It has such a massive hydrogen atmosphere that the temperatures and pressures turn it into a metallic plasma below a certain depth (in literature referred to as the “Plasma Phase Transition”), and that plasma dissolved/ate the planet.
This metallic hydrogen plasma is basically indistinguishable from that found in stars. In fact, Jupiter is a Y-class brown dwarf star because of this morphology.
So there is a solid-ish core it’s just liquid plasma?
For all my youth I fantasized about what is under Jupiter’s clouds and always imagined it was a very dense metal.
So you’re saying that the solar system actually only has seven planets?
That’s a fuzzy number based on perspective.
Geologists usually argue for a morphology-based definition of planet over the current IAU dynamics-based one. The definitions that I’m presenting are an extension of the geological/morphological framing. This reflects my background as a planetary scientist vs an astrophysicist.
Dynamicists and astrophysicists still tend to prefer the existing definitions. They are concerned about angular momentum budgets, orbital dynamics, and interstellar consequences. To them, Jupiter isn’t a star because it isn’t hot enough to impact interstellar space and it isn’t massive enough to cause the sun to do much more than wobble. On a galactic scale, Jupiter doesn’t matter compared to the sun. To them, Pluto isn’t a planet because it’s too tiny and part of a larger debris cloud that damps its dynamical influence on the solar system. They are concerned with bigger things, and prefer to downgrade classifications to justify neglecting the influences of smaller bodies to make their math easier and less compute intensive. I want to be clear that this is still a valid and justifiable approach.
Geologists tend to prefer classifying objects based on what they are on the inside. Astrophysicists tend to prefer classifying objects based on their interactions in a larger system. As a result, geologists still usually refer to Pluto as a planet, and astrophysicists still usually refer to Jupiter as a planet.
“How many planets are in the solar system” is a question with a subjective answer based on your perspective, the story you’re trying to tell, and the problem you are trying to solve.
My question was silly, and I appreciate the serious and thought-out response.
This doesn’t seem to be the case, at least according to the brown dwarf wikipedia page which seems to use Jupiter as the yardstick for what isn’t a brown dwarf.
Not by my ctrl-f “Jupiter” on that page.
Jupiter is, however, the top of the list on wikipedia’s page for Y-type brown dwarfs.
This is a list of astronomical objects with the spectral type Y. They are a mix of brown dwarfs and planetary-mass objects.
Spectral type Y objects are not all brown dwarfs, they just have a similar elemental composition. Jupiter doesn’t have the mass to be considered a brown dwarf, they are 13-80 times the mass of Jupiter by definition.
That mass-based definition is outdated and does not consider recent observations of the interiors of Jupiter and Saturn made by the Juno and Cassini spacecraft. It is a reflection of cold-war era fusion chauvinism and is due to get an update. Jupiter is a star, Saturn straddles the boundary between star and planet.
Jupiter is a star, Saturn straddles the boundary between star and planet
I would suggest that a brown dwarf straddles the line between star and planet (the Wikipedia page begins with (“Brown dwarfs are substellar objects”) and that therefore Jupiter is, at best, straddling the line between star and planet, and therefore Saturn is solidly a planet.
I believe there is an object called a brown sub-dwarf which jupiter would clasify IF it wasn’t part of a planetary system that basically represents the smallest type of failed star, however since jupiter formed from a protoplanetary disc it is indeed a planet. It really is a bit of an issue with our classifications that they’re context dependant though. E.g the moon on its own could be a dward planet, earth orbiting at the same distance as pluto would also be a dwarf planet even with no other changes.
I like what you’re trying to do, but I disagree with merging brown dwarfs with planetary class objects because their interior structures and evolution are so different. Brown dwarfs are closer to stars than planets. The only difference between brown dwarfs and fusing stars is whether fusion occurs at the core. Planets are very very different in structure, morphology, and evolution.
This is how I suggest we classify things:
Let’s start by splitting things into two classes: planetary class and stellar class with Saturn at the boundary. This is a separation based on internal morphology and dynamics.
Stellar class objects then get split into two further subclasses: fusing stars (suns) and non-fusing stars (brown dwarfs).
Saturn exists at the boundary between the planetary class and the stellar class. Jupiter is solidly within the “brown dwarf” non-fusing stellar class of objects. The sun is a “fusing star”, which is also within the stellar class.
I mean, you can choose to define things however you want for your personal headcanon.
But for communication to work, people need to agree upon meanings. I’m guessing you don’t have a PhD in astrophysics, so your opinions are very unlikely to sway the consensus opinion on how these things are defined. And it’s their definitions that most lay people are going to take our cues from.
But even from the perspective of trying to come up with your own definitions…it’s rather poor practice to define things by presupposing your desired outcome. They didn’t define a planet vs dwarf planet by reference to Pluto, even though their desired goal was to exclude Pluto. They found actual criteria and used those. The definitions you’re giving, by stating “stellar class with Saturn at the boundary” does not work as a very good definition. Though again, you’re free to use that for yourself if you want…so long as you understand you will have severe difficulty communicating with others.
