTC)

Greenwich Mean Time (GMT)

Universal Time (UT)

Religion

Linear and cyclical time

Numeric and Divine time

calendar

Lunar calendars were among the first to appear, either 12 or 13 lunar months (either 346 or 364 days).

The reforms of Julius Caesar in 45 BC put the Roman world on a solar calendar.

Sidereal time

Sidereal time is the measurement of time relative to a distant star (instead of solar time that is relative to the sun). It is used in astronomy to predict when a star will be overhead. Due to the rotation of the earth around the sun a sidereal day is 4 minutes (1/366th) less than a solar day.