wrote in news:1108941878.780319.37180
@z14g2000cwz.googlegroups.com:


What are the limits? Could a 100m diameter optical telescope be built?
what would it see?

Here's a project for a ground-based 100 meter telescope (that's about
328 feet!).

http://www.eso.org/projects/owl/

High angular resolution can be, and is being, achieved with arrays
of optical telescopes. This is probably more practical than a
mirror of some arbitrary maximum size. The OWL barely looks practical
at all.

--Damon