Re: stero

[bob@MEGALITH.RATTLESNAKE.COM]

    What does {stero} mean?  The gi'uste gives the English gloss
    as "steradian".  Unfortunately, neither I nor my dictionaries
    know what "steradian" means.

A steradian is a unit of measurement of solid angle, just as a radian
is a unit of measurement of a two-dimensional angle.

A radian is the angle subtended by a unit length on the circumference
of a circle of unit radius (180/pi degrees or about 57 degrees); a
steradian is the solid angle subtended by a unit square on the surface
of a sphere of unit radius.

`Steradian' is a fairly common term and I am surprised to see that my
Webster's Collegiate Dictionary is missing it, too.  My OED, which is
notorious for lacking scientific terms, has a definition but I find
its definition to be hard to understand.

--

    Robert J. Chassell               bob@rattlesnake.com
    25 Rattlesnake Mountain Road     bob@ai.mit.edu
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