From: fortunati.luigi@gmail.com   
      
   The traveling twin starts and travels for 4 years at speed v = 0.866c   
   and then brakes, as seen in the animation   
   https://www.geogebra.org/m/jzc4amud   
      
   Calculate the Earth-spaceship distance, before and after braking (in   
   the spaceship reference).   
      
   Calculate how many turns the Earth has made around the sun, before and   
   after braking (in the spaceship reference).   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)