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Are Small Rocky Worlds Naked Gas Giants?

Soulskill posted more than 2 years ago | from the elliptical-streaking dept.

Space 91

astroengine writes "The 'core accretion' model for planetary creation has been challenged (or, at least, modified) by a new theory from University of Leicester astrophysicists Seung-Hoon Cha and Sergei Nayakshin (abstract). Rather than small rocky worlds being built 'bottom-up' (i.e. the size of a planet depends on the amount of material available), perhaps they were once the cores of massive gas giant planets that had their thick atmospheres stripped after drifting too close to their parent stars? This 'top-down' mechanism may also help explain how smaller worlds were formed far from their stars only to drift inward toward the habitable zone."

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91 comments

Well then... (2, Funny)

reeno49 (1558221) | more than 2 years ago | (#37431252)

I imagine this excludes Earth, but if not it would explain a lot of the smells.

Re:Well then... (-1)

Anonymous Coward | more than 2 years ago | (#37431278)

Suck on my penis, you will!

Re:Well then... (2)

hairyfeet (841228) | more than 2 years ago | (#37432968)

Put that little green thing away Yoda, nobody is impressed.

As for TFA while its nice to make all these little guesses how will we know if any are right when it would take a couple of dozen lifetimes at top speed for a probe to get anywhere close to one of these?

That is why I always find stories like this depressing. its like "Hey here is another cool thing you'll never set foot on or even see video of isn't that great? Oh and its probably full of three titted hookers and beer, too bad you'll never get to find out huh?"

As someone who grew up on Battlestar and Star trek these articles just remind me of how much cool stuff there is out there that we will NEVER get to see close up in my lifetime. That really sucks.

Re:Well then... (1)

mywhitewolf (1923488) | more than 2 years ago | (#37436228)

considering we went from being stuck on to the ground to getting in space within a lifetime, i wouldn't write off long distance space travel just yet.

outlook doesn't really look that great though..

Re:Well then... (0)

macraig (621737) | more than 2 years ago | (#37431332)

Stop eating at cheesy Mexican restaurants and stop tipping the cows. That'll solve the problem for all of us.

Re:Well then... (0)

Anonymous Coward | more than 2 years ago | (#37436970)

Why does this comment get modded down when the one just below it earns a +3 Funny? This is no less funny and it's even a bit less vulgar.

Moderators, stop playing favorites with your buddies. Never heard of tribalism? It sucks.

Re:Well then... (3, Funny)

Penguinshit (591885) | more than 2 years ago | (#37431658)

I once sat next to a gas giant on an airplane. Thank God it was just a short commuter flight.

Re:Well then... (0)

dkleinsc (563838) | more than 2 years ago | (#37432122)

Yo mamma is so fat that she was mistaken for a naked gas giant!

Re:Well then... (0, Troll)

Anonymous Coward | more than 2 years ago | (#37432400)

For fuck's sake. Occasionally I see an interesting thread like this, but despair that the first 50 comments are always a bunch of unfunny jokes. Fuck. Stop it. It's not funny.

Any sensible reply gets buried by crap like this. "Haha, gas and smells" "Hahah, cow tipping", "Hahah, your momma", "Hahah, gas giant", "Hahaha, your crust is showing".

Look, none of those replies were witty. They were, at best, stupid. I used to come to Slashdot to actually find more detail about the science behind the article, but now it just puts me off even reading.

Re:Well then... (0)

Anonymous Coward | more than 2 years ago | (#37432776)

Slashdot is broken. I have Funny way way downrated in settings, yet the Score:0 Funny and its replies are listed above the Score:2 top post later.

Re:Well then... (1)

MightyYar (622222) | more than 2 years ago | (#37433966)

Slashdot always had stupid, juvenile humor mixed in with the more sophisticated gems, obscure sci-fi references, jokes in psuedo-code, and occasional guy who actually has some experience with the subject at hand. Perhaps you are just getting older?

Re:Well then... (1)

mywhitewolf (1923488) | more than 2 years ago | (#37436244)

its not that those things aren't around anymore.. its the amount of crap you have to wade through to get to the goods that seems to be increasing.

Anti-darwinism... (0, Offtopic)

aleckais (1457189) | more than 2 years ago | (#37431290)

Here one can generalize: instead of being improved monkeys we may be restrictions of something higher. And entropy hints at our downward progress.

Re:Anti-darwinism... (1)

EdZ (755139) | more than 2 years ago | (#37431302)

From savant rock-knappers to mere savage spaceship-builders, then?

Re:Anti-darwinism... (1)

Anonymous Coward | more than 2 years ago | (#37431308)

Well, that "theory" is wrong. A gas giant at Earth's orbit would retain its entire atmosphere. Pluto, well, not a gas giant?

It's not even a hypothesis.

Re:Anti-darwinism... (1)

rossdee (243626) | more than 2 years ago | (#37432600)

Pluto isn't even a planet any more :(

Re:Anti-darwinism... (0)

Anonymous Coward | more than 2 years ago | (#37432660)

In what way is a dwarf planet not a planet?

And as an analogy:
Do you think that Phil Fondacaro is a human or not?

