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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).
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 ...
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 ...
Mean solar time was a time standard used especially at sea for navigational purposes, calculated by observing apparent solar time and then adding to it a correction, the equation of time, which compensated for two known irregularities in the length of the day, caused by the ellipticity of the Earth's orbit and the obliquity of the Earth's ...
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 ...
In terms of Earth's rotation, the average day length is about 360.9856°. A day lasts for more than 360° of rotation because of the Earth's revolution around the Sun. With a full year being slightly more than 360 days, the Earth's daily orbit around the Sun is slightly less than 1°, so the day is slightly less than 361° of rotation.
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.