The Solar System: An Overview (Astronomy)

Recall cards introducing the solar system as a whole. Its inventory: the Sun, the eight planets, their moons and rings, and debris such as asteroids, comets, and dust, formed together about 4.5 billion years ago. The layout: the Sun holding 99.8 percent of the mass, the terrestrial versus jovian planets, distances in astronomical units and orbital periods, densities, and rotations. The smaller bodies: trans-Neptunian objects, the five dwarf planets, moons from the Galilean satellites to Titan and Triton, ring systems, asteroids, comets, meteors, and meteorites. Composition and structure: the hydrogen-rich giants, silicate-and-iron terrestrials, differentiation, and how surface temperature falls with distance. Dating surfaces by crater counts and by radioactive decay, with the major parent-daughter isotope pairs and their half-lives. And the origin of the solar system from a spinning solar nebula of gas and dust.