What is the smallest distance you can see on the Moon with a telescope?

A telescope with one arc second resolution, at a distance of 350,000 kilometers, can resolve objects that are 1.7 kilometers across. This is about the same size as the limit set by the stability of our atmosphere which causes 'twinkling'.

Large telescopes can take advantage of fleeting moments of atmospheric stability which last less than a second, to get down to about 0.5 arcseconds or 900 meters on the moon. The Hubble Space Telescope, located above the turbulent atmosphere, has a working resolution of 0.04 arcseconds corresponding to 70 meters. This is still way too large to see small things like the Apollo landing module (5 meters) or scientific equipment ( 0.5 meters).

Copyright 1997 Dr. Sten Odenwald