How big is Jupiter for a Gas Giant?

[SergeantBlueforce]

I've always wondered how large Jupiter is in relative terms to other gas giants.

Is it a small or a large one?

[Nibb31]

It's the biggest one in our solar system.

[SergeantBlueforce]

It's the biggest one in our solar system.

Well of course I know that!

What I meant is how big is it compared to other gas giants in general.

[vger]

Pay attention, everyone. Jupiter has been drinking all night and wants to compare sizes.

[Thesonicgalaxy]

Pay attention, everyone. Jupiter has been drinking all night and wants to compare sizes.

I mean, going on a quick look here doesn't even say much as I don't think we know enough planets in the first place to say.

[Elthy]

Jupiter is close to being the largest possible gas giant (by size, not mass). If you add more gas the additional gravity would compress it more, so jupiter would get smaller.

[78stonewobble]

Jupiter is close to being the largest possible gas giant (by size, not mass). If you add more gas the additional gravity would compress it more, so jupiter would get smaller.

This...

But if I remember correctly there are also "puffy" gas giants. Ie. gas giants too close to the star that gets very hot and the atmospheres expand accordingly. So they're "bigger", but less dense.

[Armchair Rocket Scientist]

All right:

The heaviest a gas giant can get is around 13 times the mass of Jupiter. At this mass, it begins to fuse Deuterium and is considered a brown dwarf. Brown dwarfs quickly exhaust their supply of deuterium and cool down, but the minimum mass at which deuterium could be burned is typically used as the cut off.

How small can a gas giant get? Well, it's hard to say. Uranus is only 14 Earth masses, or less than 5% the mass of Jupiter, but it is considered an Ice giant, not a gas giant. By the way, this means means most of its mass is water, ammonia, methane, etc - the hydrogen and helium envelope is a lot more massive than Earth's hydrosphere or Venus's atmosphere, but is still a minor component of the planet. However, extrasolar planets have been found. For example, three of Kepler-11's planets are "super-earths" with densities less than that of water. In fact, their densities are comparable to that of Saturn, but with far less gravitational compression, and although they're hot they're still much cooler than most "puffy" gas giants. However, such planets might be considered "gas dwarfs." Typically the cutoff is set at around 10 Earth masses.

If I take the logarithmic mean of the upper and lower bounds for gas giant masses (logarithmic mean = (4000-10)/ln(4000/10), I get an answer of about 2 Jupiters. In reality though, smaller planets are going to be more common than larger ones. I can't find good information on this at the moment, but I think some planet formation models predict a "sub-saturn desert" with planets of around 30-40 Earth masses being rare. Uranus-neptune mass is supposed to be most common for giant planets, but most of those would probably be ice giants.

With all this in mind, I'd say that the "average" gas giant would probably be somewhere between Saturn and Neptune in mass, with Jupiter being a bit above average, but far from the largest.

Really, it's a bit like the sun: larger than 90% of stars, but there are far larger examples.

[lajoswinkler]

All right:

The heaviest a gas giant can get is around 13 times the mass of Jupiter. At this mass, it begins to fuse Deuterium and is considered a brown dwarf. Brown dwarfs quickly exhaust their supply of deuterium and cool down, but the minimum mass at which deuterium could be burned is typically used as the cut off.

How small can a gas giant get? Well, it's hard to say. Uranus is only 14 Earth masses, or less than 5% the mass of Jupiter, but it is considered an Ice giant, not a gas giant. By the way, this means means most of its mass is water, ammonia, methane, etc - the hydrogen and helium envelope is a lot more massive than Earth's hydrosphere or Venus's atmosphere, but is still a minor component of the planet. However, extrasolar planets have been found. For example, three of Kepler-11's planets are "super-earths" with densities less than that of water. In fact, their densities are comparable to that of Saturn, but with far less gravitational compression, and although they're hot they're still much cooler than most "puffy" gas giants. However, such planets might be considered "gas dwarfs." Typically the cutoff is set at around 10 Earth masses.

If I take the logarithmic mean of the upper and lower bounds for gas giant masses (logarithmic mean = (4000-10)/ln(4000/10), I get an answer of about 2 Jupiters. In reality though, smaller planets are going to be more common than larger ones. I can't find good information on this at the moment, but I think some planet formation models predict a "sub-saturn desert" with planets of around 30-40 Earth masses being rare. Uranus-neptune mass is supposed to be most common for giant planets, but most of those would probably be ice giants.

With all this in mind, I'd say that the "average" gas giant would probably be somewhere between Saturn and Neptune in mass, with Jupiter being a bit above average, but far from the largest.

