They aren't in the middle of the “planetary lineup”. The four inner planets are all terrestrial. The four outer planets are gas (the last fwl sometimes disting

They aren't in the middle of the “planetary lineup”. The four inner planets are all terrestrial. The four outer planets are gas (the last fwl sometimes distinguished instead as “ice”) giants. There are dwarf planets (a separate category from, rather than sibcategory of, planets) closer and farther, but no known rocky planets beyond the gas/ice giants.