This should answer your question: http://www.telescopes.com/telescopes/canyouseeobjectsleftbehindonthemoonarticle.cfm http://www.telescopes.com/telescopes/canyo

This should answer your question: http://www.telescopes.com/telescopes/canyouseeobjectsleftbehindonthemoonarticle.cfm http://www.telescopes.com/telescopes/canyouseeobjectsleftbeh... tldr: you would need a 200 meter telescope to see the flag, or a 75 meter 'scope to see the lunar rover. The largest earth bound 'scope is 10meters. The Hubble scope is 2.4m Also goes in to the 'rippling flag' question that someone asked in a different comment below.