Kepler’s Laws of Gravitation – Law 3
So how was all that math? You now understand the math of an ellipse and the math needed to explain the motion of a planet along an elliptical orbit.
How about a mathematical formula to describe the actual motion of a planet around a star? That’s all that is left…right?
Well, almost.
The mathematical proof behind Kepler’s Third Law of Gravitation in beyond that of yourself (an 11th or 12th grade student), but the findings are simple enough to work with.
Kepler found mathematically that there was a proportionality between the distance a planet is from a star and the period of the orbit.
This is to say, that the square of the period (in years) is proportional to the distance (the semi-major axis) of the planet from the star (in Astronomical Units).
You now have the skills necessary to think in terms of Keplerian Motion – reference Carl Sagan’s video below to refresh your memory visually of the three laws governing planetary motion:
This attached link is a Excel file of observations made of an exo-solar planet. What do you notice about the path the planet is taking around the parent star? Use your understanding of Kepler’s Laws to describe the statistics!
http://www.u.arizona.edu/~duboisr/Keplerian%20Motion%20Observations.xls
January 26, 2009 at 2:01 am
After looking through your blog I feel slightly ripped off by my k-12 math teachers that I never learned math in such a fascinating away and somewhat embarassed that I have never contemplated why the planets move. Not an avid blogger, I wished I had read the beginning to the end, because starting at the top and reading down was quite intimidating. Will you be posting any experiences at local astronomy events or attractions? Also how did you embed the Youtube clip within the blog?