What is Gas giant: Definition and 15 Discussions

A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are sometimes known as failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. 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"). For this reason, Uranus and Neptune are now often classified in the separate category of ice giants.Jupiter and Saturn consist mostly of hydrogen and helium, with heavier elements making up between 3 and 13 percent of the mass. They are thought to consist of an outer layer of molecular hydrogen surrounding a layer of liquid metallic hydrogen, with probably a molten rocky core. The outermost portion of their hydrogen atmosphere is characterized by many layers of visible clouds that are mostly composed of water and ammonia. The layer of metallic hydrogen makes up the bulk of each planet, and is referred to as "metallic" because the very large pressure turns hydrogen into an electrical conductor. The gas giants' cores are thought to consist of heavier elements at such high temperatures (20,000 K) and pressures that their properties are poorly understood.The defining differences between a very low-mass brown dwarf (which can have a mass as low as roughly 13 times that of Jupiter) and a gas giant are debated. One school of thought is based on formation; the other, on the physics of the interior. Part of the debate concerns whether "brown dwarfs" must, by definition, have experienced nuclear fusion at some point in their history.

View More On Wikipedia.org
  1. Skyland

    Could an Interstellar Gas Planet Heat its Moon Without Fusion Ignition?

    Summary: Can an interstellar planet be hot enough to heat it's terrestrial moon without igniting fusion? I am a science fiction writer, however I am studying astrophysics to better captivate audiences with real and believable plots, The idea in question is an interstellar sub brown dwarf gas...
  2. Chatterton

    Living on the far side of a tide-locked moon

    You're the Galileo for a developing society on a remote archipelago on the far side of a tide-locked moon orbiting a gas giant. How do you figure out your place in that solar system? How do you convince others, who believe your world to be the center of the universe, of the truth? Will a road...
  3. Tris Fray Potter

    B Why is planet X always depicted as being blue?

    I know that it is probably a gas giant, but why blue? Saturn and Jupiter, and even Uranus aren't blue, so why would Planet X be blue?
  4. T

    Could an Exomoon Survive Permenant Shade from a Gas Giant?

    Hello, thank you for reading my post. For a story I am working on I am wondering about the plausibility of some star and planet configurations. I have done some web research on my own and learned a lot, but for some things I think my vocabulary and knowledge is too limited to search for exactly...
  5. L

    What is the Density Change Towards the Centre of a Gas Giant?

    I'm currently completing a project about gas giants. Could anyone point me in the right direction to find out about the density change as one approaches the centre of a giant? I can kind of do it if I assume it's incompressible, but does anyone know the current theories for it in practice...
  6. K

    Understanding orbital characteristics of a moon of a gas giant

    Hi, I am doing research for a story and would like to set it on a habitable moon in orbit around a gas giant. I've done a bit of research on this and understand that the moon would likely be tidally locked, so that only one face of the Moon would ever face the gas giant. I understand that...
  7. N

    Planetary gas giant atmospheres

    Hi guys, I've had a question nagging at me for a while - When I was at school, my chemistry teacher taught us that the outer electrons of atoms were bound to the attraction of the nucleus, and the more layers of electrons that were added, the weaker the attraction due to electron "shielding"...
  8. Simfish

    Do moons always get more attention than the gas giant planets they orbit?

    It certainly seems like it. People are far more excited about Titan than they are about Saturn. And the same is true for several other Saturnian moons. Same with Jupiter and its 4 biggest moons. People seem to care more about its 4 moons than Jupiter itself. I'm no exception. But certainly, I...
  9. rrw4rusty

    What gas giant, what moon(s) are split in half and.

    Hello, I searched and searched, even emailed my astronomer friend in the land down under but I need the answer NOW! LOL. One of our gas giants has a moon that is split in half and when the two halfs meet they trade places. Which gas giant? What are the names of the two half moons...
  10. V

    What is the composition of a gas giant's atmosphere?

    I have a silly question: what do people understand by "the atmosphere of a gas giant" ? Isn't most of the planet "all atmosphere", or how should one picture this ?
  11. Z

    Might A Hot Jupiter Require Another Gas Giant - 3-body Problem?

    How might hot jupiters arrrive close in, since gas sufficient for their formation would be seem to be further outward? It might seem to require a 3-body 'solution'. That is, must another gas giant have been in the mix for much earlier stages? Perhaps ejecting 1 giant, and retaining the other in...
  12. N

    Exploring the Limits of Gas Giant and Terrestrial Worlds

    Dear all, Is anyone aware of any physicists who have worked/working on the theoretical limit to how small a gas giant can form? What is the minimum radius and mass that a gas giant can form at before it's simply evaporates too quickly to become a stable world? I'm guessing some fluid...
  13. H

    Gravity & Our Gas Giant Planets

    Why doesn't the immense gravity of Jupiter and the others turn the gases into solids? (More than just a tiny core, that is.) Does the "gas" at the surface act like a hard solid? About 10 years ago that comet, Shoemaker-Levy 9, entered Jupiter's atmosphere, broke up, and caused explosions on the...
  14. Nim

    The Closest Gas Giant: Why is Jupiter so Big?

    How I understand it, the four inner planets are rocky planets because the Sun boiled off most of their atmospheres, while the planets past Mars retained theres. I was wondering if the reason why Jupiter is so big is because it is the closest planet to Mars, so it caught most of the atmosphere...
  15. T

    Nuclear ignition of gas giant atmospheres

    Out of curiosity, can you produce a self perpetuating nuclear fusion chain reaction - in effect a new sun - by dropping a nuclear bomb deep into the atmosphere of a hydrogen rich gas giant? If a powerful enough weapon was fired on a non-hydrogen atmosphere like Earth's, bearing in mind that...