Medium-sized planets are common in other systems, but there are no medium-sized planets in our solar system; instead, we have gas giants and ice giants on one hand, and small rocky planets like our Earth on the other.
Using the Nice model, scientists previously found that the gas giants Jupiter and Saturn regulate the orbits of the small inner planets (Mercury, Venus, Earth, Mars), and have prevented them from becoming unstable and falling closer to the Sun." CMI
