We generally assume that the closest things to a fire are the hottest, and those farthest away are the coldest. When we map this intuition onto the solar system, we expect Mercury to be uniformly baked and Jupiter to be a frozen ball of gas. Yet the reality of our planetary neighborhood is far more complex. This episode explores how a world's temperature is not simply dictated by its distance from the Sun, but by its own local physics, geometry, and history.

We look at how Mercury's nearly zero axial tilt creates permanently shadowed craters at its poles, preserving ancient water ice despite the planet's scorching equator. We also examine how Jupiter generates nearly twice as much heat as it receives from the Sun through the slow gravitational contraction of its massive interior. These examples reveal that planets are not passive rocks heat ...