A dwarf planet is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighbouring region of planetesimals and is not a satellite. They are smaller than planets, but more massive than small solar system bodies. The term was adopted in 2006 by the International Astronomical Union (IAU) as a result in the increase in discoveries of trans-Neptunian objects that rivaled Pluto in size, and finally precipitated by the discovery of an even more massive object, Eris. The IAU currently recognizes five dwarf planets—Ceres (pictured), Pluto, Haumea, Makemake, and Eris. It is suspected that at least another 40 known objects in the Solar System are dwarf planets, but the number might be as high as 2,000. The 2006 definition has been both praised and criticized, and has been disputed by some scientists.
Read the rest of this article: <http://en.wikipedia.org/wiki/Dwarf_planet> _______________________________ Today's selected anniversaries: 755: In Tang Dynasty China, An Lushan revolted against Chancellor Yang Guozhong, initiating the An Shi Rebellion, which lasted eight years before it was put down. <http://en.wikipedia.org/wiki/An_Shi_Rebellion> 1497: On his way to India, Vasco da Gama and his crew passed the Great Fish River on the Cape of Good Hope, becoming the first Europeans to sail into the Indian Ocean. <http://en.wikipedia.org/wiki/Vasco_da_Gama> 1689: The Parliament of England adopted the Bill of Rights, declaring that Englishmen possessed certain positive civil and political rights. <http://en.wikipedia.org/wiki/Bill_of_Rights_1689> 1960: United Airlines Flight 826 and Trans World Airlines Flight 266 collided in mid-air in heavy clouds over Staten Island, New York City, killing 134 people. <http://en.wikipedia.org/wiki/1960_New_York_air_disaster> 1997: "Dennō Senshi Porygon", an episode of the Japanese television series Pokémon, induced epileptic seizures in 685 children. <http://en.wikipedia.org/wiki/Denn%C5%8D_Senshi_Porygon> _____________________________ Wiktionary's word of the day: bookish (adj): 1. Given to reading; fond of study; better acquainted with books than with people; learned from books. 2. Characterized by a method of expression generally found in books <http://en.wiktionary.org/wiki/bookish> ___________________________ Wikiquote quote of the day: The only way of discovering the limits of the possible is to venture a little way past them into the impossible. --Arthur C. Clarke <http://en.wikiquote.org/wiki/Arthur_C._Clarke> _______________________________________________ Wikipedia Daily Article mailing list. To unsubscribe, visit: https://lists.wikimedia.org/mailman/listinfo/daily-article-l Questions or comments? Contact [email protected]
