1. Comets By: Kaya Umeda, Cierra Yoshikawa

2. What is a Comet? Small, icy celestial body that orbits around the sun

3. Comet Parts Nucleus (ice, gas and dust) – Most of comets mass Coma (water vapor, CO2, and other gases) – Surrounds nucleus Nucleus and Coma form the head

4. Parts Cont. Ion Tail (gas) – Approaching sun, trails comet – Leaving sun, leads comet Dust tail (dust) – Long, wide tail composed of microscopic dust particles

5. Comet Path Travel in elliptical orbits Velocity increases near sun Visible near sun

6. Comet Life Cycle Departure: – Some are not bound to the sun Extinction: – Lose ice and dust each time they come near the sun. – They can lose all their ices and turn into fragile similar to asteroid

7. Comet Life Cycle Cont. Breakup: – Comets that lose all their ices break up and dissipate into clouds of dust Collisions: – Orbiting comets can collide with planets and moons

8. Characteristics Short-period comets: – Need about 200 yrs or less to complete one orbit – Originate from a disk-shaped band of icy objects

9. Characteristics cont. Long-period comets: – Takes more than 200 yrs – Comes from the nearly spherical Oort cloud even further out, which get slung inward by gravitational pull of passing stars

10. Comet Names Comet Halley- most famous comet Comet Neat Comet Kohoutek Comet Hyakutake

11. Cosmic Snowballs New theory that comets are composed of frozen water are constantly bombarding Earth Vaporize in the atmosphere, adding water vapor to environment

12. Works Cited “Comets.” All About Astronomy. N.p. 1999. Web. 11 Jan 2011. http://www.enchantedlearning.com/subjects/astronomy/comet/ “Comets.” The Nine Planets. N.p., 1994. Web. 11 Jan 2011. http://nineplanets.org/comets.html “Comets: Formation, Discovery and Exploration.” Space.com. N.d. Web. 11 Jan 2011. http://www.space.com/53-comets-formation-discovery-and-exploration.html Hamilton, J. Calvin. “Comet Introduction.” View of the Solar System. N.p. 1995. Web. 11 Jan 2011. http://www.solarviews.com/eng/comet.htm