Earth’s Solar System

The Earth's solar system includes the Sun and all the objects that orbit it. These include the Earth, its Moon, the other planets and their moons, dwarf planets, asteroids and comets.

The planets of the Solar System, in order of their distance from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

For a long time, Pluto was thought to be a planet. However, it is now considered a dwarf planet, along with at least four other bodies - Ceres, Eris, Haumea and Makemake.

Mercury, Venus, Earth and Mars, the four innermost planets, are called terrestrial planets because they are similar to the Earth, consisting mostly of metal and rock.

Jupiter, Saturn, Uranus and Neptune, the outermost planets, are known as gas giants, because they are made up mostly of hydrogen and helium and are much more massive than the terrestrial planets.

Mercury and Venus have no moons (satellites). Our earth has one and Mars has two.

Jupiter has 63 known moons. Saturn has at least 60 moons. Uranus has at least 27 moons and Neptune, 15.

There is a large asteroid belt between Mars and Jupiter.

The dwarf planet Ceres lies within the asteroid belt.

Trans-Neptunian Region

The area of the Solar System that lies beyond Neptune is known as the Trans-Neptunian Region. Most Trans-Neptunian objects are relatively small and made up of ice and rock.

Kuiper Belt

The Kuiper Belt, named after the Dutch-American astronomer Gerard Kuiper, extends beyond the orbit of Neptune.

It is about 55 Astronomical Units (AU - the distance from the Earth to the Sun) from the Sun.

Objects in the Kuiper Belt are composed mostly of frozen volatiles, substances that would be liquid or gas on Earth, such as water, ammonia and methane.

There are over a thousand known Kuiper Belt objects.

The dwarf planets Pluto, Eris, Makemake and Haumea lie in the Kuiper Belt.

Oort Cloud

Astronomers believe that there is a spherical cloud of icy objects between one and two light years from the Sun. They call this cloud the Oort Cloud, after Dutch astronomer Jan Hendrik Oort.

Some comets are believed to originate in the Oort Cloud.