I mean, how do we get a certain quantity of gas matter to become an actual planet? Is there anything inside it? How is, say, Jupiter’s core?
In: Planetary Science
There is a certain amount of debris from comets and asteroids in the heart of a gas giant, in addition the pressure can create metallic hydrogen https://youtu.be/b-gCfHXNIVc
Gas, just like solids and liquids, has mass. This means that it generates gravity as well as gets pulled on by gravity.
So even a big cloud of gas will attract itself and clump together. Get enough gas and that gravity can be really strong and compress the clump a lot.
That said, solid matter does end up in those planets, they’re just mostly gas.
Gravity pulls matter together out of the planetary disk. The heavier matter falls towards the center, creating a core. The lighter gases make up the outer layers. Not much more to it than that.
We don’t know for sure what Jupiter’s core is made of, but it is surmised that it is made of heavy metals and/or molten rock.
“We” don’t get anything. That gas is the residue of the material left after the sun formed. I’m not sure where the confusion is – gas planets form the same way as rocky ones do – gravity works between any two particles with mass; two atoms of hydrogen or two atoms of iron. Since hydrogen is about 75% of the universe, it makes sense that most things will be made out of it (such as stars and gas giants).
It’s also a slight misnomer to call them Gas Giants.
Whilst the outer shells may be gaseous, the further down into the planet you go, and the higher pressure, the gases slowly turn to liquid and into solid. They’re not all gas all the way through.
the important difference between a gas giant and a rock/ice planet is normally mass. Gas giants are large enough to retain elemental hydrogen in their atmospheres(an escape velocity many times large the ambient thermal speed helps). Hydrogen, and to a lesser extent helium, is so overwhelmingly abundant that once that mass is reached it’s almost enivitable that the planet will be mostly hydrogen. The elements that make up earth will probably be there in Jupiter’s core along with things like hydrogen and helium that would be gaseous on earth but Jupiter’s huge atmosphere causes enough pressure to liquify or solidify them.
The heavy elements making up the planet would have all fallen into the center. Just like on our own planet we believe the core is made mostly of nickel and iron.
Outside of that is where all the gasses (mostly hydrogen) are collected and add a significant portion of the planet’s mass and volume
The initial formation of the planets would be much as our own and the other terrestrial planets.
Once the sun started undergoing fusion, the light pressure pushed all of the gasses to the outer solar system, where it could form into gas giants, leaving the inner planets rocky.
In the following few hundred million years, the solar system stabilized to how it is now, none of the outer planets being dropped into the inner solar system to make a “hot Jupiter” like we have observed in other solar systems.
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