You can still see it with a small telescope

And sometimes you can just cop out like this: http://archiveofourown.org/works/3606378

(Well, probably not exactly like that, but leaving everything to the reader's imagination. "An interesting silence ensued." etc. etc. If you get really stuck. (Heyer actually tends to end her romances this sort of way, where you don't have a description of the act, you have somebody's reaction to it, but obviously it is often a humorous device.) But can be used in emergencies with little shame!)