Terrestrial Planets
Compact, rocky worlds with solid silicate crusts and metallic cores. They have few or no moons and no ring systems.
Members: Mercury, Venus, Earth, Mars
Planetary Categories
Planets are primarily classified by their bulk composition and location relative to the asteroid belt.
Gas Giants
Massive worlds composed predominantly of hydrogen and helium, lacking a solid surface and surrounded by extensive moon and ring systems.
Members: Jupiter, Saturn
Ice Giants
Smaller than gas giants and enriched with heavier volatile "ices"—water, ammonia, and methane—above a rocky core.
Members: Uranus, Neptune
Dwarf Planets
Spherical bodies that orbit the Sun and have enough mass for self-gravity, but have not cleared their orbital neighborhood of other debris.
Notable Examples: Ceres, Pluto, Eris
Planetary Moons
Natural satellites orbiting planets and dwarf planets rather than the Sun directly—ranging from captured asteroids to ocean-bearing icy worlds.
Notable Examples: Moon, Europa, Ganymede, Titan, Triton
Interactive World Explorer
Filter by classification and select any planet, dwarf planet, or major moon to inspect its profile.
The IAU Planet Definition (2006)
To be classified as a full planet in the Solar System, a celestial body must satisfy all three International Astronomical Union criteria. Meeting only the first two makes it a dwarf planet.
- Orbits the Sun: It must be in direct orbit around the Sun (not a moon orbiting another planet).
- Hydrostatic Equilibrium: It has sufficient mass for its self-gravity to pull it into a nearly round shape.
- Cleared Neighborhood: It is gravitationally dominant in its orbital zone, having cleared away comparable objects.
Quick Comparison Table
Key physical and orbital metrics across all eight planets, dwarf planets, and major moons.
| World | Classification | Location / Host | Diameter (km) | Orbital Period | Known Moons |
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