1. BY: IAN + SHAE

2. What is a Comet? Small solar system body Small solar system body Displays coma (a thin, fuzzy, temporary atmosphere) when close enough to the sun Displays coma (a thin, fuzzy, temporary atmosphere) when close enough to the sun Few kilometers across, and appear to mostly be composed of water, carbon dioxide, ammonia, and methane ices, with dust mixed in Few kilometers across, and appear to mostly be composed of water, carbon dioxide, ammonia, and methane ices, with dust mixed in Observed since ancient times Observed since ancient times

4. Parts of the comet Coma Coma cloud of diffuse material surrounding the comet, cloud of diffuse material surrounding the comet, usually grows in size and brightness as the comet approaches the Sun.usually grows in size and brightness as the comet approaches the Sun. Nucleus Nucleus small, bright (less than 10 km in diameter)small, bright (less than 10 km in diameter) visible in the middle of the comaThe coma and the nucleus together constitute the head of the cometvisible in the middle of the comaThe coma and the nucleus together constitute the head of the comet

5. Continued… Dust Tail Dust Tail composed of dust particles liberated from the nucleus as the ices are vaporizedcomposed of dust particles liberated from the nucleus as the ices are vaporized Ion Tail Ion Tail composed of ions blown out of the comet away from the Sun by the solar windcomposed of ions blown out of the comet away from the Sun by the solar wind

6. Cometary Orbits Most comets have elongated elliptical orbits get close to the sunand then out into the further reaches of the Solar System Most comets have elongated elliptical orbits get close to the sunand then out into the further reaches of the Solar Systemelliptical orbitselliptical orbits Classified according to the length of their orbital periods: the longer the period the longer the ellipse Classified according to the length of their orbital periods: the longer the period the longer the ellipseorbital periodsorbital periods

7. Continued.. Short-period comets less than 200 years, orbit in the ecliptic plane, same direction as the planets Short-period comets less than 200 years, orbit in the ecliptic plane, same direction as the planets Short-period cometsecliptic Short-period cometsecliptic Long-period comets have highly eccentric orbits and periods ranges from hundreds to millions of years Long-period comets have highly eccentric orbits and periods ranges from hundreds to millions of yearseccentric Single-apparition comets similar to long- period comets, but have parabolic or slightly hyperbolic trajectories Single-apparition comets similar to long- period comets, but have parabolic or slightly hyperbolic trajectoriesparabolic hyperbolicparabolic hyperbolic

8. Oribital Periods Orbits range from a few years to thousands of years Orbits range from a few years to thousands of years Short period comets are from Kuiper belt Short period comets are from Kuiper belt Long period comets are from Oort Cloud due to gravitation Long period comets are from Oort Cloud due to gravitation

9. Comet Halley Seen from Earth every 75 years Seen from Earth every 75 years Short period comet Short period comet gravitational pull of the major planets alters the orbital period from revolution to revolution. gravitational pull of the major planets alters the orbital period from revolution to revolution. nucleus is around 16x8x8 kilometers nucleus is around 16x8x8 kilometers

10. ORIGIN OF WATER One theory of where water came from is that comets from space brought water to earth This theory is plausible because one of the components of comets is ice

11. Interesting facts Many scientists believe that comets brought the vast quantities of water that now fill the Earth's oceans Many scientists believe that comets brought the vast quantities of water that now fill the Earth's oceans July 1994 when Comet Shoemaker-Levy 9 broke up into pieces and collided with Jupiter July 1994 when Comet Shoemaker-Levy 9 broke up into pieces and collided with JupiterComet Shoemaker-Levy 9JupiterComet Shoemaker-Levy 9Jupiter

12. video http://www.youtube.com/watch?v=iHe klbuyBSs http://www.youtube.com/watch?v=iHe klbuyBSs