© 1994, Astronomical Society of the Pacific, 390 Ashton Avenue,
San Francisco, CA 94112. by George Musser, Astronomical Society
of the Pacific Convection in a pot. The flames under the pot
heat the water on the bottom. As the water gets hotter, it
expands and rises. The colder water above it sinks down to the
bottom, where it too starts to get hot. The process continues
until you shut the stove off. The convection cycle distributes
the heat of the stove evenly throughout the water in the pot. A
primer on convectionStars do it, icy moons do it, even pots of
coffee do it. From the small to the large, things undergo
convection. Convection -- the movement of heat by the movement
of matter -- is a recurring theme in science, and a vivid
reminder that astronomical objects aren't really so different
from everyday objects. They may be bigger and hotter and farther
away, but the same laws of physics determine how they behave.
Convection is a consequence of the most basic drive in nature:
Hot things want to cool down.