How did they figure out how the interior of the gas/ice giants?

[DerpenWolf]

So how did they figure out the interior layout of the gas planets? Basically I'm wondering what machinery and techniques they used to this out as I'm pretty amazed that they apparently didn't have trouble doing it.

[CaptainKipard]

Probably spectroscopy. That's also used to determine the composition of stars.

[Seret]

There's actually considerable uncertainty about the interior of Jupiter. Hopefully the Juno mission will shed a bit more light on it, you can see the battery of instruments it's got on its wiki page:

https://en.wikipedia.org/wiki/Juno_(spacecraft)

I guess ultimately they build up a model of the composition and structure by combining multiple sources of information. You could get a fair bit just from spectroscopy and density I'd imagine.

[Alchemist]

The thing is that spectroscopy can't reach deep - for stars it shows fotosphere/chromosphere/corona, but not the inner layers. With gas giants it wouldn't even reach as deep as a probe dropped in the atmosphere. But with some data about different element abundances and knowing the planet's density and magnetic field you can guess something about the core. As for the "metallic hydrogen" layer - you can conclude that there would still be mostly hydrogen at this depth (knowing how large the core should be) and there are ways to predict how it would act at such extreme pressures (that already goes into quantum mechanics).

So, most of that are models, supported by indirect observations.

P.S. Helioseismology is the science that observes and researches seismic waves on the Sun. Probably, similar observation could be possible for gas giants, too. And that's the closest we can get to observing internal layers.

[swamp_ig]

Heck, there's plenty of uncertainty about the insides of the earth, let alone other planets.

[78stonewobble]

The thing is that spectroscopy can't reach deep - for stars it shows fotosphere/chromosphere/corona, but not the inner layers. With gas giants it wouldn't even reach as deep as a probe dropped in the atmosphere. But with some data about different element abundances and knowing the planet's density and magnetic field you can guess something about the core. As for the "metallic hydrogen" layer - you can conclude that there would still be mostly hydrogen at this depth (knowing how large the core should be) and there are ways to predict how it would act at such extreme pressures (that already goes into quantum mechanics).

So, most of that are models, supported by indirect observations.

P.S. Helioseismology is the science that observes and researches seismic waves on the Sun. Probably, similar observation could be possible for gas giants, too. And that's the closest we can get to observing internal layers.

Just a little addition... Experiments to determine the properties of ie. hydrogen (or water) under similar pressures and temperatures. Basically smashing stuff together to create those pressures.

[CaptainKipard]

I think gravimetry can help as well, no?

[Alchemist]

I think gravimetry can help as well, no?

Gravimetry is chemical analysis method based on precipitation of the analyte and measuring its mass

But if you mean gravity field anomaly detection - these methods are good for solid bodies with uneven density distribution, but something liquid (gas giants, molten internal layers of Earth and other rock planets...) is too close to spherical symmetry... Maybe some indirect seismology measurements can be done this way, but not much more

[ZetaX]

Alchemist: no, his usage is correct, see e.g. http://en.wikipedia.org/wiki/Gravimetry .

[Aghanim]

Both of them is correct

[lajoswinkler]

You take a sample of something and then you squish it under a diamond anvil, and you do spectroscopic analysis of the sample during the squishing.

Then you do some computer simulations, and later publish your results. That's how it's done.

We don't know the details, but we get the big picture. Gas giants don't liquify in the center, they just get denser and denser and then the matter gets better and better at conducting electricity.