The asteroid belt separates the jovian from the terrestrial planets. The asteroid belt is nothing more than a planet that never formed. When our solar system was created, it was created in a spiral (hence elliptical orbits) and all that extra mass that our sun did not "use" formed our planets. The asteroid belt essentially is a planet, but there was never any center mass to hold it all together. The idea of the reef and the awoken playing a big part makes sense because of course the reef is in the asteroid belt.