Really, it's a bit like the sun: larger than 90% of stars, but there are far larger examples.

No, Uranus and Neptune aren't called ice giants for those reasons. They got the name because their ice content is significantly higher than of Jupiter and Saturn. Most of their mass is hydrogen and helium, "permanent gases".

Ice giants are a subspecies of gas giants, not something equal on the hierachy.

To comment the OP's question, if we exclude puffy gas giants close to their stars, Jupiter is close to the top of the list. More material and it would become denser, so somewhere around these values lies the largest radius, and then radius reduction starts.

[Armchair Rocket Scientist]

No, Uranus and Neptune aren't called ice giants for those reasons. They got the name because their ice content is significantly higher than of Jupiter and Saturn. Most of their mass is hydrogen and helium, "permanent gases".

Ice giants are a subspecies of gas giants, not something equal on the hierachy.

Sorry, but most of the mass of ice giants is in fact ices.

http://en.wikipedia.org/wiki/Ice_giant

An ice giant is a type of giant planet composed largely of materials less volatile than hydrogen and helium.[1] It became known in the 1990s that Uranus and Neptune were really a distinct class of giant planet, composed of about 20% hydrogen, compared to the heavier gas giant's 90%.[1]

http://en.wikipedia.org/wiki/Uranus#Internal_structure

The total mass of ice in Uranus's interior is not precisely known, because different figures emerge depending on the model chosen; it must be between 9.3 and 13.5 Earth masses.[11][56] Hydrogen and helium constitute only a small part of the total, with between 0.5 and 1.5 Earth masses.[11] The remainder of the non-ice mass (0.5 to 3.7 Earth masses) is accounted for by rocky material.[11]

http://en.wikipedia.org/wiki/Neptune#Internal_structure

Neptune's internal structure resembles that of Uranus. Its atmosphere forms about 5% to 10% of its mass and extends perhaps 10% to 20% of the way towards the core, where it reaches pressures of about 10 GPa, or about 100,000 times that of Earth's atmosphere. Increasing concentrations of methane, ammonia and water are found in the lower regions of the atmosphere.[15]

[Science-Recon]

How big is Jupiter for a Gas Giant?

If a gas giant gets more than fourteen times the mass of jupiter, nuclear fusion occurs and it becomes a star.

Edited July 3, 2014 by Science-Recon
Number derp :P

[lajoswinkler]

Sorry, but most of the mass of ice giants is in fact ices.

http://en.wikipedia.org/wiki/Ice_giant

http://en.wikipedia.org/wiki/Uranus#Internal_structure

http://en.wikipedia.org/wiki/Neptune#Internal_structure

Huh, this is new to me. I remember reading about "mostly gases" inside them. I see now that Sandia Laboratories have made some progress on this, replicating the interior and tweaking our understanding of it.

It's surprising, though. I don't see why shouldn't there be a lot more H/He. Where did they go? Nebulas are objects that contain mainly those gases, and our system was made from a nebula.

The problem is that you can have various ratios of rock, ice and gas that could make your data look like there's a lot more ices than there really is. We simply don't know enough, but from a standpoint of evolution of Solar system, I'd think the ice ratio should be larger, but not dominant. Otherwise, how are we going to account for all the missing gases?

[magnemoe]

http://global3.memecdn.com/whenever-someone-tells-a-bad-joke_o_723438.jpg

I mean, going on a quick look here doesn't even say much as I don't think we know enough planets in the first place to say.

Remember that the extra-solar planets found tend to show more larger plantes as they are easer to find.

[YNM]

It's surprising, though. I don't see why shouldn't there be a lot more H/He. Where did they go? Nebulas are objects that contain mainly those gases, and our system was made from a nebula.

The problem is that you can have various ratios of rock, ice and gas that could make your data look like there's a lot more ices than there really is. We simply don't know enough, but from a standpoint of evolution of Solar system, I'd think the ice ratio should be larger, but not dominant. Otherwise, how are we going to account for all the missing gases?

Maybe that have something to do with the fact that rocky planets/bodies also contain a fair amount of trapped gas - silicate rocks are essentially trapping oxygen. Also, there are things like methane, water and such which are trapping some gasses into another kind of molecule. I mean, those giant planets all have some rocky core, right ?

WRT the main discussion : if you want to compare, this may help you a bit :

Note that the author says some sizes are only estimated by mass, means that people use some kind of standard density figures. The two largest in the solar system representation should be Jupiter and Saturn, respectively.