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| abstraction > mathematical concept > unit > length unit |
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| length unit comparison table | ||||||||||||||||||
| Subject | has accuracy | has consequence | has proposer | is an acronym for | is an instance of | has proposal date | has approval date | has equivalent | has name origin | has unit | has approval agency | has value in SI unit | has uncertainty | has definition | has equation | has symbol | has historical origin | is named after |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| angstrom | non SI unit | 10-10 meters | A unit of length used when expressing wavelengths. | Å | Anders Jonas Angstrom (1814-1874) | |||||||||||||
| astronomical unit | non SI unit | 1 au = 1.49598 × 1011 m, approximately | The radius of a circular orbit in which a body of negligible mass, and free of perturbations, would revolve around the Sun in 2π / k days, where k is the Gaussian gravitational constant. This is slightly less than the semi-major axis of the Earth's orbit. | AU | ||||||||||||||
| Bohr radius | Hartree | radius | 1928 | 0.0000000019 × 10-10 m | A unit of length based on the radius of the first Bohr orbit of hydrogen 1. |  | a0 | Niels Bohr | ||||||||||
| fermi | length unit | 1956 | 10-13 cm | A unit of distance used for describing nuclear distances just as the ångström is used for atomic distances. | Enrico Fermi | |||||||||||||
| light-year | length unit | The distance light travels in a vacuum in 1 year. 1 lt-yr = 9.4605 × 1012 km = 0.307 pc (c = 299792.46 km s-1 = 186274 miles s-1). (1 lt-min ≈ 0.13 AU.) | ly | |||||||||||||||
| meter | fixes the speed of light in vacuum at exactly 299792458 m·s-1 | Syteme Internationale | base SI unit | 1960 | 11th CGPM | length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second | m | chosen in 1791 by the French Academy of Sciences as 10-7 of the length of the meridian through Paris from pole to the equator | ||||||||||
| micron | length unit | 104 Å | A unit of length. | μ | ||||||||||||||
| mile | length unit | The mile employed in this book is the statute mile, equal to 5280 feet. | ||||||||||||||||
| nautical mile | length unit | 1.15 statute miles | A unit of length. | |||||||||||||||
| parsec | Bessel and Meadows | length unit | 1840 | 1922 | 2.062648 × 105 astronomical units | parallax second | International Astronomical Union | The distance at which one astronomical unit subtends an angle of 1 second of arc. 1 pc = 206,265 AU = 3.086 × 1013 km = 3.26 light-years. | pc | |||||||||
| solar radius | radius | length unit | A unit of length based on radius of Sun |
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