Massive moons could potentially support liquid water – and life – even if they orbit a planet located beyond a
star’s habitable zone Extra warmth could come from the reflected light and emitted heat of a host planet, as
well as the planet’s gravitational pull. Just as the Moon raises tides in Earth’s ocean, the gravitational tug of a
gas-giant planet could flex the interior of a nearby moon, pumping it full of frictional heat. Indeed, recent work
by astrophysicists suggests that if a moon orbits too near its gas-giant planet. it could experience so much tidal
heating that it boils off its atmosphere. In wider lunar orbits, the right amount of tidal heating could keep moons
temperate, even if the planet is far from its star.
The passage suggests that which of the following is a factor in the potential habitability of a moon? (Choose all
that apply.)