Transcript Eccentricity - WordPress.com

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
Sun
D
C
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
Lets try a problem!!!!
Distance between foci: 1
Length of major axis: 8
1/8= .125 MORE CIRCULAR!!!
Distance between foci: 4
Length of major axis: 12
4/12= .333….MORE ELLIPTICAL!!!
When furthest
from Sun
When closest
to Sun
FOCI DISTANCE= 60 mm
Major Axis= 90 mm
D
STAR
A
C
B
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?
LETS PRACTICE!!!!!
Explain the difference between
the geo- and helio-centric
models of the solar system.
Earthcentered
Suncentered