> > From: Godfrey DiGiorgi <[EMAIL PROTECTED]> > A "large parallel cylinder of light" is the same thing as light > coming from an infinitely distant point source. Consider light from > the sun: all rays are parallel at 92 million miles distance, unless > scattered by atmosphere. In the vacuum of space, they are absolutely > parallel. So even though the sun is several hundred times the > diameter of the Earth and is a light source, it is a point light source.
Point of information: 8-) The sun's light rays are not parallel. If they were, then it would appear the same size at whatever distance you saw it. Think of a laser spot from a pointer. Apart from atmospheric diffusion and the flaws of production, the spot should be the same at one foot, one hundred yards or one mile. _Because the sun is so far away_, the light rays are very close to parallel. But they are not. Interesting discussion. Carry on. m ----------------------------------------- Email sent from www.ntlworld.com Virus-checked using McAfee(R) Software Visit www.ntlworld.com/security for more information
