Astronomy Practice Exam 2025 – Complete Preparation Guide

Saturn's rings are primarily composed of rocks and ice, making this the correct choice. The rings are made up of countless small particles that range in size from tiny grains to larger chunks. These particles are predominantly composed of water ice, which can reflect sunlight brilliantly, giving the rings their bright appearance. In addition to ice, there are also various rocky materials present, including silicate compounds and other ice-rock mixtures.

The composition of Saturn's rings can vary, with some sections being largely icy while others contain more rocky material. This diverse composition is a result of various processes, such as the breakup of icy moons or comets that ventured too close to Saturn's powerful gravitational field.

The other options do not accurately describe the primary components of Saturn's rings. Gas and dust would imply a more diffuse structure rather than the distinct rings observed. Ice and water vapor does not account for the solids present in the rings, and while metals and organic compounds may be found in trace amounts, they are not the main constituents. Thus, the characterization of the rings as being primarily composed of rocks and ice is well-supported by scientific observations and data.