Moons of giant planets may represent an alternative to the classical picture of habitable worlds .
They may exist within the circumstellar habitable zone of a parent star , and through tidal energy dissipation they may also offer alternative habitable zones , where stellar insolation plays a secondary , or complementary , role .

We investigate the potential extent of stable satellite orbits around a set of 74 known extrasolar giant planets located beyond 0.6 AU from their parent stars - where moons should be long-lived with respect to removal by stellar tides .
For this sample , the typical stable satellite orbital radii span a band some \sim 0.02 AU in width , compared to the \sim 0.12 - 0.15 AU bands for the Jovian and Saturnian systems .
Approximately 60 % of these giant planets can sustain satellites or moons in bands up to \sim 0.04 AU in width .
For comparison , the Galiean satellites extend to \sim 0.013 AU .
We discuss how the actual number and characteristics of satellites will depend strongly on the formation pathways .

We investigate the stellar insolation that moons would experience for these exoplanet systems , and the implications for sublimation loss of volatiles .
We find that between 15 and 27 % of all known exoplanets may be capable of harboring small , icy , moons .
In addition , some 22-28 % of all known exoplanets could harbor moons within a “ sublimation zone ” , with insolation temperatures between 273 K and 170 K. A simplified energy balance model is applied to the situation of temperate moons , maintained by a combination of stellar insolation and tidal heat flow .
We demonstrate that large moons ( > 0.1 M _ { \oplus } ) , at orbital radii commensurate with those of the Galilean satellites , could maintain temperate , or habitable , surface conditions during episodes of tidal heat dissipation of the order 1-100 times that currently seen on Io .