I think the weather, then, was pretty much what it is like now. There would have been far less particulate specks in the air, as we sometimes see after a shower of rain, and so it would have been possible, then, to see much further. Or so we assume.

Here's the link to that Electro-acoustic comedy bit about Avebury - www.davidaspinall.co.uk/mp3/Moon.mp3 - it's 3.2Mb. Major lunar 'standstill' approaching ...