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Space Science

Is Jupiter Earth's Cosmic Protector? 222

Hugh Pickens writes "Last Sunday, an object, probably a comet that nobody saw coming, plowed into Jupiter's colorful cloud tops, splashing up debris and leaving a black eye the size of the Pacific Ocean — the second time in 15 years that this had happened, after Comet Shoemaker-Levy 9 fell apart and its pieces crashed into Jupiter in 1994, leaving Earth-size marks that persisted up to a year. 'Better Jupiter than Earth,' say astronomers who think that part of what makes Earth such a nice place to live is that Jupiter acts as a gravitational shield, deflecting incoming space junk away from the inner solar system where it could do to humans what an asteroid apparently did for the dinosaurs 65 million years ago. 'If anything like that had hit the Earth it would have been curtains for us, so we can feel very happy that Jupiter is doing its vacuum-cleaner job and hoovering up all these large pieces before they come for us,' says Australian amateur astronomer Anthony Wesley, who first noticed the mark on Jupiter. But others say the warm and fuzzy image of the King of Planets as father-protector may not be entirely accurate. In 1770, Comet Lexell whizzed by the earth, missing us by a cosmic whisker after passing close to Jupiter. The comet made two passes around the Sun and in 1779 again passed very close to Jupiter, which then threw it back out of the solar system."
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Is Jupiter Earth's Cosmic Protector?

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  • by Anonymous Coward on Sunday July 26, 2009 @11:21AM (#28827171)

    It's a bit like saying one speck of dust is protecting another speck of dust from other, smaller dust, as they swirl around an eddy of warm air in a coliseum.

    • Luckily... (Score:2, Interesting)

      by denzacar ( 181829 )

      The Earth has not yet faced a galaxy coming straight at it.

      This reminds me of that anti-tiger rock I keep in my sock drawer?
      That rock is so good, damn tigers are dieing out in India. Maybe Jupiter has similar effect on galaxies?

      • You mean "dying", right? Or are the tigers getting cast and molds made of themselves?
        • Re:Luckily... (Score:4, Insightful)

          by derGoldstein ( 1494129 ) on Sunday July 26, 2009 @01:20PM (#28828065) Homepage

          There's actually no "Present Participle" for making/molding/pressing dies. The action itself is usually "pressing", "blanking", or "broaching". More information here [].

          On a side note, the Bengal tiger is quite intelligent and resourceful. I wouldn't be surprised if they did decide to go into the manufacturing business.

        • Re: (Score:2, Funny)

          In retrospect, "The tiger is cast" would have been cooler for Caesar to say before crossing the Rubicon...
          • Re: (Score:3, Funny)

            by SEWilco ( 27983 )

            In retrospect, "The tiger is cast" would have been cooler for Caesar to say before crossing the Rubicon...

            Yes, but have you ever tried to cast a tiger? Not only is picking it up awkward, but they don't really want to let go and become a flying creature. On the other hand, once the task is done you're likely to think a battle will be a relaxing activity.

        • Wanted to type "dying", typed diing, spell checker corrected to dieing, didn't preview text myself...

          It happens.
          I remember once I mistyped "Queue" as "Que", to which someone replied "Que?"... we laughed... good times.

      • Re:Luckily... (Score:4, Interesting)

        by mrsquid0 ( 1335303 ) on Sunday July 26, 2009 @01:34PM (#28828189) Homepage

        > The Earth has not yet faced a galaxy coming straight at it.

