P3D Re: Stereography of whole planets

[john bercovitz <bercov@xxxxxxxxxxx>]

Paul Talbot wrote:

> To put this in perspective, I have read that the surface of the
> Earth, relative to its size, is smoother than the surface of a
> basketball.
> 
> But I'll leave it to John B. to do the math and tell us if that
> is an accurate analogy or not.  :)

Always a little challenge.  Unforunately, I don't have a basketball.
I would guess it is 300 mm in diameter and its surface roughness 
amounts to about a mm.  That would make the roughness 1/300 of its 
diameter.  I would guess earth's roughness to be 1/5 of that if you
count the surface of the seas as being the surface and not the surface 
of the rock beneath the seas.

John B


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