Overview Of The Solar System

Broadly speaking, the Solar System can be divided into two zones. Bodies in the inner zone are composed of rock and metal, while those in the outer zone consist largely of gas and ice. A somewhat more detailed picture of the Solar System includes:

Some basic properties of planets and other objects are listed below:

Planet Semimajor Period Diameter Mass Composition Atmosphere
axis (AU) (year) (km) (M)
Mercury 0.39 0.24 4878 0.055 metal, rock
Venus 0.72 0.62 12102 0.814 rock, metal CO2, SO2
Earth 1.00 1.00 12756 1.000 rock, metal N2, O2, H2O
Moon 3476 0.012 rock
Mars 1.52 1.88 6787 0.107 rock, metal CO2, N2, Ar
asteroids 2 to 3.5 3 to 6 <1000 small rock, metal
Jupiter 5.20 11.86 142800 317.5 gas (H, He) H2, He, CH4, NH3
Ganymede 5262 0.025 ice, rock
Saturn 9.54 29.46 120660 95.1 gas (H, He) H2, He, CH4, NH3
Titan 5150 0.023 ice, rock N2, Ar, CH4
Uranus 19.18 84.07 50800 14.5 gas, rock H2, He, CH4
Neptune 30.06 164.8 50500 17.2 gas, rock H2, He, CH4
Pluto 39.44 248.6 2300 0.0016 rock, ice?
KBOs 35 to 200 to <100 tiny ice, dust

Inner Solar System. In order of increasing distance from the Sun, the orbits of Mercury, Venus, Earth, and Mars, surrounded by the asteroid belt.

Outer Solar System. Left: orbits of Jupiter, Saturn, Uranus, Neptune, Pluto, and a typical comet, surrounded by the Kuiper belt. Right: the Oort cloud, an extended, roughly spherical swarm of KBOs.

Joshua E. Barnes (barnes@ifa.hawaii.edu)

Last modified: August 15, 2001