3. Water Comets are partly made of ice When comets go near the sun, some of the ice melts and the comet gets smaller This is how most comets die, they get smaller and smaller Tools for Discovery and Investigation Spaceguard is a program that tracks any big objects in space like comets, asteroids or meteors that could hit us The Hubble telescope was launched by NASA and takes pictures in space It was originally inaccurate, but they sent people into space to fix it Satellites and traveling probes can also help us discover things about the solar system
4. Scale Comets are about 5-10 kilometers wide Comet tails are usually 100,000 kilometers The larger the comet, the larger the tail Two recent Oort Cloud comets were Hyakutake and Hale-Bopp Hyakutake was average in size and came 15 million kilometers close to earth Hale-Bopp was unusually big, but it didn’t aproach closer than 1.32 AU* to earth Bright comets can be seen every 5-10 years *Note: 1 astronomical unit is 149,598,000 kilometers
5. Comet Tails Dust tails shed comet materials from the nucleus Ion tails are made of ions, electrically charged atoms, and always face away from the sun The solar wind helps cause the ion tails Solar radiation ionizes the material in comets Comets only have tails when they are near the sun Ion tails always face away from the sun Black=nucleus Tan=coma Yellowish=head of comet Blue=dust tail Red=ion tail Head of comet
7. States of Matter, Materials and Densities The Oort Cloud has a dense core 1/6 of the icy objects in the Oort cloud are in the dense core A giant molecular is a cloud that is far more massive than the sun. It is the birthplace of stars and solar systems. When encountered it can redistribute comets in The Oort Cloud Tools For Discovery and Investigation The Oort cloud is named after Jan H. Oort
8. Gravity, Orbiting and Centripetal Forces Stars in The Milky Way affect The Oort Cloud’s gravity The Oort Cloud can sometimes be the source of long period comets Sometimes long period comets in The Oort Cloud are pulled by planets gravity and turned into short period comets Scale The total mass of all the comets in The Oort Cloud is 40 times that of earth* *Note: Earth is 5.7 times 10 to the 24th power The Oort cloud is 3 light years long and 3 light years away from the sun Comets are usually tens of millions of kilometers apart within The Oort Cloud
9. Bibliography Rosanna, H. (2011, February 3). The oort cloud. Retrieved from http://www.solarviews.com/eng/oort.htm Rosanna, H. (2011, February 3). Comet introduction. Retrieved from http://www.solarviews.com/eng/oort.htm Davies, J. (2001). Beyond pluto. Cambridge, United Kingdom: Cambridge University Press. University of Washington. "Crashing Comets Not Likely The Cause Of Earth's Mass Extinctions." ScienceDaily 31 July 2009. 3 February 2011 <http://www.sciencedaily.com /releases/2009/07/090730141552.htm>. Harvey, S. (2011, February 4). Deep impact. Retrieved from http://solarsystem.nasa.gov/deepimpact/index.cfm
