“Gauging the Solar System” is a set of projects to measure astronomical values, mainly solar system parameters, for yourself.  I strongly believe that making measurements for yourself is a great way of developing an understanding of the geometry and dynamics of the solar system.  It also turns out to be a lot of fun.  I have been doing this sort of astronomy for over thirty years and many of my results are described in my book, also called “Gauging the Solar System”.  This webpage is intended to be a continuation of the book, giving new, perhaps more precise, values that I have measured recently.  It also has copies of some of the spreadsheets that I have used.   Have fun!

My book is available at


E. Roger Cowley