Would Echo-1 have been visible from lunar orbit?
I don't recall seeing it myself, being to young then, but the 100+ feet diameter
balloon-satellite was as bright, if not brighter than Venus [Magnitude -4]
in earth orbit according to observers in 1960.
But, hypothetically speaking, if the Soviets or Americans had discharged and inflated
a balloon-satellite as large as Echo-1 in Lunar orbit would it have been visible
to the naked eye [Magnitude 5] as it crossed the darkside of the lunar 'disc'?
Jake