Which of the following is not an outer planet?

The outer planets are the large gas or ice giants that orbit the Sun beyond the asteroid belt. These include Jupiter, Saturn, Uranus, and Neptune. The inner planets are rocky and lie between the Sun and the asteroid belt, including Mercury, Venus, Earth, and Mars.

To determine which planet is not an outer planet, consider the location of each planet relative to the asteroid belt. Planets inside the asteroid belt are classified as inner planets and are typically smaller and rocky. Planets outside the asteroid belt are outer planets and are generally larger and composed of gases or ices.

• Outer planets (beyond the asteroid belt): Jupiter, Saturn, Uranus, Neptune.

• Inner planets (inside the asteroid belt, rocky/terrestrial): Mercury, Venus, Earth, Mars.

• Key difference: Inner planets are rocky and smaller; outer planets are larger and primarily composed of gases or ices.