Expert: Tom Whiting - 1/18/2009

Question
QUESTION: I'm just curious, is there a telescope with which a stargazer could see the U.S. flag which was planted on the moon by NASA?

ANSWER: Hi Dave,
Which flag?... as I believe there are 6 of them (all 6 landings).
No matter.
No, it has to do with resolution; you'd be asking for 5 foot
resolution over 238,000 miles which would, according to laws of
physics, have to have a telescope mirror that's about a mile in diameter; and even then, our atmosphere wouldn't allow for that fine of resolution anyway.  Even on the best nights our atmosphere gives us 0.1- 0.25 arc second resolution, where you're asking like for something 0.0001 arc second resolution for 5 feet/238000 miles.
Our best nights and best scopes can achieve a 1/2 mile wide
crater at 238,000 miles, about 3000 feet resolution at that distance. Hubble could do somewhat better being out in space, but the moon is too bright for Hubble and it would ruin (overwhelm)  all the sensitive detectors which are only designed for very very faint objects, like distant galaxies.
Fortunately,  within the next 10 years, we will have a telescope
camera's in orbit around the moon (primary mission to hunt for
water ice at the polar craters) but as a sidelight, it will be able
to image all the lunar equipment left at the various landing sites at only 30-50 miles in orbit around the moon, as we are currently doing on Mars now. (The Mars orbiters can image the Rovers, just barely).  So it's just a matter of time....and waiting for an orbital camera around the moon.
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA

---------- FOLLOW-UP ----------

QUESTION: Thanks for the fast reply. I see you're in Erie. I live south of you down in Cranberry Township (Butler County) a transplant from Philly. Thanks again

Answer
Hi Dave,
Yes, I have several friends that live in that nice area, since I am
originally from New Castle, PA, not far from that region, and
served on the Boy Scout Staff at Camp Agawam near Prospect, PA....a long time ago.
BTW, something we CAN see on the moon, at least indirectly, are
the laser reflectors left by the astronauts. We routinely still
use them to achieve a plus or minus 1 centimeter exact distance to the moon, which without those laser reflectors, we couldn't do to that high precison distance measurement. And thanks for the nice comments.
Clear Skies,
Tom in Erie.