Re: Is there a way to see things that the astronauts left on the moon?

Unfortunately not.  Even if the largest item left behind were 5 meters 
across, at the moon's distance of 384,000 kilometers it would subtend only 
some 0.003 arc-seconds.  The atmosphere of the Earth is always somewhat in 
motion, and it turns out this prevents seeing anything below 1 arc-second 
almost all the time, and only very rarely allows 0.25 arc-second of 
resolution. And the Hubble (not limited by atmosphere, of course) does not 
have a big enough mirror (it is about 2.4 meters in diameter) to resolve 
better than roughly 0.06 arc-seconds.

But...

The astronauts did leave behind some corner reflectors, and these can still
be used to bounce radar/radio signals back. This has been used to measure
the very slight changes in the Earth-Moon distance due to tidal 
interactions.