Outer planets

The planets of the solar system are divided into inner planets and outer planets.

The classification defines two groups that are very different in their chemical structure. All inner planets are terrestrial planets and therefore differ materially from the outer planets, which are all gas giants. The inner planets orbit the sun in the asteroid belt, the outer outside.

The inner planets are:

• Mercury
• Venus
• Earth
• Mars

The outer planets are:

• Jupiter
• Saturn
• Uranus
• Neptune

Until 24 August 2006, Pluto was one of the outer planets. According to a new definition of planet by the International Astronomical Union ( IAU) to him but this status has been revoked. A well-known mnemonic for the order of the planets from the sun Sonnennah by remote reads: " My father explained to me every Saturday our night sky. ", The first letter shall coordinate consistent with those of the planets.

Lower and upper planets

Opposite this planetologisch reasoned distinction, the division into lower and upper planets refers to as category pair of observational astronomy from Earth to their different observation conditions, due to their orbit within or outside the Earth's orbit.