Irish angle to Phobos and Deimos.
When Asaph Hall discovered the two moons of Mars in 1877 he named them from this passage from Homer's Iliad:
"Ares (Roman Mars)...summoned Fright and Fear (Phobos and Deimos) to yoke his steed and put his glorious armour on".
However ,writing in Gullivers Travels in 1726, the Dubliner Jonothan Swift wrote that astronomers of Laputa had discovered two moons orbiting Mars.
The quiz question is this:
How did Swift "know" that there were two moons orbiting Mars 151 years before they were discovered? Peter.
Suppose it's a good astronomy pub quiz question but it's being going the rounds for a long long time and there's no great mystery about it. Swift _didn't_ know about Mars's moons - he couldn't have for the very reason you state - they hadn't been discovered. The most likely scenario (there are others) is that Swift based his comments on a mistake by Kepler who misinterpreted a coded message from Galileo to mean that Mars had two moons whereas Galileo was actually referring to the fact that Saturn looked like it had triple form (Galileo couldn't resolve the rings). Swift embellished Kepler's comments and struck lucky! However, his descriptions of the moons' distances from Mars and rotation periods are inaccurate enough that they can only be described as 'reasonably good guesses' presumably based on the assumption that if Mars had moons, they must be small and close to the planet.
  