Ribbon World is a phrase coined by Isaac Asimov to describe a non-rotating planet or planet with a tidally locked rotation in which one side of the planet always faces the star that it orbits and another side always faces away. The presumed result is a narrow band or ribbon that may be habitable. However it is possible that climatic extremes would be tempered by thermal recirculation as wind and water carry warmed and chilled air and water across the boundaries betwen the sunward and opposite sides of the planet. A nonrotating planet might actually have more efficient thermal recirculation because there would be no Coriolis effect forcing winds and currents to move nearly perpendicular to thermal gradients as on Earth, rather than in a straight downgradient.

Mercury was long thought to be a tidally locked planet. "The Energy Thief," television episode #90 of Space Patrol, which aired on September 13, 1952, is set in the "twilight belt" of Mercury. Larry Niven's 1964 short story "The Coldest Place" was set on "the coldest place in the Solar System," which readers would assume to be Pluto, only to discover in the end that the actual location is the dark side of Mercury. The story was published just after the planet was found to actually rotate in a 2:3 resonance.

In Wil Mccarthy's novel Lost in Transmission, the planet Gammon flips from one side to the other every 800 years.


  • Dunuos II a.k.a. Hraggellon - John Morressy's Frostworld and Dreamfire
  • Dytallix B a.k.a. Mira V - "Conspiracy," Star Trek: The Next Generation Episode 24, Season 1, 5-9-1988
  • Gammon - Wil McCarthy's Lost in Transmission, p. 368
  • Hraggellon a.k.a. Dunuos II - John Morressy's Frostworld and Dreamfire
  • Mira V a.k.a. Dytallix B - "Conspiracy," Star Trek: The Next Generation Episode 24, Season 1, 5-9-1988
  • Marmora II - A.E. Van Yogt and E. Mayne Hull's Planets for Sale
  • Radole - Isaac Asimov's Foundation and Empire, p. 127
  • Ryloth - Star Wars universe


In Poul Anderson's "Iron," a novella in Larry Niven's Man-Kzin Wars, the planet Prima presents partial rotational lock. See pages 93-94.


{seeded from SuperNova wiki}