Planet

A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity. The term planet is ancient, with ties to history, astrology, science, mythology, and religion. As of 1 December 2020, 4,379 known extrasolar planets in 3,237 planetary systems have been discovered.

About Planet in brief

Summary Planet A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity. The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Apart from Earth itself, five planets in the Solar System are often visible to the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union officially adopted a resolution defining planets. This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit. Some celestial bodies, such as Ceres, Pallas, Juno and Vesta, and Pluto, that were once considered planets by the scientific community, are no longer viewed as planets under the current definition of planet. The idea of planets has evolved over its history, from the divine lights of antiquity to the earthly objects of the scientific age. The concept has expanded to include worlds not only in the solar System, but in hundreds of other extrasolar systems. As of 1 December 2020, 4,379 known extrasolar planets in 3,237 planetary systems have been discovered. Around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone. More than 100 planets are the same size as Earth, nine of which are at the same relative distance from their star as Earth from the Sun, i.

e. in the circumstellar habitable zone of the Sun. Several thousands of planets around other stars have been found in the Milky Way. A 2012 study, analyzing gravitational microlensing data, estimates an average of at least 1.6 bound planets for every star in the galaxy. In ancient times, astronomers noted how certain lights across the sky moved, as opposed to the stars which maintained a constant position in the sky. Ancient Greeks called these lights simply πλάξΝ or simply υξἉΝ. In Greece, China, Babylon, and indeed all pre-modern civilizations, it was almost universally believed that Earth was the center of the Universe and all the planets circled Earth and appeared to revolve around each other each day. The word planet was derived from which today’s word was derived: “planets” or simply “ῆαιξ” or “planet” In order of increasing distance from the sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planet are orbited by one or more natural satellites, and six of the Planetesimals are orbite by a natural satellite. The ambiguities inherent in defining planets have led to much scientific controversy. The IAU definition of a planet is that it is a body that orbits a star.