The center of mass in an extrasolar system
-  What is the circumference of the star's orbit?
        In other words, how far does the star travel
        as it makes one complete circle? 
 
-  What is the radius Rs
        of the star's orbit around the center of mass? 
 
-  The planet is circling the star with a much larger
        orbital radius Rp, but
        with exactly the same period P.
        Use Kepler's Third Law to figure
        out the radius of the planet's orbit.
  
   
 
 
       
        You can assume that
        
        -  (Rp + Rs) is roughly (Rp)
             
 
        -  the mass of the star is about the same as the mass of the Sun
             
 
        
  
   
 
 
     
-  How does the planet's orbit compare in size of the
        orbit of the Earth around the Sun?
    
 
-  Use the ratio of orbital radii to figure out
        the ratio of masses.
        Then estimate the mass of the planet.
    
 
-  How does the planet's mass compare to the mass of the Earth?
    
 
-  Would you like to live on this planet?