The "proof" needed for the average sceptic will be quite higher and importantly, much more tightly defined, than the proof that would be needed for the average astrologer.
If I were attempting to prove astrology, I would likely attempt it through repetitions of correctly assigning charts to their respective
biography/event-list owners. [This advantages the astrologer, as he can utilize several techniques in the process...both the natal analysis and the advantage of checking for appropriate astrology at events.]
In each repetition, if there are 4 charts/individuals, the chances are:
25% that we assign the 1st chart to the rightful owner...
33% that we assign the next chart to its rightful owner...
50% that we correctly assign the next to last chart...
And of course, if we've made it correctly this far, it's 100% likely we can give the last chart out correctly.
So, the chances of correctly assigning all the charts,
in this iteration, would be 25% * 33% * 50% = 4.1667% probability.
Each time we successfully duplicate that, we are defeating another 4.1667% likelihood.
The odds approach mega-lottery levels pretty quickly...