I’m listening to an old favorite from my adolescence on audiobook these days: H. Rider Haggard’s King Solomon’s Mines. At one perilous point in the story, the hero Allan Quartemain pulls the old “predict an eclipse and frighten the unsuspecting natives into not killing us” trick out of the had. Mark Twain did something similar in A Connecticut Yankee In King Arthur’s Court, and I seem to recall reading about an incident where some real historical character (Marco Polo?) did the same. Haggard used a lunar eclipse while I think Twain used a solar.
Before the advent of computers, how WERE eclipses predicted with such accuracy? A relatively math-free explanation would be most welcome.
BTW-- King Solomon’s Mines is a great adventure story, quite unlike the awful Hollywood versions that have been made. There is some dated colonial stuff which seems dated, but on the whole it’s a lot of fun to read or listen to. Haggard’s other major classic is She, also worth reading.
This NASA site also has some information regarding upcoming solar and lunar eclipses, as well as an upcoming Venus transit: http://eclipse.gsfc.nasa.gov/eclipse.html
Hard to imagine some of the hard number crunchers like Newton doing an algebraical proof of celestial mechanics. Started looking up some stuff on the Mayan calendar and ran across this system of multiplication. Wish they would have done it in base 20.
If he was exploring and checking his position using a sextant or similar, he was likely to have an ephemeris with him: a table of astronomical information, specifically risings and settings and eclipses. Bulky sort of thing. Not a problem if you have native bearers, of course.