Re:Anti-darwinism... (-1)

Anonymous Coward | more than 2 years ago | (#37431378)

And this begs the question of entropy and the definition of life. Anyone that has spent time with a 3 year old knows they generate a LOT of entropy. It all has to do with the size of the system, the frame of reference. Which planet has more entropy, Earth or Mars? Duh, Earth. Life is eroding and destroying the surface, creating dynamic weather patterns, and pushing things all over. An individual may have less entropy, but life over time definitely increases entropy. Thermodynamics actually _favors_ life.

Re:Anti-darwinism... (0)

Anonymous Coward | more than 2 years ago | (#37431408)

Hey, I'm non anonymous, I'm UrgentUnguent.

Re:Anti-darwinism... (1)

StuckInSyrup (745480) | more than 2 years ago | (#37435480)

You don't understand the theory of evolution.
We are no improved monkeys. Every species living today is the pinnacle of its own evolution. Our minds and civilisation are a glitch, a side product, not a evolutionary goal. The only goal of evolution is survival and reproduction.

Re:Anti-darwinism... (0)

Anonymous Coward | more than 2 years ago | (#37439446)

Our minds and civilisation are a glitch, a side product, not a evolutionary goal.

Thus, what you (and I) say is a glitch, a side product. Should we reason at all?

Re:Anti-darwinism... (1)

TWX (665546) | more than 2 years ago | (#37441542)

You don't understand the theory of evolution.
We are no improved monkeys. Every species living today is the pinnacle of its own evolution.

I'd bet that most of the time, "monkeys" is used instead of "primates" because of the derision that started around the time of the Scopes Monkey Trial, and the nomenclature stuck.

Wait a tic... (2)

billsayswow (1681722) | more than 2 years ago | (#37431298)

I've had this idea before. Thought that's what happened to Pluto, when I was was in 3rd grade. I don't see anyone nominating me for a Nobel prize!

Re:Wait a tic... (3, Funny)

Anonymous Coward | more than 2 years ago | (#37431688)

That's what you get for not publishing your idea in a peer-reviewed science journal! Stupid 3rd graders.

Re:Wait a tic... (1)

shadowofwind (1209890) | more than 2 years ago | (#37432262)

No, that's what he gets for not recognizing the fundamental difference between a 'rocky world' and a small ball of ice.

Hot Jupiters? (3, Insightful)

clonan (64380) | more than 2 years ago | (#37431306)

For a long time the only planets we found were 'hot Jupiters'. Jupiter sized planets very close to their star (inside Mercury's orbit).

Why weren't these planets stripped of their atmosphere?

Re:Hot Jupiters? (1)

c0lo (1497653) | more than 2 years ago | (#37431388)

For a long time the only planets we found were 'hot Jupiters'. Jupiter sized planets very close to their star (inside Mercury's orbit).

Why weren't these planets stripped of their atmosphere?

Because nobody's there to sing "You can leave your hat on"?

Re:Hot Jupiters? (1)

AliasMarlowe (1042386) | more than 2 years ago | (#37435560)

For a long time the only planets we found were 'hot Jupiters'. Jupiter sized planets very close to their star (inside Mercury's orbit).

Why weren't these planets stripped of their atmosphere?

Because nobody's there to sing "You can leave your hat on"?

From a quick perusal of the article, one group of sentences stands out:
"The final fate of the clumps and thus the outcome of the simulation in its entirety does depend on the cooling prescription (as also expected based on analytical models of Nayakshin 2010c,b,a), initial conditions, e.g., the disc mass, and missing physics (e.g., exact radiative transfer, and a better opacity, dust growth and fragmentation models) not yet included into the code. If radiative cooling of clumps is not suppressed sufficiently strongly at high densities, they may cool and collapse into massive gas giant planets or low mass brown dwarfs (Stamatellos & Whitworth 2008). Inward migration of such objects would disrupt them only if they migrate very close to the star, e.g., sub-AU distances that we do not resolve in our simulations."
In other words, they adopted certain assumptions which may not prove tenable, and which have a definite effect on the result of their simulations. Possibly courageous, possibly foolhardy.

Of course, had they limited their discussion to Wolf-Rayet stars [wikipedia.org] , then stripping proto-Jupiters to leave only a rocky core would have been quite plausible. Such stars have extremely violent solar winds, and blow off their own upper layers during formation. However, Wolf-Rayet stars are an extreme of type O stars [wikipedia.org] , and are thought to result in a supernova within 10^5 to 10^6 years of formation, so they are particularly short-lived. The authors were treating regular stars of mass not dissimilar to our Sol, so their conclusions are, to say the least, speculative.

Re:Hot Jupiters? (3, Interesting)

Anonymous Coward | more than 2 years ago | (#37431394)

I think the general idea is that these would in fact be proto-planets. Essentially any of these gas giants rotating close to their suns could evolve into an Earth like planet. The question would be how old are the systems that we are finding these gas giants close to their stars? If they are all old systems then I doubt the theory will hold up. If they are mainly younger systems then it's possible. There has to be more than one way for planets and moons to form if this theory is true because the theory wouldn't explain the Earth's moon as well as most other moons. It would explain iron cores and could potentially explain the differences between the Earth and Mars if say the Earth started out as a gas giant and Mars was made up of asteroid like debris. Earth having an iron core and Mars having a less defined core. Mars has a lot of surface iron but lacks a strong magnetic field so it lacks a large iron core. If the near star gas giants are proto Earths then it raises the likelihood of large numbers of Earth like planets since near star gas giants are so common. Just look at older systems for Earth like planets.

