Chapter 1
The Goldilocks Problem
The idea of a "habitable zone" is one of the most powerful in modern astronomy, but the moment you look closely at what it actually promises, it starts to come apart in your hands.
Series · Limits of Habitability
Three rocky planets orbit our Sun in the region where liquid water is possible, and only one of them is alive. What separates Earth from Venus and Mars isn't just distance from the star — it's something about the planets themselves, and the search for that something has become one of the sharpest open questions in modern astronomy. This series follows Dr. Michelle Hill, whose research asks how small a planet can be and still hold onto an atmosphere, the fragile envelope that makes everything else possible. Over thirteen episodes, the Limits of Habitability Series traces the story from the founding of the "habitable zone" concept in the 1990s, through Dr. Hill's own catalogs of every known potentially habitable exoplanet, into the geophysics that decides which of those worlds can actually stay alive. Along the way, we take apart some of the field's most persistent assumptions — including one about planetary magnetic fields that most popular science gets wrong. The season closes on Dr. Hill's newly published work, which delivers the first concrete answer to the minimum-planet question, complete with a surprise that overturned her own predictions.
Chapter 1
The idea of a "habitable zone" is one of the most powerful in modern astronomy, but the moment you look closely at what it actually promises, it starts to come apart in your hands.
Chapter 2
Before you can ask which distant worlds are alive, someone has to find them and sort them — and for a decade of her career, that someone was Dr. Michelle Hill.
No episodes in this chapter yet.
Chapter 3
The habitable zone tells you where to look; it doesn't tell you what to look for. Dr. Hill's own newly published research delivers a first, surprising answer to what the smallest habitable world might actually be.