"odin" wrote in message
...
The only reason I can see for going to a larger diameter is to look at
longer wavelength information. Google on "Arecibo radio telescope".

The amount of light an objective mirror gathers (aka "light gathering
power")
http://www.twcac.org/Tutorials/lightgathering_power.htm
is roughly proportional to its area. More LGP means brighter images and/or
shorter photographic exposures - equivalent to a 'fast' camera lens.


Tom Davidson
Richmond, VA