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2 Ps: The approximate time since the Cretaceous-Paleogene extinction event, believed to be caused by the impact of a large asteroid into Chicxulub in modern-day Mexico. This extinction was one of the largest in Earth's history and marked the demise of most dinosaurs, with the only known exception being the ancestors of today's birds.
2.68 microseconds – the amount of time subtracted from the Earth's day as a result of the 2004 Indian Ocean earthquake. [2] 3.33564095 microseconds – the time taken by light to travel one kilometre in a vacuum. 5.4 microseconds – the time taken by light to travel one mile in a vacuum (or radio waves point-to-point in a near vacuum).
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 ...
Precession of the Earth's axis (about every 25,700 years) 10 −11: 10 pHz ~31.71 pHz: Once per millennium 10 −10: 100 pHz ~317.1 pHz: Once per century 10 −9: 1 nanohertz (nHz) ~1 nHz: Once per generation (about every 30 years) ~2.9 nHz: Average solar cycle (about every 11 years) ~3.171 nHz: Once per decade 10 −8: 10 nHz 11.6699016 nHz ...
Many computer systems measure time and date using Unix time, an international standard for digital timekeeping.Unix time is defined as the number of seconds elapsed since 00:00:00 UTC on 1 January 1970 (an arbitrarily chosen time based on the creation of the first Unix system), which has been dubbed the Unix epoch.
The first day of winter for the northern hemisphere of Earth will begin on Dec. 21 at approximately 4:21 a.m., according to the Farmers' Almanac. It marks the time when the Earth's northern axis ...
Such alternative units did not gain any notable acceptance. In China, during the Song dynasty, a day was divided into smaller units, called kè . One kè was usually defined as 1 ⁄ 100 of a day until 1628, though there were short periods before then where days had 96, 108 or 120 kè. [7] A kè is about 14.4 minutes, or 14 minutes 24 seconds.
Stargazers will be treated to a rare treat this month when six planets will "align" in the night sky for an eye-catching planet parade.. Planets always appear along a line known as the ecliptic ...