Interesting.

I've always wondered if it was a tad too cutesy for Hank to have known the
date of an otherwise random solar eclipse (observable from locations in
southern Britain) in the 6th century* -- that of course is a literary sort
of question. This time-traveling business is a mess; and sci-fi barely
existed in English when MT sat down to craft this one. You get a few
"gimmies" for these sorts of things, even now.

*His setting is more Malory's than Geoffrey of Monmouth's (Or Nennius's, if
you prefer), of course, but that hardly matters.