The Planets and Space Exploration
The four inner planets
at the center of the solar system
Mercury,
Venus,
Earth,
Mars,
are known as the terrestrial planets because
they are solid, rocky bodies.
Jupiter,
Saturn,
Uranus, and
Neptune are all composed primarily of gas and are
known as the Jovian planets or Gas Giants (Uranus and Neptune are sometimes called Ice Giants).
The space beyond Neptune contains thousands of icy worldlets that are not quite large enough to be full-fledged planets. Three dwarf planets - Pluto, Haumea, and Makemake - orbit in a region called the Kuiper Belt. Another dwarf, Eris, is also found beyond Neptune but in a more elliptical orbit.
The asteroid belt, between
Mars and Jupiter, is made of thousands
of chunks of rock which orbit the Sun. The dwarf planet Ceres orbits within the asteroid belt. Comets are small icy bodies that travel past the Sun and give off gas and dust
each time they pass by.
Unmanned spacecraft
have traveled to all the full-sized planets in the solar system and
taken pictures of the planets and many of their moons. They have also
taken measurements that tell us about the particle, electromagnetic, and
gravitational environment near the planets. This information can be used
to tell us about the planets interior, surface, atmosphere, and magnetosphere.
Big, Bigger, Biggest
A Solar System Model Builders Guide
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