Re:Hot Jupiters? (3, Informative)

GreenTom (1352587) | more than 2 years ago | (#37431402)

RTFA (A=abstract, since the article is behind a paywall)...the abstract doesn't say that gas giants formed, then were stripped. It suggests the protoplanatary disk breaks up into clumps of gas and dust, and that the clumps that come too close to the star are stripped of their gas. I think all this happens long before the dust clouds condense into planets. At least from the abstract, all they seem to be saying is that the same original dust clouds could become rocky planets or gas giants, depending on if they're disrupted or not.

Re:Hot Jupiters? (1)

Anonymous Coward | more than 2 years ago | (#37431458)

IANAA (astronomer), but it seems that the thrust of the article is on the homogeneous formation of protoplanets from gas and dust and their migration to stable positions rather than the stripping of atmospheres from gas giants. In fact, "stripped" gas giants have been theorized for quite some time and are referred to as "chthonian planets [arxiv.org] ."

Re:Hot Jupiters? (1)

mikael (484) | more than 2 years ago | (#37431460)

General history of the universe is that each galaxy starts out as super-massive red giants which rapidly burn up their fuel and explode, forming new but smaller stars. Eventually the remains reform into stars and planets.

I guess the iron from the fusion process and the heavier elements from the supernova process would end up forming the new stars and planets.

Re:Hot Jupiters? (0)

Anonymous Coward | more than 2 years ago | (#37432634)

Wouldn't a star with the massive of a galaxy just collapse into a black hole?

Re:Hot Jupiters? (1)

mywhitewolf (1923488) | more than 2 years ago | (#37436738)

like whats found in the center of (almost?) every galaxy? yes, yes indeed... not all that matter gets turned into a black hole though, the left overs get turned into stars & planets.

Re:Hot Jupiters? (4, Informative)

arcctgx (607542) | more than 2 years ago | (#37431674)

RTFA (A=abstract, since the article is behind a paywall)

Never fear, arXiv delivers: http://arxiv.org/abs/1010.1489 [arxiv.org]

Re:Hot Jupiters? (1)

Holammer (1217422) | more than 2 years ago | (#37431522)

For a long time the only planets we found were 'hot Jupiters'. Jupiter sized planets very close to their star (inside Mercury's orbit).

Why weren't these planets stripped of their atmosphere?

Because those are young planetary systems? Just like ours was some 4.5 billion (give or take) years ago. Sounds like a reasonable guess.

Re:Hot Jupiters? (1)

Anonymous Coward | more than 2 years ago | (#37432298)

Your guess is wrong.

Magnetic field of planets keeps their atmosphere in place, to some extent. Basically, it prevents ionized gases from escaping. Without a magnetic field, Earth would be like Mars, lifeless and almost without atmosphere. It is believed that Mars lost its atmosphere when its magnetic field disappeared.

For light elements, like H or He, you need much stronger gravitational force to keep the non-ionized molecules down. Something like Jupiter.

This brings us back to Jupiter. Jupiter is well within what the abstract tells us when the atmosphere is to be blown off. Clearly, Jupiter is not losing its atmosphere precisely because,

1. it has a large enough mass not to lose H and He and the like
2. it has a VERY STRONG magnetic field that recycles any ionized gas.

So, obviously that paper is wrong on many levels. Planets don't lose their atmosphere because it is "blown away" - the magnetic field would have to be weak enough to allow local solar storms to leach the atmosphere. That is unlikely from Jupiter sized planets. The alternative is that the local star is very violent.

Anyway, our only model for solar system formation is our own. We do not have even remotely complete picture of extrasolar planets so all that paper can talk about is guesses at best.

Re:Hot Jupiters? (1)

dryeo (100693) | more than 2 years ago | (#37432406)

Magnetic field of planets keeps their atmosphere in place, to some extent. Basically, it prevents ionized gases from escaping. Without a magnetic field, Earth would be like Mars, lifeless and almost without atmosphere. It is believed that Mars lost its atmosphere when its magnetic field disappeared.

We

Re:Hot Jupiters? (1)

Fieryphoenix (1161565) | more than 2 years ago | (#37431816)

An explanation compatible with this new idea would be they may planets in a system not be old enough for the process to have completed.

Re:Hot Jupiters? (1)

osu-neko (2604) | more than 2 years ago | (#37431882)

Why weren't these planets stripped of their atmosphere?

Some of them quite clearly are being stripped, undergoing significant mass loss as their stars blast away at their atmosphere. Remember, for most everything you look at, it is not in its end-state.

Re:Hot Jupiters? (1)

Anonymous Coward | more than 2 years ago | (#37433058)

The reason we only found hot Jupiters for a long time is because those are by far the easiest to discover. It doesn't mean there are more hot Jupiters than earth-like planets. It simply means we did not have the precision yet to see the earth-like planets. When we looked at a star, we either saw a hot Jupiter, or we saw nothing. Anything smaller or further away than a hot Jupiter did not cause enough wobble in the parent star to notice.

