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Name: HA Sinoff
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Please tell me about the oort cloud. My student would like to do a science fair project on the subject and I am looking for reference materials to help her.

The Oort Cloud (note: singular tense) is the theoretical region associated with our solar system where most comets spend most of their time. This is possible because most comets have highly elliptical orbits. Look for a college undergraduate text book on astronomy. This may be beyond the level of a high school student, but a possible project might be to use the orbital parameters of known reappearing comets to calculate the dimensions of the Oort Cloud. It would also be interesting to learn more about Professor Oort, and how he came up with the idea.


The best write up on the Oort cloud of the astronomy texts I have is in "Exploration of the Universe" by Abell, Morrison, and Wolff. Some astrono- mers believe that in addition to the Oort cloud, there is another reservoir of comets (the source of "short-period" comets) called the Kuiper belt. I consulted the on-line Reader's Guide and found some magazine articles that, from the abstracts, look promising:

Sky and Telescope Jan. '93 p. 15, p. 26-9
Sky and Telescope Apr. '93 p. 44-5 -- about Jan Oort
Astronomy Sept.'92 p. 40-7
Discover Feb. '91 p. 8

RC Winther

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