[Pontiac]

I guess we would in reality have to include all of the gas giants in that first line of defense.

After all Saturn, Neptune and Uranus although much smaller and less massive still sweep up their share of the debris passing through the solar system.

[jmacusa]

Any orbital body large enough to created the kind of gravity needed to capture and asteroid. Mass effects gravity. The large the mass the more gravity it exerts and that's The Big Guy, Jupiter. He's far closer to us( 818 million miles) then Neptune and Uranus are..