Spat (angular unit)
The spat (symbol sp[1]), from the Latin spatium ("space"), is a unit of solid angle.[2][3] 1 spat is equal to 4π steradians[1][3] or approximately 41253 square degrees of solid angle (sequence A125560 in the OEIS).[2] As such, it is the solid angle subtended by a sphere at its center.[2]
The spat (symbol S[4]) is also an obsolete unit of distance used in astronomy.[4][2] It is equal to 1,000,000,000 kilometres (620,000,000 mi; 6.7 au).[4][2]
See also
- Turn (geometry) — the 2D counterpart of the spat, equivalent to 2π radians
References
- ^ a b The Ultimate Online Reference for Engineers. Sunnyvale, California, USA: eFunda Inc. Retrieved 2015-10-19.
- ^ a b c d e Rowlett, Russ (2004). "A Dictionary of Units of Measurement". Chapel Hill: University of North Carolina. Retrieved 2015-10-16.
- ^ a b Glossary » Units » Solid Angle » Spat. Sunnyvale, California, USA: eFunda Inc.
- ^ a b c Nouvelle encyclopédie du monde. Vol. 16. Montréal, Toronto, Paris: Éditions Leland Ltée, Librairie Aristide Quillet. 1962. p. 5426.