Meet the eight planets
The eight planets share a star but differ greatly in structure and surroundings. Start with their order, then compare families instead of treating them as eight differently colored balls.
- Mercury · Venus
- Earth · Mars
- Jupiter · Saturn
- Uranus · Neptune
Start with the order
Moving outward from the Sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. An orbit’s position in this sequence is different from a planet’s size. The largest planet is not the farthest one.
The four rocky planets
Mercury, Venus, Earth and Mars are terrestrial planets with solid surfaces. A rocky surface does not mean identical conditions: atmospheres and surface environments differ. In the explorer, compare their descriptions as well as their appearance; an illustrative texture cannot communicate the whole environment.
The gas giants
Jupiter and Saturn form the gas-giant pair. They should not be imagined as enlarged versions of Earth with a familiar solid ground beneath a thin sky. Saturn’s prominent rings are visually useful for identification, but rings are material orbiting the planet rather than a single solid disk.
The ice giants
Uranus and Neptune are classified as ice giants, a different group from Jupiter and Saturn. The name refers to their composition and planetary classification; it is not an instruction to picture a small frozen surface. Use the category to compare their interiors rather than infer a place to stand from their color.
The Sun and Moon are not extra planets
The Sun is the star at the center of this planetary system. Earth’s Moon is a natural satellite. The explorer includes both to explain relationships, but their presence does not change the number of planets. Other moons and smaller bodies are not comprehensively represented.
Compare one property at a time
Select a rocky planet and a giant. Compare diameter first, orbital period second, and rotation third. Keeping those comparisons separate avoids confusing a large body with a long year or a slow spin. The rendered sizes are adjusted for readability, so consult the facts panel for physical measurements.