Do now: If a planet has a mostly oval orbit, Ms. Ware Earth Science W.O.T.D.: Eccentricity: is a measure of how an orbit Deviates from circular. A perfectly circular orbit has an eccentricity of zero; higher numbers indicate more elliptical orbits Do now: If a planet has a mostly oval orbit, Where do you think the planet would be fastest? Why? B A C Sun D
Ms. Ware Earth Science 10/7 /09 L.T.: I can understand and calculate a planet’s eccentricity. W.O.T.D.: Eccentricity: is a measure of how an orbit deviates from circular. A perfectly circular orbit has an eccentricity of zero; higher numbers indicate more elliptical orbits Do Now: Ratio Review: 1.) The Sun’s diameter is 15 miles, and the planet X’s diameter is 5 miles. A student needs to draw a small model of these objects and she decides the planet should have a 2 inch diameter. What diameter should the sun have if she wants her small drawing to remain proportional? 2.) Use the ruler on your table and draw both planet X and the sun (from above) in your notebook (*After turn and talk to the person next to you. Show them your drawing and see if they came to the same conclusion- 2minutes)
Calculate the eccentricity of the ellipse below: length of major axis 8 miles 4 miles Formula: eccentricity = distance between foci length of major axis
Distance between foci: 1 Length of major axis: 8 Lets try a problem!!!! 1/8= .125 MORE CIRCULAR!!! Distance between foci: 4 Length of major axis: 12 4/12= .333….MORE ELLIPTICAL!!!
When does a planet move slowest in its orbit? When furthest from Sun When does a planet move fastest in its orbit? When closest to Sun
FOCI DISTANCE= 60 mm Major Axis= 90 mm Questions: STAR A C Questions: 1.) What is the approximate eccentricity? 2.) As the planet moves from A to C, what happen to the gravitational attraction? 3.) At which position does planet Q have the greatest velocity? B
LETS PRACTICE!!!!!
Explain the difference between the geo- and helio-centric models of the solar system. Helio-centric Geo-centric Earth- centered Sun- centered