From Scientific American:
A new study suggests that, contrary to prevailing wisdom, the temperature of a planet doesn’t always stabilize over time, so hot-blooded worlds may have a hard time holding onto liquid water — even if they reside in the temperate region around their stars known as the “habitable zone.”
“Being in the habitable zone is not sufficient to expect Earth-like planetary evolution,” study author Jun Korenaga, a geophysicist at Yale University, told Space.com. “Even if you place a planet with the Earth-like chemical composition — the right amount of water, and so on — it may not evolve Earth-like if it started out too hot or too cold.” [10 Exoplanets That Could Host Alien Life]
For the past 60 years, most scientists have assumed that planets generally settle on a “just right” interior temperature.
For example, heat from Earth’s core rises through the mantle and is released through the crust, in a process known as mantle convection. Because mantle convection speeds up as interior temperatures rise, the heat released should more or less equal the heat produced in a planet’s heart, the thinking has gone.
“This is akin to how warm-blooded animals lower their body temperature by sweating,” Korenaga said.
By studying the Earth’s mantle, however, Korenaga found that a planet doesn’t necessarily reach this point of equilibrium,. As computer simulations have improved since the idea was proposed in the 1960s, more realistic modeling of mantle convection has revealed problems with the original theory.
“Mantle convection could self-regulate if it were made of very simple materials, such as corn syrup,” Korenaga said. That’s because simple materials turn over more rapidly than their complex counterparts, allowing self-regulation.
“But the mantle is made of rocks, which are very complicated materials,” he added.
By studying how Earth’s rocks have deformed and how mantle convection has occurred in …