light-second
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The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly (approximately or ).
Key facts
- Unit.image
- Earth and Moon Size and Distance scale - with real-time light speed!.webm
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- The distance between the Earth and the Moon is approximately 1.3 light-seconds
- Unit.quantity
- length
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- SI units
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- astronomical units
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-   
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- imperial/US units
via Wikipedia infobox
Wikidata facts
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- conversion to SI unit
- 299792458
- Wikidata SPARQL query equivalent
- wd:Q909315 p:P2370/psn:P2370 [wikibase:quantityAmount ?source; wikibase:quantityUnit ?base]. ?item p:P2370/psn:P2370 [wikibase:quantityAmount ?target; wikibase:quantityUnit ?base]. BIND(?source / ?target as ?value)
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Article
4 sectionsContents
- Use in telecommunications
- Use in astronomy
- See also
- References
The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly (approximately or ).
Just as the second forms the basis for other units of time, the light-second can form the basis for other units of length, ranging from the light-nanosecond ( or just under one international foot) to the light-minute, light-hour and light-day, which are sometimes used in popular science publications. The more commonly used light-year is also currently defined to be equal to precisely , since the definition of a year is based on a Julian year (not the Gregorian year) of exactly , each of exactly .