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 In 1959, an American Astrophysicist named Su-Shu Huang introduced the term "habitable zone" in reference to the area around a star where liquid water could exist on a sufficiently large body. The habitable zone is also called the Goldilocks zone, a metaphor of the children's fairy tale of "Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right". The Earth sits “just right” in the habitable zone of our Sun.