 Comets are sometimes called dirty snowballs because they are a mixture of ices and dust that never formed a planet.  They are as old as the universe.  Comets are invisible except when near the Sun.  When a comet passes by the Sun its nucleus heats up and spews dust and gases into a giant glowing head larger than most planets.

 nucleus : central portion head of the ocmet  coma : similar to a planets atmosphere, made up of heated gases and dust  hydrogen cloud : generated by the nucleus;  dust tail : points back along the path of the comet; contains dust particles  ion tail: points directly away from the sun

 Hale Bopp-Hale Bopp was disvovered in 1995  Shoemaker Levy 9-This comet came in contact with Jupiter and shattered in It hit Jupiter’s surface in  Hyakutake- Yuji Hyakutake discovered in Japan in 1996 with a pair of binoculars.  Halley-Comet Halley is the most famous comet in history. It was named after Edmund Halley, who first predicted its return in 1759.

THE KUIPER BELTTHE OORT CLOUD  Disc-shaped region in the solar system just outside of Neptune.  Much larger and more distant than the Kuiper Belt.  The Kuiper Belt and the Oort Cloud contain the majority of the comets in the universe.

 First mission where a probe lands on a comet  Planned to land on Comet 67P/Churyumov- Gerasimenko  First time a deep-space mission relies on solar energy rather than nuclear energy  Funded by the ESA(European Space Agency)  Was previously planned to land on comet 46 P/Wirtanen but the rockets failed for the mission  Mistaken for an asteroid in 2007.

 Mission Dates  2 Mar 2004 Launch (07:17 UT)  4 Mar st Earth Gravity Assist  25 Feb 2007 Mars Gravity Assist  13 Nov nd Earth Gravity Assist  5 Sep 2008 Asteroid Steins Flyby  13 Nov rd Earth Gravity Assist  10 Jul 2010 Asteroid Lutetia Flyby  22 May 2014 Comet Orbit Insertion  Nov Dec 2015 Comet Escort Mission  10 Nov 2014 Comet Landing

 To help understand the origin and evolution of the Solar System  Look for compounds and elements essential for life including carbon, hydrogen, oxygen, and nitrogen.  Analyze isotopic abundances in comets to determine if water on Earth came from comets in space

 Contour-USA(NASA)  Deep Impact-USA(NASA)  Deep Space 1-USA(NASA)  Galileo-USA(NASA)  Giotto-ESA  ISEE-3/Ice-USA(NASA)  Sakigake-Japan  SOHO-NASA/ESA  Stardust-USA(NASA)  Suisei-Japan  Ulysses-NASA/ESA  Vega 1&2-USSR

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