A gas giant is a large planet composed mostly of gases, such as hydrogen and helium, with a relatively small rocky core.
All of our Solar System’s gas giants are outer planets, which means they are the furthest planets from the Sun. Compared to terrestrial planets, gas giants are extremely large and massive. For example, Jupiter has a mass 318 times the mass of Earth, which is a terrestrial planet. A gas giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the Solar System 's gas giants. The term gas giant was originally synonymous with giant planet, but in the 1990s it became known that Uranus and Neptune are really a distinct class of giant planet, being composed mainly of heavier volatile substances (which are referred to as 'ices'). A gas giant is a large planet that is not composed mostly of rock or other solid matter. Gas giants may still have a rocky or metallic core—in fact, it is expected that such a core is probably required for a gas giant to form—but the majority of its mass is in the form of gas (or gas compressed into a liquid state). In our solar system, Jupiter, Saturn, Uranus and Neptune are gas giants, also known as jovian planets. It's unclear what the dividing line is between a rocky planet and a terrestrial planet; some super-Earths may have a liquid surface, for example. Gas giants are also called Jovian planets after Jupiter, the prototype of gas giants in our Solar System. There are four gas giants in our Solar System – Jupiter, Saturn, Uranus, and Neptune. View full size image. A gas giant is a large planet composed mostly of gases, such as hydrogen and helium, with a relatively small rocky core. The gas giants of our solar system are Jupiter, Saturn, Uranus and Neptune. A gas giant describes a planet that is not composed of mostly rock and other solid substances. Gas giants are almost entirely formed of various gases. These planets are not completely gas though. At the center, is what astronomers call a rocky center. This term is somewhat misleading though because the rocky center is actually liquid compounds, including molten heavy metals.
http://www.universetoday.com/33506/gas-giants/ https://en.wikipedia.org/wiki/Gas_giant http://www.academickids.com/encyclopedia/index.php/Gas_giant http://www.space.com/17028-terrestrial-planets.html http://www.universetoday.com/33506/gas-giants/ http://www.space.com/30372-gas-giants.html http://www.universetoday.com/33506/gas-giants/
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