Wikipedia:Today's featured article/June 18, 2024
A planet is a large, rounded astronomical body that is neither a star nor a stellar remnant. The archetypal examples are eight planets in the Solar System: the four terrestrials Mercury, Venus, Earth, and Mars, and the four giant planets Jupiter, Saturn, Uranus, and Neptune. The term was initially used to denote the Sun, the Moon, and the five naked-eye planets that move across the background of the stars: they historically were seen as having associations with the gods. As scientific knowledge advanced, human perception of the planets changed. Copernicus suggested that the planets orbited the Sun and that the Earth was itself a planet, and the development of the telescope led to a broadening of the definition to accommodate other discoveries within and beyond the Solar System. Many extrasolar planets display features unseen in the Solar System. The International Astronomical Union defines a planet in the Solar System to have cleared its neighbourhood of other bodies, and that extrasolar planets should orbit stars and not be large enough to support deuterium fusion; however, many planetary scientists continue to apply the word "planet" more broadly, including dwarf planets, planetary-mass moons, rogue planets, and brown dwarfs. (Full article...)