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Earth Hour is a worldwide movement organized by the World Wildlife Fund (WWF). The event is held annually, encouraging the individuals, communities, and businesses to give an hour for Earth, and additionally marked by landmarks and businesses switching off non-essential electric lights, for one hour from 8:30 to 9:30 p.m., usually on the last Saturday of March, as a symbol of commitment to the ...
An hour (symbol: h; [1] also abbreviated hr) is a unit of time historically reckoned as 1 ⁄ 24 of a day and defined contemporarily as exactly 3,600 seconds . There are 60 minutes in an hour, and 24 hours in a day. The hour was initially established in the ancient Near East as a variable measure of 1 ⁄ 12 of the night or daytime.
The Greenwich 24-hour analog clock at 14:06:49 UTC. The hour hand is at an angle of 211° 42′ 15″ from vertical, making the time 211° 42′ 15″ in NET. An example New Earth Time analog clock. New Earth Time (or NET) is an alternative naming system for measuring the time of day proposed in 1999. In NET the day is split into 360 NET ...
Earth-based: the day is based on the time it takes for the Earth to rotate on its own axis, as observed on a sundial [citation needed]. Units originally derived from this base include the week (seven days), and the fortnight (14 days). Subdivisions of the day include the hour (1/24 of a day), which is further subdivided into minutes and seconds ...
The planetary hours are an ancient system in which one of the seven classical planets is given rulership over each day and various parts of the day. Developed in Hellenistic astrology, it has possible roots in older Babylonian astrology, and it is the origin of the names of the days of the week as used in English and numerous other languages.
The commission proposed making the standard hour the base unit of metric time, but the proposal did not gain acceptance and was eventually abandoned. [ 11 ] When the modern SI system was defined at the 10th General Conference on Weights and Measures (CGPM) in 1954, the ephemeris second (1/86400 of a mean solar day) was made one of the system's ...
1/31 556 925.9747 = 129 602 768.13 / (360×60×60×36 525×86 400). Caesium atomic clocks became operational in 1955, and quickly confirmed the evidence that the rotation of the Earth fluctuated irregularly. [32] This confirmed the unsuitability of the mean solar second of Universal Time as a measure of time interval for the most precise purposes.
A geographical mile is defined to be the length of one minute of arc along the equator (one equatorial minute of longitude) therefore a degree of longitude along the equator is exactly 60 geographical miles or 111.3 kilometers, as there are 60 minutes in a degree. The length of 1 minute of longitude along the equator is 1 geographical mile or 1 ...