Moons of Mars on the sides of Saturn (later discovered to be its rings), used the anagram "smaismrmilmepoetaleumibunenugttauiras" for "Altissimum planetam tergeminum observavi" ("I have observed the most distant planet to have a triple form"), Johannes Kepler had misinterpreted it to mean "Salve umbistineum geminatum Martia proles" (Hello, furious twins, sons of Mars). Perhaps inspired by Kepler (and quoting Kepler's third law of planetary motion), Jonathan Swift's satire "Gulliver's Travels" (1726) refers to two moons in Part 3, Chapter 3 (the "Voyage to Laputa"), in which Laputa's astronomers are described as having discovered two satellites of Mars orbiting at distances of 3 and
Galilean moons planet Mercury, though only around half as massive. The three inner moons—Io, Europa, and Ganymede—are in a 4:2:1 orbital resonance with each other. Because of their much smaller size, and therefore weaker self-gravitation, all of Jupiter's remaining moons have irregular forms rather than a spherical shape. The Galilean moons were observed in either 1609 or 1610 when Galileo made improvements to his telescope, which enabled him to observe celestial bodies more distinctly than ever. Galileo's observations showed the importance of the telescope as a tool for astronomers by proving that there were objects in space that cannot be seen by