an angle excess of 1 radian, to of a complete sphere, or to ≈ 3282.80635 square degrees. The solid angle of a cone whose cross-section subtends the angle is: SI multiples Millisteradians (msr) and microsteradians (μsr) are occasionally used to describe light and particle beams. Other multiples are rarely used. See also n-sphere Spat (angular unit) IAU designated constellations by area References External links Natural units SI derived units Units of solid angle