Wait a minute... (1)

SigmundFloyd (994648) | more than 2 years ago | (#37431382)

modified > challenged

no?

What about all these new gas giants? (1)

MichaelSmith (789609) | more than 2 years ago | (#37431416)

Many of these extrasolar gas giants are in extremely small orbits very close to a star. So how could Earth and Mars have lost huge atmospheres?

YES SCIENTIST ARE TAKING US FOR A RIDE (-1)

Anonymous Coward | more than 2 years ago | (#37431434)

They can't really prove there is a distant planet revolving around a distant world. A wiggle here and glimmer there it's just gas moving around. But they've somehow made up math to get us believing there are planets moving. By the time you learn their theories it's too late. You'll be old or they'll have changed them.
Science use to think Jupiter had insane gravity. Next they'll tell us you can't sale around neptune in a submarine. But chances are you will be able too.

Re:YES SCIENTIST ARE TAKING US FOR A RIDE (1)

Teancum (67324) | more than 2 years ago | (#37432118)

Is that sail or sale? Or is that a sail sale? I suppose you can hold a sale around Neptune in a submarine having fun on Triton, especially if something like the Battleship Yamato [wikipedia.org] actually makes the trip into space. If a battleship can do that, I suppose a submarine can too.

I also suppose these "scientists" haven't been able to really prove the existence of China to your satisfaction either. Yes, Marco Polo brought back some amazing legendary stories and a few trinkets he claims to have come from there. I guess the theory of China is just the figment in the imaginations of a whole bunch of people too, in spite of what the Sam Walton family has done with more trinkets supposedly discovered from that mythical place.

Re:YES SCIENTIST ARE TAKING US FOR A RIDE (2)

Caesar Tjalbo (1010523) | more than 2 years ago | (#37432978)

They can't really prove there is a distant planet revolving around a distant world.

You seem to have bought the 'distant world' theory, you're this close in believing the earth isn't flat. Do your parents know this?

Re:YES SCIENTIST ARE TAKING US FOR A RIDE (1)

mark-t (151149) | more than 2 years ago | (#37434250)

There's no made up math involved... it's an irrefutable conclusion from simple observation, plus judicious application of occam's razor. If you can come up with a simpler explanation that actually accounts for the observations ("just gas moving around" wouldn't cut it, I'm afraid... because that doesn't explain all the observations), then you may be in line for a nobel prize.

Continuing Gas Giants remark... (2)

fuzzyfuzzyfungus (1223518) | more than 2 years ago | (#37431448)

Your crust is showing. Slut.

Re:Continuing Gas Giants remark... (1)

skine (1524819) | more than 2 years ago | (#37431732)

Richie, eat your crust!

Re:Continuing Gas Giants remark... (0)

Anonymous Coward | more than 2 years ago | (#37431856)

she's wet between the ridges... and trembling (tremor-ling???)

Re:Continuing Gas Giants remark... (0)

Anonymous Coward | more than 2 years ago | (#37432090)

And you're oozing thru the cracks.

Are Small Rocky Worlds Naked Gas Giants? (1, Redundant)

florescent_beige (608235) | more than 2 years ago | (#37431452)

I don't know. Why ask me? What on Earth makes you think I would know? Go ask an expert. Geesh.

Trivial? (1)

Pino Grigio (2232472) | more than 2 years ago | (#37431462)

How does this square with the idea that gas giants have materials like metallic hydrogen at their cores? I can see how accretion can occur without the necessity for a rocky core, and I can see how it would occur with one. Either way, isn't this hypothesis kind-of trivial in its conclusion? Matter accreted more matter. Equilibrium is reached. Constituent parts - gas, solid, ice are determined based on many variables. There is a centre of gravity. That's all.

(Disclaimer: I might have misunderstood the point!).

Re:Trivial? (4, Interesting)

Teancum (67324) | more than 2 years ago | (#37431512)

How does this square with the idea that gas giants have materials like metallic hydrogen at their cores? I can see how accretion can occur without the necessity for a rocky core, and I can see how it would occur with one.

There isn't necessarily a dilemma here as the theory still can be consistent for both results, in terms of rocky "terrestrial" bodies being naked gas giants and "traditional" gas giants still having a metallic hydrogen core.

Planets like Jupiter and Saturn, while certainly the bulk of their current mass is Hydrogen and Helium, they do have other elements that comprise their structure and more than likely you would find at the core of these planets a "rocky" core that would include Iron, Nickle, and other elements that would be more identifiable with what we have here on the Earth. The question would be how large would that tiny "rocky" core would be if you stripped off the outer gaseous layers.

The problem with this theory is mainly how you go about stripping off that outer layer. The presumption here is that objects close in to a star like the Earth, Mars, and Venus are at the moment would have had this outer "shell" being stripped off at some point in the distant past as the Solar System was being formed.

