Kiwanis Chico Community Observatory







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Orbital Eccentricity Project


To make the ellipse:

1.  Draw two dots near the center of your piece of cardboard.  These are the foci (plural for focus) of your ellipse.  They can be as far apart as you want, as long as your string is longer by at least an inch (believe me - it will be easier if the string has quite a bit of slack).


2.  Tape down each end of your string to a focus (dot).


3.  Gently, place your pencil or pen against the string and pull it fairly tight (you should have what looks like a triangle between the two dots).


4.  Keeping the string taut, move your pencil or pen around the two foci (dots).  Hopefully, you will now have the outline to a beautiful ellipse (if not, try again, or come out to the observatory and have a volunteer demonstrate).


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Website last updated March 16,  2006.  Hosted by Anthony Watts, KMXI Radio.  Webmasters Tiara Norris and Brendan Diamond.