Excess heat is flowing from the north pole of Enceladus, hinting at a careful energy balance deep that may have kept the subsurface ocean stable over geologically significant timescales, boosting its suitability for life.
One of Saturn's moons, Enceladus has been known to be an active ocean world ever since 2005, when the Cassini mission found giant plumes of water vapour squirting up from the ocean deep below through huge fractures in the surface. These plumes are powered by energy from tidal interactions with Saturn, which flex the moon's interior, subtly squeezing and stretching it and ultimately keeping its interior warm enough for liquid water.