Highly unlikely theory (5, Interesting)

gstrickler (920733) | more than 2 years ago | (#37431530)

As this calculation for CoRoT-2b [slashdot.org] indicates, at 6M tons per second, a hot super-Jupiter would need more than 39B years (~3x the age of the universes) to be "blown/boiled away". Jupiter is ~1/3 the mass of CoRoT-2b, so at 6MT/s, it would last 13B years. The rate of loss of atmosphere would have to be at least a factor of 10 greater than on CoRoT-2b, or greater than 60MT/s just for a Jupiter mass planet to to reach an Earth mass core in 1.3B years. Our solar system is estimated to be ~5B years old and that Earth and Mars both appear to have been rocky for more than 2B years, so 1.3B years to blow off an atmosphere seems to be a generous estimate of quickly it must have happened.

Given that our sun is only converting ~600M tons/sec of hydrogen into ~594M tons of helium, a net loss of 6MT/s, therefore a Jupiter mass planet would need to be receiving a enough of the solar radiation to blow off 60MT/s. Yes, E=mc^2, and c^2 is large, but you're still talking about a lot of mass to move out of notable gravity well (first out of the Sun's gravity well, then move more mass out of Jupiter's gravity well). If jupiter were in earth's orbit, would it receive enough solar radiation to lose 60MT/s? Not from solar wind, the total solar wind [wikipedia.org] mass is ~1.85MT/s. even if all 1.8MT were directed at Jupiter and Jupiter had no magnetopause to protect it from the solar wind, 1.8MT/s would not strip 60MT/s of atmosphere. So you have to come up with a theory where the EM radiation causes the the planet to eject it's own atmosphere, which is still going to be virtually impossible [wikipedia.org] .

Re:Highly unlikely theory (0)

Anonymous Coward | more than 2 years ago | (#37431806)

Sol is a second generation sun.

Re:Highly unlikely theory (5, Interesting)

Teancum (67324) | more than 2 years ago | (#37432100)

The Sun (Sol in Latin and derivative languages) is more like a 3rd or 4th generation star in terms of material recycled from previous stars that has gone through supernovas and reformed to become new stars. At least that is where exotic elements like Uranium, Gold, Silver, and just about everything heavier than Oxygen have come from.

I presume the objection here is that 1st generation stars (which at this point are very old stars which likely have had any planets around them ripped off simply by passing near other stars on any journey they have made going around the galactic core or even a small globular cluster) would behave differently than something you would see around the Sun. Certainly compounds more exotic than water would be quite rare and even water would be minor.

Still, of the planets that are being considered with this model, I think the GP post is fairly on spot in terms of skepticism on this theory. EM radiation alone is unlikely to be able to provide the energy needed to strip gas giants of their atmosphere, where I think you would need some kind of gravitational actor as well. The problem with that theory is it introduces a 3-body problem and requires an explanation for where that object went, whatever it was. The 3-body problem is a big deal because at the very least any planet would likely be in a highly elliptical orbit where the presence of that gravitational anomaly would leave some evidence behind. I don't think that is necessarily a good idea either.

The environment in a stellar nursery would be rather complex, where perhaps a "nearby" neutron star emitting x-rays and other complex aspects of the environment might also be a factor. The ignition sequence of what happens with a star finally starts the fusion process could also be a factor here, where there might be some added complexity in the protostar cloud before the star finally settles down into a stable main sequence pattern. A brief (on the scale of a typical star's lifetime) period of intense radiation and/or stellar wind when this ignition starts might be something to consider. Current theory suggest this is a rather benign event where gravity merely starts compressing the gasses that gradually start producing more fusion before it becomes stable, but that might be mistaken. For small stars (stellar class M objects, for instance) that may be the case, but larger stars certainly do have their own peculiar life cycles anyway so the "birth" of a large star might be nearly as dramatic as its death, just as the death of class M stars is rather wimpy too.

Re:Highly unlikely theory (0)

Anonymous Coward | more than 2 years ago | (#37432678)

It may be that Earth's atmosphere is remnant of a gas giant one, as the mass of the planet wasn't enough to keep the gases from escaping, until, well, most of it escaped and condition where the loss is minimal reached. Jupiter is both colder (less gas with escape velocity) and has much more massive core. So what if jupiter was closer to Sun and started loosing a lot of hydrogen due to heating alone?

Re:Highly unlikely theory (1)

Teancum (67324) | more than 2 years ago | (#37436390)

The gravitational forces alone on Jupiter are more than enough to hang onto the full atmosphere it currently holds, even if it were at the position that the Earth is at. Yes, even if Jupiter was "heated" to the temperatures that we find on Earth today from solar flux radiation, the Hydrogen gas would do just fine. Some would be pulled off due to solar wind and increased thermal pressure, but it would take the lifetime of the Universe before it would be something you would notice.

It is for this reason I was agreeing to the original grandparent post about the skepticism in terms of this particular theory. There must have been some other factor than just pure radiation from the Sun due to nuclear fusion to account for the lack of significant quantities of Hydrogen and Helium in our atmosphere.... presuming that the Earth started out as a gas giant even the size of Neptune much less Jupiter. Those gasses, even though they might eventually be driven off, also contribute mass to the planet and in and of themselves help to keep the atmosphere of the planet in place.

BTW, most of the current thermal radiation near Jupiter comes from Jupiter itself rather than from the Sun... left over residual heat from its formation billions of years ago. In order for a planet the size of Jupiter to completely lose its atmosphere through thermal radiation, it would have to be inside the orbit of Mercury to make a difference. Do the math.... the GP poster certainly did.

