Terrestrial Planets

rocky worlds · inner planets · solar system · geology

Made of rock and metal. Terrestrial planets are built from solid materials like stone and metals, not gas like some other planets. Earth, Mercury, Venus, and Mars are all terrestrial planets in our Solar System.

Closest to the Sun. The terrestrial planets live in the inner part of our Solar System, orbiting nearest to the Sun. All four of them stay closer to the Sun than the giant gas planets that live farther out.

Named after Earth. The word terrestrial comes from Latin words meaning Earth, because these planets have an Earth-like structure with solid rocky surfaces. Even though Mars and Venus are very different from Earth, they share the same rocky, solid nature.

Studied by many scientists. Geologists, astronomers, and geophysicists all study terrestrial planets to understand how rocky worlds work. Learning about Mercury, Venus, and Mars helps scientists understand Earth better.

Moons count too. Some scientists count certain moons as terrestrial planets because they're made of rock and metal just like the planets. Earth's Moon and Jupiter's moon Io could be considered terrestrial by this definition.