Still no, from the first sentence of your article
This is a list of astronomical objects with the spectral type Y. They are a mix of brown dwarfs and planetary-mass objects.
That’s mostly because of the outdated IAU definition of the boundary between those genres being at deuterium fusion. Deuterium has a low abundance, and its fusion happens very briefly and early in the lifecycle of these larger dwarfs. That flash is not significant in the grand scheme of what these objects fundamentally are, is highly theoretical and has never been observed, and is more a reflection of cold-war era fusion chauvinism than an actual morphological boundary between object classes.
See that also seems to be using it as a point of reference? It labels it a “Y-class analog”, and every other entry on the list is much heavier and hotter. I’m just not sure.
That’s mostly because the heavier and hotter the object, the easier they are to detect by various means. We’ve only recently been able to detect Y-dwarfs and measure their spectral/chemical properties. We still cannot detect Jupiter-size Y-dwarfs beyond our solar system. Jupiter is analogous to the chemical and spectral properties that we’ve seen in these larger dwarf stars. However, that’s only the outer atmosphere, and that alone isn’t enough to conclude that Jupiter is a star.
The Juno mission has used gravity data to confirm that Jupiter’s hydrogen plasma has fully dissolved what was once the planetary nucleus around which the hydrogen accreted. This is the interior transition to stellar morphology.
Similarly, the Cassini mission has used ring seismology (studying waves raised in the rings by planetary seismology and mass anomalies) to confirm that Saturn has a partially dissolved planetary core. Saturn is an object that can be classified as neither a planet nor a star, and represents a class of transition objects straddling the non-binary border between these genres of objects.
See the following previous comment threads where I’ve fleshed out this argument in more detail and with references:
I’ve heard a theory that there’s solid metallic hydrogen at the core from the absolutely immense pressure, but it hasn’t been confirmed.
Jupiter would have certainly had countless rocky, icy, and any other category of asteroid fall into it over the last several billions of years, so it’s not all hydrogen.
And I’m not sure if solid is the right word. It’s denser than solids we’re used to, but it’s not necessarily making any bonds between nearby atoms, so they might flow to some degree.
Though even if is solid at some point, it won’t necessarily be a sudden change from gas to solid or even gas to liquid to solid. The pressure is so high it might be more of a gradient than a surface like we’re used to here.
Here’s what I was taking about. The idea is under the right temps and pressures you’d get a lattice of single hydrogen atoms instead of hydrogen atom pairs. It could potentially be meta stable after being produced, but that’s still to be determined.
did you know that cashews come from a fruit
TIL gymnosperms are a thing.
Well almonds come from a peach-like fruit (I’ve broken open peach pits and found almond-like seed), so why not cashews do the same thing?
I don’t get it, is this some kind of ✨g a y✨ joke that I’m too straight to understand?
I don’t care, I’m just glad the debate over the rocky core was solved
NOOOO IT WASNT!!!
Its moons are clearly made of carbo based substances!!!
There’s something growing on Europa…
CAPTURED POST FORMATION
COPE
SEEEEETHE
Silliest thing I have ever heard? How would that even come about?
My understanding is the burgeoning gas giant eventually captures either an asteroid or remnant rocky debris which then grows through pebble accretion, but the gas giant would still be initially formed from mostly gases.
The (one) paper I read on this (while ignoring most of the confusing math bits) put the moons being captured when Jupiter was roughly 40% of its current mass.
So what would happen if you fell
First death is friction heat as you enter the atmosphere. Avoid it with a heat resistant vehicle or suit.
Next death is from extreme vibrations from the turbulence caused by supersonic winds. Avoid it with an aerodynamic and strong vehicle body that can withstand and stabilize in incredibly high winds.
Next death is lack of oxygen. But you probably have some oxygen system on that vehicle anyway just to get there.
Next is the freezing temperatures, around -145 C. Ok add some heating to your craft.
Next is the crushing pressure, passing 1000x earth’s atmospheric pressure and it just gets higher from there. Hope you didn’t use carbon fibre for your vehicle’s main structural integrity!
Then, if you’re not crushed anyways despite whatever you used to mitigate the previous one failing, there’s extreme heat to deal with again, just more of it this time. No known substance can withstand the heat, especially considering the pressure is still just increasing.
Further down is the metallic hydrogen layer. Assuming you haven’t already been converted to plasma, you probably will at this point.
And further down is the core that includes “rock” but I use the term pretty loosely.
Some of your atoms might eventually make it there but will likely spend a long time just blowing around in the atmosphere after they were vaporized.
Or as another user mentioned, ded
ded
Massive, passive ball
Or-Or-Orbital