Re:Highly unlikely theory (1)

Thing 1 (178996) | more than 2 years ago | (#37433876)

At least that is where exotic elements like Uranium, Gold, Silver, and just about everything heavier than Oxygen have come from.

Agree with everything else you said -- but it's Iron, not Oxygen, that is the heaviest element that can be created through stellar fusion processes.

Re:Highly unlikely theory (1)

Teancum (67324) | more than 2 years ago | (#37436354)

Oxygen is about the heaviest element that was left over from the Big Bang in any substantial quantity, which is what I was referring to. Most of the heavier elements like even Carbon or Sodium needed nuclear fusion processes in order to form them in the quantities we see in the Solar System today.

Yes, I do realize that Iron is at the "bottom" of the fusion well in terms of what element starts supernovas. Perhaps I should have made that more clear what I was trying to suggest here. Likely nearly every element on the periodic table was in the early universe (including the recently discovered elements), but the dominance of Hydrogen and Helium with traces of some of the lighter elements is pretty much all there was originally.... certainly not enough material to form a rocky core even in a very large and relatively concentrated interstellar nebular cloud when the universe was formed.

Re:Highly unlikely theory (1)

Thing 1 (178996) | more than 2 years ago | (#37445868)

Ah, okay, thanks -- you are generally correct, so that stood out to me. Thanks for explaining!

Re:Highly unlikely theory (0)

Anonymous Coward | more than 2 years ago | (#37432244)

RTFA (or abstract). It does not suggest that the gas is "blown/boiled away".

Re:Highly unlikely theory (4, Informative)

gstrickler (920733) | more than 2 years ago | (#37432708)

I read the article and the abstract. Apparently you failed to comprehend it, go read it again. They talk about stripping the atmosphere/gases from a 7.5 Earth Mass (Me) clump at ~8 AU. So, my example still applies. The details may vary a bit, but a 7.5Me clump is going to have a significant gravity well/escape velocity, and for it to absorb enough solar radiation @ ~8 AU is beyond unbelievable, the math just doesn't work.

Re:Highly unlikely theory (1)

tragedy (27079) | more than 2 years ago | (#37432380)

Since a super-Jupiter would probably have a higher escape velocity than Jupiter, it might be easier to strip atmosphere from Jupiter than from a super-jupiter. Also, I'm assuming that solar wind that hits a gas giant dead on probably results in net absorption rather than net loss of atmosphere and that most of the loss occurs where the solar wind hits the sphere of the planet at a tangent. Jupiter does, presumably (unless the material is very much denser), have a smaller circumference than a super-jupiter, so that might slow the loss by a bit. Of course, none of that makes a huge difference, like you said, it would still take close enough to forever that it couldn't have happened yet for a planet like Earth to have once been a Jupiter.

Re:Highly unlikely theory (1)

sFurbo (1361249) | more than 2 years ago | (#37433054)

. Jupiter does, presumably (unless the material is very much denser), have a smaller circumference than a super-jupiter, so that might slow the loss by a bit.

The circumferences will be about the same. Around the mass of Jupiter, the extra gravity from more material balances out the volume of the extra material. Gliese 229B has 20 to 50 times the mass of Jupiter, but around the same size.

Re:Highly unlikely theory (0)

Anonymous Coward | more than 2 years ago | (#37434058)

Yes but, "Where baby come from?" "How woman get pregnant?"

Magic. Fucking magic. (0)

Anonymous Coward | more than 2 years ago | (#37431636)

And they magically entered stable orbits afterward. Of course.

Re:Magic. Fucking magic. (0)

Anonymous Coward | more than 2 years ago | (#37432338)

And they magically entered stable orbits afterward. Of course.

You say that as if a stable orbit is something hard to achieve...it's not.

Inside a gas giant (1)

DNS-and-BIND (461968) | more than 2 years ago | (#37431728)

I thought the solid surfaces of gas giants weren't rocky at all, but rather hydrogen compressed to a metallic state under extreme pressure? Without the pressure, the gas would melt and then boil away. I thought rocky planets were basically accretions of asteroid junk.

Re:Inside a gas giant (1)

osu-neko (2604) | more than 2 years ago | (#37431898)

I thought the solid surfaces of gas giants weren't rocky at all, but rather hydrogen compressed to a metallic state under extreme pressure? Without the pressure, the gas would melt and then boil away.

At the surface, that's probably true. It does not contradict the notion, still generally held to be true, that there's a rocky core underneath that.

Re:Inside a gas giant (1)

dotancohen (1015143) | more than 2 years ago | (#37435386)

I thought the solid surfaces of gas giants weren't rocky at all, but rather hydrogen compressed to a metallic state under extreme pressure? Without the pressure, the gas would melt and then boil away.

At the surface, that's probably true. It does not contradict the notion, still generally held to be true, that there's a rocky core underneath that.

Both you and the GP's notions are based on speculation an computer modeling. The Juno craft will soon be leaving for Jupiter, and hopefully will help us understand what really is at the core.

I once met a naked gas giant! (1, Funny)

Dr. Spork (142693) | more than 2 years ago | (#37431912)

Ah wait, it was just your mom.

