Planetary Classification and Mercury
The solar system's planets are divided into two main categories: inner and outer planets, separated by the asteroid belt. Temperature and features of Mercury planet make it unique as the smallest and closest planet to the Sun.
Vocabulary: Inner planets are primarily composed of rock, while outer planets consist mainly of gases.
Highlight: Mercury experiences extreme temperature variations due to its proximity to the Sun and lacks an atmosphere.
Definition: Planets are spherical objects that orbit around the Sun under their own gravitational influence.