deletions | additions       diff --git a/The Moon.tex b/The Moon.tex  index c7e58a4..b93ce5a 100644  --- a/The Moon.tex  +++ b/The Moon.tex 
...
The Moon orbits the Earth approximately ever 28 days, so $P_m = 28 \times 24 \times 60 \times 60 = 2.4\times10^6$~seconds. I have a hard time remembering the exact form of Newton's version of Kepler's third law. No worries, though. The Moon is held in an approximately circular orbit by the force of its gravitational attraction to the Earth.   \begin{equation}  F_{\rm grav} = \frac{G M_\oplus M_{\rm moon}}{a_m^2} = M_{\rm moon}\dot{V_m}  \end{equation}  \item {\it What is the Moon's radius?}