from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A unit of measure equal to the solid angle subtended at the center of a sphere by an area on the surface of the sphere that is equal to the radius squared: The total solid angle of a sphere is 4π steradians. See Table at measurement.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. In the International System of Units, the derived unit of solid angle; the solid angle subtended at the centre of a sphere of radius r by a portion of the surface of the sphere that has area r2. Symbol: sr

from The Century Dictionary and Cyclopedia

  • n. A unit of solid angular measure; the solid angle subtended at the center by that part of a sphere which is equal to the square of its radius, hence by the unit surface on a sphere of unit radius.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the unit of solid angle adopted under the Systeme International d'Unites


ste(reo)- + radian.
(American Heritage® Dictionary of the English Language, Fourth Edition)
ste(reo) + radian (Wiktionary)


  • (c) In photometry, the unit name steradian and the unit symbol sr are usually retained in expressions for derived units.

    International System of Units (SI)

  • Unit of luminous intensity candela The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

    International System of Units (SI)

  • There were some say that this “hole,” which is just a cold spot which has “sharp boundaries” in steradian measure from the surrounding.

    A Dark, Misleading Force

  • A complete steradian sweep showed nothing the size of a spaceship out there.


  • An advantage of the moon over the Earth is that the moon subtends less than 0.25 square degree, whereas the Earth subtends a steradian or more, so scattered light and light potentially leaking around the shutter presents additional problems for the Earth.

    SpaceRef Top Stories

  • More formally, a candela is the intensity of a source that puts out yellow light at 1/683 watt per steradian of solid angle.

    BBC News - Home

  • My follicular kingman homes for sale drowse fractiousness me this scrum to lender inauspiciously his defenseless panicle, his disorganisation to curb, and his steradian for noncausative to mustache.

    Rational Review

  • Flying by the seat of one’s pants, 4-pi steradian shots in the dark, gut checks and the like are all risky in foreign territory.

    Jonathan Wells: Another ID Creationist Who Doesn't Understand Information Theory - The Panda's Thumb

  • k is ~5,000 particles per steradian per square meter per second



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