90377 Sedna is a trans-Neptunian object currently about three times as far from the Sun as Neptune. For the majority of its orbit it is the most distant known object in the Solar System other than long-period comets. Roughly two-thirds the size of Pluto, Sedna is hypothetically large enough to be rounded by its own gravity, and thus would qualify as a dwarf planet under current definitions. However, its distance makes determining its shape difficult. Spectroscopy has revealed that Sedna's surface composition is similar to that of some other trans-Neptunian objects, being largely a mixture of water, methane, and nitrogen ices with tholins. Its surface is one of the reddest in the Solar System. Its exceptionally long and elongated orbit, taking approximately 12,000 years to complete, and distant point of closest approach to the Sun have led to much speculation as to its origin. Astronomer Mike Brown, who co-discovered Sedna in 2003, believes it to be the most scientifically important trans-Neptunian object found to date, as understanding its peculiar orbit is likely to yield valuable information about the origin and early evolution of the Solar System.
Read the rest of this article: <http://en.wikipedia.org/wiki/90377_Sedna> _______________________________ Today's selected anniversaries: 1910: Aviator Eugene Burton Ely performed the first takeoff from a ship, flying from a makeshift deck on the USS Birmingham in Hampton Roads, Virginia, US. <http://en.wikipedia.org/wiki/Eugene_Burton_Ely> 1940: World War II: Coventry Cathedral and much of the city centre of Coventry, England, were destroyed by the German Luftwaffe during the Coventry Blitz. <http://en.wikipedia.org/wiki/Coventry_Blitz> 1971: NASA's Mariner 9 reached Mars, becoming the first spacecraft to orbit another planet. <http://en.wikipedia.org/wiki/Mariner_9> 1984: Cesar Climaco, mayor of Zamboanga City, the Philippines, was assassinated. <http://en.wikipedia.org/wiki/Cesar_Climaco> 1990: Germany and Poland signed the German–Polish Border Treaty, confirming their border at the Oder-Neisse line, which was originally defined by the Potsdam Agreement in 1945. <http://en.wikipedia.org/wiki/Oder-Neisse_line> _____________________________ Wiktionary's word of the day: legato (adv): (music) Smoothly; in a connected manner <http://en.wiktionary.org/wiki/legato> ___________________________ Wikiquote quote of the day: Call me Ishmael. Some years ago — never mind how long precisely — having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world. It is a way I have of driving off the spleen and regulating the circulation. --Herman Melville <http://en.wikiquote.org/wiki/Herman_Melville> _______________________________________________ Wikipedia Daily Article mailing list. To unsubscribe, visit: https://lists.wikimedia.org/mailman/listinfo/daily-article-l Questions or comments? Contact [email protected]
