Planetary Science and Astronomical History

A smaller group for concepts about specific planets and the historical development of humanity's model of the solar system, rather than the universe at large or spaceflight engineering: the exoplanets found orbiting other stars, the Van Allen radiation belts trapped by Earth's own magnetic field, and heliocentrism, the model that placed the Sun rather than the Earth at the center of the solar system. Belongs here: a concept tied to a specific planet, a planetary environment, or the history of planetary astronomy. Does not belong here: a concept about the universe's overall origin or structure, grouped under Cosmology and the Early Universe, or about spacecraft mechanics, grouped under Orbital Mechanics and Spaceflight Engineering.