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Outer, gaseous or jovian planets

The outer planets (or gaseous or giant or Jovian) are located beyond the asteroid belt.

The internal structure of the outer planets is:

  • small solid core.
  • thick, fizzy wrapper. Master the hydrogen. In addition, it contains He, C, N, Si, Mg, S.

The main characteristics of the outer planets are:

  • They have a fast turnover period. They take about 10 hours to turn on themselves.
  • They are gaseous. They do not have a solid surface.
  • Their density is low because they are formed mainly by hydrogen and helium, but due to their low mass and size, nuclear fusion reactions do not take place.
  • They have many satellites orbiting around them.
  • They have ring systems around them.

The outer planets are:


Jupiter is the largest planet of the Solar System. Its mass corresponds to almost 75% of the mass of all the planets in the Solar System. For example, its mass is 318 times the mass of Earth,  almost two and a half times that of the other planets combined (with a mass 318 times that of Earth and three times that of Saturn , plus be, in terms of volume, 1317 times larger than the Earth).

Jupiter is a gaseous planet, made up mainly of hydrogen and helium, without a defined interior surface. Its core is composed of frozen gases from which gases (hydrogen and some helium) come out that form a dense atmosphere. The movement of the clouds in this atmosphere generates a band that covers its surface.

Like the rest of the outer or gaseous planets, Jupiter has rings although they are much less bright than those of Saturn. They are rocky fragments, which makes these rings very dark and cannot be seen from Earth.

Jupiter currently known him to 79 satellites, although four of them, discovered by Galileo Galilei in 1610, are the most important:

  • Io:  It is the closest satellite to Jupiter. The great gravitational attraction that Jupiter exerts causes tides that cause a very active volcanism.
  • Europa: It is covered by ice, and an ocean of liquid water is believed to exist under a crust of ice.
  • Ganymede: It is the largest satellite in the entire Solar System.
  • Calixto: It is the furthest satellite from Jupiter.
By NASA/JPL/University of Arizona ( [Public domain], via Wikimedia Commons


Saturn is the second largest planet in the Solar System, after Jupiter. The most striking thing about Saturn are its bright rings, made up of fragments of ice and frozen gases (not rocky fragments like Jupiter). It is the only ring system that can be seen from Earth.

Saturn has 62 satellites, some known since before the beginning of space research, such as Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus and Phoebe. The largest satellite is Titan, and it is the only satellite in the Solar System with a significant atmosphere.


Uranus and Neptune are the most distant gaseous planets, and they are also giant planets compared to terrestrial planets, although they are much smaller than Jupiter and Saturn.

Although the atmosphere of Uranus is similar to that of Jupiter and Saturn because it is made up of hydrogen and helium, its methane content stands out , which gives it its blue-green color.

Uranus also has rings but very dark.

It currently has 27 known satellites, among which Miranda, Ariel, Umbriel, Titania and Oberón stand out.

The axis of rotation of Uranus is inclined 97.77º with respect to the plane of the ecliptic, almost to its plane of revolution around the Sun. That is, the north pole and the south pole meet where the equator of the other planets is.


Neptune is quite similar to Uranus, with different compositions than Jupiter and Saturn.

Neptune has a composition quite similar to that of the planet Uranus, and both have compositions that differ greatly from the other gas giants, Jupiter and Saturn. In its atmosphere, like Uranus, it also has methane that gives it a blue color.

Neptune also has a ring system made up of ice and silicates, which give it a dark color.

14 satellites of Neptune are known, among which Proteus, Triton and Nereid stand out.