Planetary Science

The process by which a planetary body separates into distinct layers of different composition and density, typically forming a dense metallic core, a silicate mantle, and a lighter crust. This occurs when a body is sufficiently heated for materials to become mobile.

The gradual growth of a planetary body through the gravitational accumulation of smaller particles, dust, and planetesimals from the protoplanetary disk. This process built the planets of our solar system over millions of years.

The region around a star where conditions are suitable for liquid water to exist on a planet's surface, given sufficient atmospheric pressure. Also known as the Goldilocks zone, it is a key criterion in the search for potentially life-bearing worlds.

The generation of internal heat within a planetary body due to frictional forces caused by gravitational tidal flexing, typically from a nearby massive body. This mechanism can sustain geological activity even in small, distant worlds.

The region of space surrounding a planet that is dominated by the planet's magnetic field, which deflects charged particles from the solar wind. A strong magnetosphere protects a planet's atmosphere from being stripped away.

The study of planetary bodies by comparing and contrasting their properties, processes, and histories. By examining similarities and differences between worlds, scientists gain insights that would be difficult to obtain from studying any single body in isolation.

A rotating disk of dense gas and dust surrounding a young star from which planets, moons, asteroids, and other bodies eventually form. The composition and temperature gradients within the disk determine the types of planets that can form at different distances.

A form of volcanism in which volatile substances such as water, ammonia, or methane erupt from the interior of an icy body instead of molten rock. This process is found on several moons and dwarf planets in the outer solar system.

The fraction of incoming solar radiation that is reflected by a surface, expressed as a value between 0 (perfectly absorbing) and 1 (perfectly reflecting). Albedo strongly influences a planetary body's surface temperature and energy balance.

A gravitational interaction in which two orbiting bodies exert a regular, periodic influence on each other because their orbital periods are related by a ratio of small integers. Resonances can stabilize or destabilize orbits over long timescales.