Ten Planets: Stories

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This definition has not been universally used or accepted. In planetary geology, celestial objects have been assessed and defined as planets by geophysical characteristics. Planetary scientists are more interested in planetary geology than dynamics, so they classify planets based on their geological properties. A celestial body may acquire a dynamic (planetary) geology at approximately the mass required for its mantle to become plastic under its own weight. This leads to a state of hydrostatic equilibrium where the body acquires a stable, round shape, which is adopted as the hallmark of planethood by geophysical definitions. For example: [57] a b Schneider, Jean (July 2016). "Exoplanets versu Ronan, Colin (1996). "Astronomy Before the Telescope". In Walker, Christopher (ed.). Astronomy in China, Korea and Japan. British Museum Press. pp.264–265.

The native Persian names of most of the planets are based on identifications of the Mesopotamian gods with Iranian gods, analogous to the Greek and Latin names. Mercury is Tir (Persian: تیر) for the western Iranian god Tīriya (patron of scribes), analogous to Nabu; Venus is Nāhid ( ناهید) for Anahita; Mars is Bahrām ( بهرام) for Verethragna; and Jupiter is Hormoz ( هرمز) for Ahura Mazda. The Persian name for Saturn, Keyvān ( کیوان), is a borrowing from Akkadian kajamānu, meaning "the permanent, steady". [97]a b Emery, J. P.; Wong, I.; Brunetto, R.; Cook, J. C.; Pinilla-Alonso, N.; Stansberry, J. A.; Holler, B. J.; Grundy, W. M.; Protopapa, S.; Souza-Feliciano, A. C.; Fernández-Valenzuela, E.; Lunine, J. I.; Hines, D. C. (26 September 2023). "A Tale of 3 Dwarf Planets: Ices and Organics on Sedna, Gonggong, and Quaoar from JWST Spectroscopy". arXiv: 2309.15230 [ astro-ph.EP]. The first confirmed discovery of an extrasolar planet orbiting an ordinary main-sequence star occurred on 6 October 1995, when Michel Mayor and Didier Queloz of the University of Geneva announced the detection of 51 Pegasi b, an exoplanet around 51 Pegasi. [164] From then until the Kepler mission most known extrasolar planets were gas giants comparable in mass to Jupiter or larger as they were more easily detected. The catalog of Kepler candidate planets consists mostly of planets the size of Neptune and smaller, down to smaller than Mercury. [165] [166]

Brown, Michael E. "The Dwarf Planets". California Institute of Technology, Department of Geological Sciences . Retrieved 26 January 2008. Ceres, a round object in the Asteroid Belt between Mars and Jupiter, also got the boot. Ceres was considered a planet when it was discovered in 1801, but it was later deemed to be an asteroid. That still didn't quite fit because it was so much larger (and rounder) than the other asteroids. Astronomers instead deemed it a dwarf planet in 2006, although some astronomers like to consider Ceres as a 10th planet (not to be confused with Nibiru or Planet X). The Hubble Space Telescope captured this image of Saturn during its northern hemisphere summer on July 4, 2020. (Image credit: NASA, ESA, A. Simon (Goddard Space Flight Center), M.H. Wong (University of California, Berkeley), and the OPAL Team)

Past the Kuiper Belt is the very edge of the solar system, the heliosphere, a vast, teardrop-shaped region of space containing electrically charged particles given off by the sun. Many astronomers think that the limit of the heliosphere, known as the heliopause, is about 9 billion miles (15 billion km) from the sun. Bausani, Alessandro (1973). "Cosmology and Religion in Islam". Scientia/Rivista di Scienza. 108 (67): 762. a substellar-mass body that has never undergone nuclear fusion and has enough gravitation to be round due to hydrostatic equilibrium, regardless of its orbital parameters. [58]