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2.1.7 Sizing moons

Figure 12 The Moon and Tethys, shown to correct relative scale.

To give you a feel for the sizes of some moons, have a go at the quiz in the next step. There you will see we have provided images of eight moons, but not shown them to scale. All you have to do is guess the correct diameter for each moon (for markedly non-spherical moons we require the length of their long axis). If you get stuck, try consulting the moons data table from Week 1.

These are the moons we have chosen.

  • Enceladus: the sixth-largest moon of Saturn and named after a mythological giant of ancient Greece.
  • Deimos: the outer moon of Mars and named for the Greek personification of terror.
  • Phoebe: thought to have been captured by Saturn’s gravity. It is named after a Titan of Greek mythology who was grandmother to Apollo.
  • Iapetus: the third-largest satellite of Saturn, named after the Titan who fathered Atlas and Prometheus.
  • Tethys: a medium-sized satellite of Saturn, named after a Titan and aquatic sea goddess.
  • Pandora: a satellite of Saturn named after the Greek mythological figure who inadvertently unleashed all the evils of humanity from a jar.
  • Prometheus: a moon of Saturn, named after the Titan who stole fire from the gods. Zeus then condemned him to have his liver eaten daily by an eagle for all time.
  • The Moon: which goes by many names in different cultures; our own name derives from a Proto-Germanic word, mǣnōn.

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