Moons of Mars satellites, Earth had one and Jupiter had four (known at the time), that Mars by analogy must have two. Furthermore, as they had not yet been discovered, it was reasoned that they must be small and close to Mars. This would lead Swift to making a roughly accurate estimate of their orbital distances and revolution periods. In addition Swift could have been helped in his calculations by his friend, the mathematician John Arbuthnot. Voltaire's 1752 short story "Micromégas", about an alien visitor to Earth, also refers to two moons of Mars. Voltaire was presumably influenced by Swift. In recognition of
The Angry Red Planet find a recording of an alien voice, which announces that the ship's crew were allowed to leave Mars so they could deliver a message to their home planet. The voice then states that "we of Mars" have been observing human development on Earth for many thousands of years and have determined that humanity's technology has far outpaced progress in cultural advancement. The alien then accuses humankind of invading Mars, warning that if future expeditions ever return to the Red Planet, the Earth would be destroyed in retaliation. "The Angry Red Planet" began as "The Planet Mars", a treatment written by