Asaph Hall's Discovery

In 1727 it was common knowledge that Venus had no moons, Earth one, Jupiter four and Saturn five. So it was to be expected that Mars had two moons. Astronomers are convinced Jonathan Swift's prediction must have been just a lucky guess. After all, what else could it be? At the time there was supposedly no telescope powerful enough to see the moons of Mars. It took another 150 years for Asaph Hall to make the discovery.