Minor bodies of the solar system: Comets and their importance Ramiz Ahmad IIST, Trivandrum
Plan of the talk:•Introduction•Historical view point•Structure of comets•Origin.•Reasons for studying comets•Missions for comets•Conclusion
Introduction:Comets: Dirty Balls of Ice They look like a star with a ghostly white tail. The term "comet" derives from the Greek aster kometes, which means "long- haired star"---a reference to the tail.
Comets: Dirty Balls of Ice•They can be seen by us only when they pass by the sunand the sun’s heat melts them.•The comets tail is made of material from the comet; gasfrom the ices and dust that is mixed in with the ice. Theyescape as the comet melts.•The tail always points away from the sun due to thesolar winds (movement of heat away from sun)
History• The history of comet watching dates back to 1000 BC from the Chinese records and Chaldea, a place in present Iraq.• Comets have been regarded as omen, even as recently as 1986.• Today Astronomer study Comets from scientific perspectives, and our understanding of these fascinating objects have grown tremendously.
• The icy, hard part of the comet is called the nucleus. Asthe comet melts, sometimes large chunks of ice break offin a hurry and large amounts of gases escape at once andcause a bright “outburst”.• The gas and dust are released and form an atmospherearound the comet called the coma.
Importance of studying Comets:• The study of the composition of the comets gives an ideaof the composition of the solar system in the early stages ofthe solar system.•Life on earth is theorized to have been seeded by thecomets. A detailed study will provide with sufficientevidence to either support or reject the theory.
Missions for comets•New Horizons - NASA Pluto and Kuiper Belt mission•Deep Impact/EPOXI - NASA Flyby of CometsP/Tempel 1 and Hartley 2 (2005)•Rosetta - ESA Mission to Comet Churyumov-Gerasimenko (2004)•CONTOUR - NASA Mission to fly by three cometnuclei (2002)•Genesis - NASA Discovery Solar Wind Sample ReturnMission (2001)•Stardust - NASA Discovery Mission to collect samplesfrom Comet P/Wild 2 (1999)
•Deep Space 1 - NASA Flyby Mission to comet Borrellyand asteroid Braille (1998)•Galileo - NASA Mission to Jupiter, imaged CometShoemaker-Levy 9 Impact (1989)•Giotto - ESA mission to Comets Halley and Grigg-Skjellerup•ICE (ISEE-3) - NASA Mission to Comet Giacobini-Zinner•Sakigake - Japanese ISAS mission to Comet Halley•Suisei - Japanese ISAS mission to Comet Halley•Vega 1 - Soviet mission to Venus and Comet Halley•Vega 2 - Soviet mission to Venus and Comet Halley
References:• www.wikipedia.org• Chapman, C. R.; Morrison, D.; Zellner, B. (1975). "Surface properties of asteroids: A synthesis of polarimetry, radiometry, and spectrophotometry". Icarus 25 (1): 104– 130. Bibcode 1975Icar...25..104C.doi:10.1016/0019- 1035(75)90191-8.• http://solarsystem.nasa.gov/• "Lagrange Points" by Enrique Zeleny, Wolfram Demonstrations Project.