The inner solar system consists of Mercury, Venus, Earth, and Mars, which are terrestrial planets composed primarily of iron and rock. Earth has one moon while Mars has two small moons. Exploration of the inner solar system has involved numerous spacecraft orbiting and exploring each planet, such as Curiosity and Opportunity rovers on Mars, decades of missions to Venus, and fly-bys and long-term missions to Mercury.

1. THE INNER
SOLAR SYSTEM
FACTS ABOUT

2. THE INNER
SOLAR SYSTEM▸ Mercury, Venus, Earth, and Mars
▸ Made up of mostly iron and rock
▸ Known as terrestrial (or earth-like) planets because of their similar size
and composition
‣ Earth has one moon
‣ Mars has two moons, Deimos and Phobos

3. EXPLORATION OF THE INNER SOLAR
SYSTEM
▸ Earth surrounded by spacecraft
▸ Mars explored by Curiosity, Opportunity, and Spirit rovers; Mars
Reconnaissance Orbiter, and Viking landers and rovers
▸ Venus explored by American, European, and Soviet spacecraft for
decades
▸ Mercury explored by several fly-bys and two long-term missions:
Messenger (concluded) and BepiColombo (to launch in 2018)

4. TEST YOURSELF
▸ How are the four planets of the inner solar system alike?
▸ List some missions that were conducted for exploration of Mars, Venus,
and Mercury