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Q&A: Dark Matter
                        
                        
                    
            Q:
Regarding the Dark Matter Mystery. Did the equation for the mass
               of the galaxy include planetary zones for the stars? Just
               looking at our own solar system, a large proportion of the mass
               seems to be in the planetary zone and made up of elements with
               much greater mass than just hydrogen. Also these planets and
               debris fields probably wouldn't emit much in the way of radio
               energy and if planets existed in sufficient numbers would
               increase the mass of the galaxy by quite a lot.
                
               A:
The mass of all the planets in our solar system is about 0.1
               percent of mass of the Sun, so if our solar system is typical,
               the total mass of planets in the galaxy is small compared to
               that of stars.
               
                               
               
               
   
        