Re:I once met a naked gas giant! (0)

Anonymous Coward | more than 2 years ago | (#37432038)

So... did you do her anyway?

Diamonds, Garnets, and Granulites? (1)

bill_mcgonigle (4333) | more than 2 years ago | (#37432278)

At those pressures, we ought to see a planet covered in diamonds, garnets, granulites, etc. - very high temperature metamorphic rocks. If the planet is made of other types of rock, then there probably wasn't that much pressure on it when the rock formed.

Disclaimer: I am not a xenogeologist.

Are ALL small rocky worlds naked gas giants..? (1)

Maritz (1829006) | more than 2 years ago | (#37432610)

This seems to be the title of this post. Very unlikely don't you think. Are some? Sure, why not.

The general rule of thumb is that volatiles like water/hydrocarbons/helium get evaporated and blown out by the nascent star at the centre of a proto-planetary disk. So, many rocky planets will form from the remaining silicate and other non-volatile materials (such as Iron) that are left after most of the volatiles are gone. Will some gas giants migrate inwards and have their atmospheres evaporated and blown off..? Can't think of any reason why not especially given the number of hot jupiters we've discovered out there.

Why this post/article would bother suggesting that ALL rocky planets MUST be formed this way is beyond me, seeing as the authors themselves don't appear to be making this assertion. Whether a planet forms this way would depend on all sorts of factors, such as the composition of the proto-planetary disk and the temperature of the star among other things.

I'm also quite sure [wikipedia.org] this isn't the first time I've heard this idea.

SMTS (1)

Kevin Fishburne (1296859) | more than 2 years ago | (#37432702)

Show me the simulation. It would make a nice screen saver and maybe explain the theory to those who haven't read TFA or imagined it previously.

I've found some genuinely hilarious jokes on /. (0)

Anonymous Coward | more than 2 years ago | (#37432728)

But not in the comments for this article.

undersized stars (2)

roman_mir (125474) | more than 2 years ago | (#37432766)

Gas giants are wannabe stars. They are Pauly Shores of the night skies.

Earth could be considered a Gas Giant (2)

Quick Reply (688867) | more than 2 years ago | (#37433274)

The Earth surrounded by Oxygen gas (and other gases) in the atmosphere, the only difference to us is that our eyes have evolved to see through the wavelength of oxygen making it appear 'invisible', but from the hypothetical alien point of view, an alien looking at earth might not have the eyes to see through the Oxygen and it would look like any other gassy planet from their perspective.

Maybe the technology can be developed to look through the gasses of other planets to see inside in the same way we can see though oxygen.

Sorry if there are any scientific errors in my theory, I'm not an expert, but unlike most the other posters on Slashdot, I don't even pretend to be one.

Re:Earth could be considered a Gas Giant (1)

mark-t (151149) | more than 2 years ago | (#37434352)

Nice theory, but no... at least with regards to your alien concept.

A substance is considered opaque when light does not pass through it.

Light *DOES* pass through our atmosphere. It is translucent to many frequencies (heck, it's even translucent to visible light), and it absorbs many others. I do not think it actually reflects any EM frequencies, however, except those that hit it at a sufficient angle to be totally reflected due to its index of refraction.. To an alien whose eyes could only see in such frequencies, our planet would thus appear like a black ball, indistinguishable from the blackness of space except for its gravitational pull.

Re:Earth could be considered a Gas Giant (2)

Gavagai80 (1275204) | more than 2 years ago | (#37434438)

We can't see through the atmosphere of Venus, but that doesn't make Venus a gas giant. The atmospheres of Venus and Earth are extremely thin compared to the radius of the planets themselves, whereas Jupiter's atmosphere is bigger than its rocky core. Also by the way, Earth's atmosphere is mostly nitrogen.

Half an explanation (1)

arisvega (1414195) | more than 2 years ago | (#37433510)

perhaps they were once the cores of massive gas giant planets that had their thick atmospheres stripped after drifting too close to their parent stars?

(emphasis mine)

Let's assume they did. How did they drift back out?

Re:Half an explanation (1)

mark-t (151149) | more than 2 years ago | (#37434190)

That phrase sort of had me puzzled as well.... planets don't just "drift"... they are in (relatively) stable orbits around their parent star, and it's my understanding that generally speaking, that's roughly where the planet is born - out of the matter in the accretion disc of the parent star that had a sufficient tangential velocity to the star to sustain an orbit at that distance.

Re:Half an explanation (0)

Anonymous Coward | more than 2 years ago | (#37434624)

Most(all?) planet have an elliptic orbit, some of them might be "drifting too close" to the star one or two times a "year". Big planets can also make smaller planets orbit slightly more irregular.

Re:Half an explanation (1)

mark-t (151149) | more than 2 years ago | (#37447404)

My real point was that if a so-called gas giant were to have its atmosphere ripped away simply by being too close to its parent star at its perihelion, it would probably never have had the opportunity to have that atmosphere in the first place.

