second [s] Unit Converter
Definition of second [s] unit
An arcsecond, often called a second of arc, is an angular unit equal to one-sixtieth of an arcminute and one-3,600th of a degree. It measures very small angles and equals π/648,000 radians, approximately 4.848 microradians.
History of second [s] unit
The term second comes from the sexagesimal subdivision system inherited from ancient Babylonian mathematics, in which units were repeatedly divided by sixty. In medieval and early modern astronomy, a degree was divided into minutes, and each minute into seconds, establishing the arcsecond as a practical fine-angle measure. Astronomers adopted it for describing stellar positions and apparent diameters. Its modern symbol, ″, reflects this tradition. The unit became especially important with telescopic astronomy, precision surveying, geodesy, and, later, astrometry, where tiny positional differences required consistent angular notation.
Applications of second [s] unit
Today, arcseconds are used in astronomy to report stellar coordinates, telescope resolution, planetary positions, and the apparent separation of celestial objects. In geodesy and surveying, they express small changes in latitude, longitude, and direction. Imaging systems may specify angular resolution in arcseconds, while astrophysicists use milliarcseconds or microarcseconds for precise stellar motion and distance measurements.
Complete list of second [s] unit conversion
- millisecond [ms] = 0.001 second [s]
- minute [min] = 60 second [s]
- hour [h] = 3600 second [s]
- day [d] = 86400 second [s]
- week = 604800 second [s]
- month = 2629800 second [s]
- year [y] = 31557600 second [s]
- decade = 315576000 second [s]
- century = 3155760000 second [s]
- millennium = 31557600000 second [s]
- microsecond [µs] = 1.0E-6 second [s]
- nanosecond [ns] = 1.0E-9 second [s]
- picosecond [ps] = 1.0E-12 second [s]
- femtosecond [fs] = 1.0E-15 second [s]
- attosecond [as] = 1.0E-18 second [s]
- shake = 1.0E-8 second [s]
- month (synodic) = 2551442.9 second [s]
- year (Julian) = 31557600 second [s]
- year (leap) = 31622400 second [s]
- year (tropical) = 31556925.216 second [s]
- year (sidereal) = 31558149.763546 second [s]
- day (sidereal) = 86164.090530833 second [s]
- hour (sidereal) = 3590.1704387847 second [s]
- minute (sidereal) = 59.836173979745 second [s]
- second (sidereal) = 0.99726956632908 second [s]
- fortnight = 1209600 second [s]
- septennial = 220903200 second [s]
- octennial = 252460800 second [s]
- novennial = 284018400 second [s]
- quindecennial = 473364000 second [s]
- quinquennial = 157788000 second [s]
- Planck time = 5.391247E-44 second [s]
