Which planet's orbit marks the outer limit of the asteroid belt?

Which planet's orbit marks the outer limit of the asteroid belt?

• A. Earth
• B. Neptune
• C. Jupiter
• D. Saturn

Answer: (C)

The outer edge of the asteroid belt is set by the gravitational influence of a giant planet. Jupiter’s strong gravity dominates the region where the belt lies, and its resonances destabilize or eject material beyond its orbit. As a result, long-lived, stable asteroid orbits don’t extend past roughly Jupiter’s orbital distance, so that orbit marks the belt’s outer limit. Inside the belt, other bodies like Mars define the inner edge, but the key idea here is that Jupiter defines the outer boundary. Earth sits inside the belt’s region, while Neptune and Saturn are farther out and do not determine the belt’s outer edge.

The outer edge of the asteroid belt is set by the gravitational influence of a giant planet. Jupiter’s strong gravity dominates the region where the belt lies, and its resonances destabilize or eject material beyond its orbit. As a result, long-lived, stable asteroid orbits don’t extend past roughly Jupiter’s orbital distance, so that orbit marks the belt’s outer limit. Inside the belt, other bodies like Mars define the inner edge, but the key idea here is that Jupiter defines the outer boundary. Earth sits inside the belt’s region, while Neptune and Saturn are farther out and do not determine the belt’s outer edge.