Of course! (2)

hesaigo999ca (786966) | more than 2 years ago | (#37434674)

Eureka moment....here is what I believe, if the clouds are like the cocoon of a moth, helping keep it safe until it transforms, then you could almost say that the cloud is there for a reason, and that the planet is now morphing into a solid planet ready for life. This would imply that the gas is great vs. anything damaging to a planet while forming....such as cosmic or gamma rays, solar winds, UV rays etc...whatever that might be ....we can also deduce that if the gas planets are the precursors to
formed planets...then we can assume there is an evolutionary path that forces the gas inside to condense while the gas outside stays there for protection...leading to believe that there are 2 types of gas...one for creation of , and one for defense....

Now that we know this, I think if we were to use that same information and look into the defense properties of that second gas, in order to define what it is made up of, and maybe replicate that someway for our development of mars, in essence helping the mars rock to become habitable (again or for the first time?) ...
it might help us create a second rock that can hold human life.

Re:Of course! (1)

Tsuki_no_Hikari (1004963) | more than 2 years ago | (#37436220)

And I would have to ask you how life would form when the rocky core is encased in a solid hydrogen shell. Not to mention once you have a gas giant close enough for its atmosphere to be stripped by its star, then you're pretty much a lost cause for developing life. Especially when the entire atmosphere has been stripped and all that is left is an airless world. This isn't like a gas giant being stripped of most of its atmosphere and leaving an Earthlike world behind.

Not to mention that cocoons were an evolved trait in insects to fulfill a need. There is no mechanism in astrophysics which acts as you believe. Gas giants form because they accreted gas and rocky material during the formation of that star system. This is not due to some cosmic evolution whose purpose is to create life on a planet.

Mars is also the way it is because it no longer has a magnetic field to protect its atmosphere from being stripped away by the sun. There is no way that we will ever be able to replenish the atmosphere, nor is there a way that the planet will be habitable for us without protection from the environment and solar radiation.

Re:Of course! (1)

hesaigo999ca (786966) | more than 2 years ago | (#37439774)

>This is not due to some cosmic evolution whose purpose is to create life on a planet.
This is based on proof or theory , as most people tend to forget that ALL space information (that has not been found to be truth) is still just theory.
If someone were to say that planets are actually alive, and that they were beings, you would say...what?
However, consider the mechanisms that planets harboring life has in order to maintain its stability, sort of like defense mechanisms if you will, then you could say that they are living, and the make up of a planet being "alive" as "we" think it, may need to change, in order for us to save the world we live on now....

We all seem to view it as a planet that needs no help in maintaining itself, yet with now 7 billion people taking away its materials, and energy, to support itself, what is left for the planet itself....the ecosystem on a global scale is as real as you going to the bathroom and forgetting to wipe continuously, after a while you will develop a rash....that is just the way it is!

Re:Of course! (1)

Tsuki_no_Hikari (1004963) | more than 2 years ago | (#37441654)

Correct, we are still learning about this field. However, you are erring in that you are treating a planet like it is a living entity rather than what it really is. The planet isn't having any trouble at all in maintaining itself due to our existence. What is having trouble maintaining itself is the complex balance or ecosystems which reside ON this planet. The fact that Earth has oceans and land and a favorable atmosphere does not in any way suggest that the planet itself is alive or predisposed toward making life possible. You are attempting to consider the entire planet to be an organism simply because it harbors an ecosystem on it, and while you believe that just because we do not have a solid model of how everything works in space, it does not open the door for any and all possibilities. What you hint at is outside the realm of scientific logic and really doesn't have a foot to stand on.

And a large amount of our models of space are currently hypotheses, not theory. In science, theory is about as good as fact.

Re:Of course! (1)

hesaigo999ca (786966) | more than 2 years ago | (#37445580)

With your said analogy of a planet, technically we would not be considered alive either....if all we are is a bunch of atoms strung together and
kept in a particular state by a beating heart some lungs to provide oxygen, and maybe a stomach to digest food to provide fuel to continue
existing, then of course the planet is not alive, we are not alive etc...

However, if you consider the fact that an animal is alive as much as a human, even though they do not share the same type of intelligence seeing as they do not have souls (we do not know for sure)....and thereby do not exist the same way we do (i don't subscribe to this myself), then technically they are as alive as we are...as I have been able to share / communicate with my dog many times where I let it be known I wanted result a to be produced, and it produced it.

So now the question becomes how do we prove if something is alive as we are....or as a living being ....remember plants have no intelligence we know of, yet they are still considered "alive"....so for all intents and purpose, because we lack a way to understand a planet as a living being, does not mean it is NOT a living being, it just means we do not know how to prove it yet.

The fetus is not alive until later, but somewhere along the line it becomes self aware....maybe planets have that too, except not in the way we would recognize it to be interpreted as being alive under our standards. They are alive further down the evolutionary chain, and maybe has a unified response system built in for certain events, such as global warming being a defense mechanism against pollution....

All I know is that we would have needed to be present during the creation of a planet all the way through its early existence to see its development in order to truly know if it was in fact alive or not....in a petri dish, it is easy to see the life cycle of a microbe or single cell organism, yet try doing that on a massive planetary scale and it becomes impossible due to our limited lifespan...

This is what happens when people "think" they know based on assumptions made through the years about things that today still are not truly tested for
fact and evidence. They never thought that there could be a brown dwarf star smaller then a planet, yet they found one....so I guess it debunks that and many other assumptions on their part....they being the scientists over the years that assumed many things...

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