planete

Planète is the French word for a planet. In astronomy, a planet is a celestial body that orbits a star, is massive enough for gravity to give it a nearly round shape, and has cleared its orbital neighborhood of other debris. In 2006, the International Astronomical Union defined three criteria for solar-system planets: it must orbit the Sun, be in hydrostatic equilibrium, and have cleared its orbit; bodies that fail the last criterion are classified as dwarf planets. Exoplanets are planets that orbit stars other than the Sun and are discovered around other stars.

The Solar System includes eight recognized planets, categorized as terrestrial (Mercury, Venus, Earth, Mars) and giant planets (Jupiter, Saturn) and ice giants (Uranus, Neptune). Planets form from the residual gas and dust of a young star’s protoplanetary disk, through accretion of solids and, for gas giants, rapid gas capture. Their properties vary widely: size, mass, density, atmospheric composition, magnetic fields, and potential surface conditions. A planet’s position relative to its star determines its surface temperature and potential habitability, with the habitable zone representing the region where liquid water could exist on a world’s surface.

The term planète derives from Greek planētēs, wanderer, via Latin and French as planète. In English, the same term evolved to planet, retaining the same root. Today, the study of planets spans our own solar system and thousands of known exoplanets, revealing diverse planetary systems.