Solar system

Solar System

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, such as the five dwarf planets and small Solar System bodies.

Structure and Composition

The Solar System is composed of a variety of celestial bodies including the Sun, planets, dwarf planets, asteroids, comets, and meteoroids. The primary component, the Sun, accounts for more than 99.86% of the total mass of the Solar System.

Sun

The Sun is the Solar System's star and by far its most massive component. Its large mass (332,900 Earth masses) produces temperatures and densities in its core high enough to sustain nuclear fusion, which releases enormous amounts of energy, mostly radiated into space as electromagnetic radiation, peaking in visible light.

Planets

The Solar System includes eight planets that orbit the Sun in distinct paths. In order of distance from the Sun, they are the four terrestrial planets: Mercury, Venus, Earth, and Mars; and the four giant planets: Jupiter, Saturn, Uranus, and Neptune.

Dwarf Planets

There are five known dwarf planets in the Solar System. The most famous is Pluto, which was considered the ninth planet until its reclassification in 2006. The other four are Eris, Haumea, Makemake, and Ceres.

Small Solar System Bodies

The small Solar System bodies include asteroids, comets, meteoroids, and other celestial objects in orbit around the Sun. The asteroid belt, located between Mars and Jupiter, contains the majority of known asteroids.

Exploration

The exploration of the Solar System has been conducted primarily by robotic spacecraft, although the Moon has been visited by humans. There are also ongoing studies to explore the possibility of colonizing other planets, primarily Mars.

See Also

• Formation and evolution of the Solar System
• Planetary system
• Interplanetary medium
• Astronomy