Spat… not the usual way.

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Spat… not the usual way.

On June 21, 2009, Posted by , In maths, With 1 Comment


At least that’s what I thought when I read the disambiguation page at Wikipedia, since I only knew the fourth meaning. But as you will be able to guess I wasn’t looking for the past tense of ‘spit’, but the first meaning of the word (the astronomical unit).

It’s funny how we, in our internet search strategy find other words and meanings to old known ones. In my case, the question I wanted to sort out was the number of degrees a sphere had (if a circle has 360). The obvious route has been the sphere (and its Greek root, ‘sphaira’), the ‘solid angle‘ (equivalent on a 3D for the 2D angle), and their unit of measure (the ‘steradian’, equivalent to the 2D ‘radian’).


By the way, ‘Ask Dr. Math‘: the answer is ‘4 pi steradians’ (equivalent in a sphere to 360 degrees in a circle).