planète

Planète is a French term that translates to "planet" in English. In astronomy, a planet is a celestial body that orbits a star or stellar remnant, is massive enough to be rounded by its own gravity, and has cleared its orbit of other debris. The term "planète" is derived from the Greek word "planētēs," which means "wanderer," reflecting the ancient observation that planets appear to move across the sky differently from fixed stars.

The modern definition of a planet was established by the International Astronomical Union (IAU) in 2006. According to this definition, a planet must meet three criteria: it must orbit a star, it must be massive enough for its gravity to make it round, and it must have cleared its orbit of other debris. This definition led to the reclassification of Pluto as a "dwarf planet," as it does not meet the third criterion.

Planètes can be categorized into two main types: terrestrial planets and gas giants. Terrestrial planets, like Earth, are primarily composed of rock and metal, while gas giants, like Jupiter, are composed mostly of hydrogen and helium. Planètes can also be classified based on their location in the solar system, with inner planets being closer to the star and outer planets being farther away.

The study of planète is a fundamental aspect of astronomy, as it helps scientists understand the formation and evolution of planetary systems. By studying the characteristics and behavior of planète, scientists can gain insights into the conditions necessary for the emergence of life and the potential for habitability in other parts of the universe.