Goldilocks zoneGoldilocks zone
See habitable zone.
Origin of Goldilocks zoneAfter the story of Goldilocks and the Three Bears, in which the young girl Goldilocks enters the bears' house during their absence, tastes their bowls of porridge, and finds one too hot, another too cold, but the last one just right
(plural Goldilocks zones)
So called because, like the third of the three bowls of porridge in the fairy tale Goldilocks, it is neither too hot nor too cold, but just right.