The Solar System
An overview of the solar system and its planets, moons and smaller bodies.
Contents
The Solar System consists of the Sun and everything bound to it by gravity. It formed about 4.6 billion years ago from a collapsing cloud of gas and dust, and it orbits within one of the galaxies we can observe, the Milky Way.
The planets
The four inner planets, Mercury, Venus, Earth and Mars, are small and rocky. The outer planets are far larger: Jupiter and Saturn are gas giants, while Uranus and Neptune are ice giants.
Smaller bodies
The asteroid belt lies between Mars and Jupiter. Beyond Neptune, the Kuiper belt holds icy objects, including the dwarf planet Pluto.
Exploration
Spacecraft have visited every planet. Voyager 1, launched in 1977, is the most distant human-made object.
Moons
More than two hundred moons orbit the planets, and Saturn has the most known moons of all.