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Glite Dictionary
steradian

steradian

1 9.9
A unit for measuring the size of an area on a sphere from its centre
  • noun
  • /ˈstɛrəˌdeɪən/
  • Specialized
: esteradiano
  • about six steradians

Examples

  • The LAT's field of view exceeds 2.4 steradians.

    Academic text (2012)

  • This is under luminous intensity or Lewins per steradian per Radian steradian.

  • The solid angle of a cone is measured in steradians, which relates to the area and radius of a sphere.

  • For instance, the full solid angle surrounding a sphere is 4π steradians.

  • Astronomers use steradians to describe the size of celestial objects in terms of the solid angles they cover.

Synonyms

sr
vssteradian
  • Specialized
9.9

A unit for measuring how big an area on a sphere looks from its centre

is the full unit name written in words rather than the symbol

Surface Forms

steradian singular
steradians plural

Morphology

steradian = radian (semi-transparent) = ster + radian + ster

Formed by the combining element 'ster-' (meaning 'solid') attached to the technical unit 'radian'; the composition is logical but both elements are specialised, so it is not immediately clear to general learners.

Etymology

Steradian comes from the Greek part stere- meaning 'solid' and from radian, which comes from radius meaning 'ray'. So a steradian is a unit for a 'solid' angle — the three-dimensional angle made by rays from the center of a sphere — and that is why it measures how much area on the sphere those rays cover.