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Is anyone familiar with HS-ESS1-4 Motion of Orbiting Objects? This is allegedly a 9th grade level item. Use mathematical or computational representations to predict the motion of orbiting objects in the solar system. [Clarification Statement: Emphasis is on Newtonian gravitational laws governing orbital motions, which apply to human-made satellites as well as planets and moons.] [Assessment Boundary: Mathematical representations for the gravitational attraction of bodies and Kepler’s Laws of orbital motions should not deal with more than two bodies, nor involve calculus.] I'm not really sure what they are getting at. Are we doing calculations with Keplers 2 and third laws? Are we setting gravitational force (Gmm/r^2 = mv^2/r) to sovle for velocity of orbits? Both? Neither? Can you shed some light on what they really want?

I would you suggest you download the Science Object "Earth, Sun, and Moon: Our Moving Earth" from the Learning Center and look it over. I think it will answer all of your questions.

For a practical, and timely, application, the NASA Kepler mission site developed a bunch of activities: http://kepler.nasa.gov/education/activities/ I especially like the Transit tracks pdf, which can be used as a stand alone: http://kepler.nasa.gov/education/activities/transitTracks/ Although making a set of Lego Orreries and using a web camera for a light detector with the Light Grapher app they developed is really cool if you have time (from the bottom of the page): http://kepler.nasa.gov/education/ModelsandSimulations/LegoOrrery/ http://kepler.nasa.gov/files/mws/LEGOorrery2011.pdf http://kepler.nasa.gov/education/ModelsandSimulations/lightgrapher/ Note you don't need a light bulb for a light source, as web cameras (even ones built into laptops) these days are sensitive enough to work just with a white styrofoam ball for the "sun." I could post a pdf of the curves we made, perhaps even a video, if people were interested. -- Malcolm