Which statement describes the distinction between inner and outer planets?

Which statement describes the distinction between inner and outer planets?

• A. Inner planets are rocky and smaller; outer planets are gaseous and larger
• B. Inner planets are gaseous; outer are rocky
• C. All planets are similar in composition
• D. Outer planets are closer to the Sun than inner planets

Answer: (A)

The distinction being tested is how planetary composition and size differ with distance from the Sun. The inner planets—Mercury, Venus, Earth, and Mars—are rocky and solid, relatively small, and dense. Beyond them, the outer planets—Jupiter, Saturn, Uranus, and Neptune—are much larger and are composed mostly of gases (and ices) with thick atmospheres, rather than solid surfaces. This divide reflects how the early solar system cooled: rocky material condensed close to the Sun, while icy materials and light gases could condense farther out, allowing giant planets to form there. So the statement that inner planets are rocky and smaller while outer planets are gaseous and larger accurately describes the distinction.

The distinction being tested is how planetary composition and size differ with distance from the Sun. The inner planets—Mercury, Venus, Earth, and Mars—are rocky and solid, relatively small, and dense. Beyond them, the outer planets—Jupiter, Saturn, Uranus, and Neptune—are much larger and are composed mostly of gases (and ices) with thick atmospheres, rather than solid surfaces. This divide reflects how the early solar system cooled: rocky material condensed close to the Sun, while icy materials and light gases could condense farther out, allowing giant planets to form there. So the statement that inner planets are rocky and smaller while outer planets are gaseous and larger accurately describes the distinction.