If you liked analyzing Pluto's orbit today, 
use some of your spare time to read all 
of section 13.4

Kepler discovered his laws by analyzing 
Brahe's careful records of the changing positions 
of Mercury, Venus, Mars, Jupiter, and Saturn 
in the sky over many years. Newton later 
"explained" Kepler's Laws by mathematically 
proving them, starting from the assumption of  
Newton's law of universal gravitation.
The book gives a modern treatment of 
Newton's proof.

I will give extra credit of 0.1 GPA points
for a correct and complete solution, 
on or before April 7, of the "applied project" 
at the end of Chapter 13. (Such a solution
must be individual work and all sources
beyond the textbook must be cited.)