Imagine flipping through a dusty book from 1726, long before telescopes unveiled the finer secrets of our solar system, and stumbling upon a passage that feels strangely prophetic. In the third voyage of Gulliver’s Travels, Jonathan Swift introduces us to the floating island of Laputa, where eccentric astronomers peer into the cosmos. Among their discoveries are two moons orbiting Mars, complete with detailed descriptions of their distances from the planet and their orbital speeds—remarkably close to the real characteristics of Phobos and Deimos. Here’s the twist: these Martian moons weren’t officially discovered until 1877, 151 years after Swift penned his story, with precise orbital measurements coming even later. How could he have described something unseen for generations?
The text invites us to ponder wild possibilities: was it pure imagination, a hint of visions glimpsed through dreams, a trace of lost ancient knowledge, or even whispers of time travel? The mystery casts a curious shadow across the centuries, sparking endless debate.
Yet, a closer look reveals a more grounded explanation. In Swift’s era, Galileo’s discovery of Jupiter’s moons and the identification of Saturn’s satellites had set a pattern—planets seemed to accumulate moons with distance from the Sun. Swift, with his satirical lens, likely guessed Mars, between Earth and Jupiter, might have two. He made them small and close to explain why they’d escaped earlier notice, aligning their orbits with Kepler’s third law (period² ∝ distance³) for scientific flair. His numbers—3 and 5 Mars diameters, with periods of 10 and 21.5 hours—don’t match perfectly (Phobos is at 1.4 diameters with a 7.7-hour orbit, Deimos at 3.5 with 30.3 hours), but they’re in the right ballpark for a 1726 thought experiment.
This wasn’t prophecy but clever extrapolation, echoed by Voltaire’s similar speculation in 1752’s Micromégas. The alignment with reality is a delightful coincidence, amplifying Swift’s genius. So, while the mystery enchants, it’s ultimately a tribute to his wit, not a cosmic riddle.
