Why do outer planets have rings but the inner planets don't?

There is no definitive answer to this question, but theories suggest that rings are created when a moon approaches a planet too closely and is then collapsed onto the planet by the planet's gravity. Since the outer planets have many moons, this theory may be accurate but it is not conclusive.

Outer planets have rings because they have a greater abundance of ice and rocky debris in their outer regions, which can coalesce to form rings under the influence of their strong gravitational fields. In contrast, inner planets like Earth, Mars, Venus, and Mercury do not have rings because they lack the necessary conditions for ring formation, such as sufficient quantities of ice and debris, and their gravitational fields are not strong enough to maintain stable ring structures. Additionally, the proximity of inner planets to the Sun increases the likelihood of gravitational disruptions from solar tides, preventing the formation and stability of rings around these planets.