Flag of Mars "red Mars and two moons in blue field above a diagonal, white below". In Robert A. Heinlein's 1961 science-fiction novel "Stranger in a Strange Land", a flag of Mars is hastily improvised, consisting of "the field in white and the sigil of Mars in red". In The Expanse television series, based on "The Expanse" series of novels by James S. A. Corey, the Martian Congressional Republic is the governing body that rules over the inhabitants of Mars and is one of the two human superpowers in the series. Its flag is reminiscent of Mars and its two moons, Phobos 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