        The Earth is facing a galaxy coming straight at it. The Andromeda Galaxy is on a collision course with the Milky Way, and there is a very real possibility that the Sun will be ejected from our Galaxy when this happens. Fortunately, this is not going to happen for about three billion years

        • Re:Luckily... (Score:5, Insightful)

          by mfnickster ( 182520 ) on Sunday July 26, 2009 @02:48PM (#28828655)
          Whew! That's a relief... I thought you said three million years.
        • Re:Luckily... (Score:4, Interesting)

          by dryeo ( 100693 ) on Sunday July 26, 2009 @03:09PM (#28828825)

          Actually from what I understand, getting ejected from the galaxy would probably be the best outcome.
          There is also a chance of the Sun being put into an orbit that takes it through uninhabitable parts of the galaxy such as the core. Also when the collision happens it will trigger a very large spurt of star formation leading to more supernova and just large amounts of radiation from large new stars. Not to mention the chance of a close encounter with another star disrupting the orbits of the planets in the solar system.

        • Re: (Score:3, Interesting)

          by Fluffeh ( 1273756 )
          Isn't about three billion years when the sun is supposed to be in it's bloated red giant phase anyhow, making whether the solar system is ejected or whether we end up in some inhospitable part of the galaxy a rather moot point?

          Looking at it, seems like either outcome means lights out (well, probably more like lights on one hundred million times more powerful) but whatever happens, here is where we don't want to be.
    • Scatter! (Score:2, Insightful)

      by Anonymous Coward
      We have to get our eggs off this speck of dust.
    • by erroneus ( 253617 ) on Sunday July 26, 2009 @12:07PM (#28827537) Homepage

      No, it proves that "God" is the planet Jupiter and we were created in his image... so keep eating! To be more god-like, you must be more round, heavy and gassy.

    • Re: (Score:3, Informative)

      by FatdogHaiku ( 978357 )

      It's a bit like saying one speck of dust is protecting another speck of dust from other, smaller dust, as they swirl around an eddy of warm air in a coliseum.

      Right, if the dust is going fast enough to vaporize on impact... Hey, that might be pretty except for the UV damage to the eyes. Anyway, as someone stuck on the "protected" speck, I'll take any extra protection I can get... Sure hope our magnetic field "condom" continues to hold up against all the nasty stuff in the sunlight too...

    • IMO, this is more about Jupiter tossing regular visitors to the inner planets out of the system rather than randomly snagging non regular objects, since they tend to have eliptical orbits that often take them out past the outer planets and then back around the sun. Although it's unlikely it would hit a planet, it is likely that over thousands of passes, the gravity well from the large bodies will end up ejecting the object in a close pass due to a slingshot.
    • On whatever scale you care to mention...I think you're downplaying the significance the Earth holds for your readers!
    • Re: (Score:3, Informative)

      by JoeMerchant ( 803320 )

      It's a bit like saying one speck of dust is protecting another speck of dust from other, smaller dust, as they swirl around an eddy of warm air in a coliseum.

      The difference is that the bulk of material in the solar system lies in a plane, and while Jupiter may only cover a tiny fraction of that plane _on any given orbit_ it, and its gravity, does cover a larger radial sweep than the Earth does, so when an object makes enough passes to have a significant chance of hitting Earth, the chance of getting ejected or consumed by Jupiter is much greater.

      I'd hardly call it a 100% effective shield, but Earth's rate of bombardment may be an order of magnitude or two low

  • A New Criteria? (Score:4, Interesting)

    by eldavojohn ( 898314 ) * <(eldavojohn) (at) (> on Sunday July 26, 2009 @11:21AM (#28827179) Journal

    Is Jupiter Earth's Cosmic Protector?

    If this is true, it gives us another criteria to look for in distant solar systems that we suspect may harbor life or that we would like to colonize: a large shield planet in the same system capable of leaving the smaller world to develop uninterrupted.

    It is interesting to wonder if our odds increase or decrease on being hit when there is a large massive body in our solar system. Like the article and summary say, some objects that would not have come close could be put on course for earth via Jupiter's gravitational forces. Who knows, maybe massive bodies like Jupiter pull more space debris into our system and make it more hostile than if it were just the earth orbiting the Sun?

    • Re: (Score:3, Interesting)

      Or a bisolar system, however the radiation levels and orbits may be too chaotic in such system.

      Just to put things in perspective, Jupiter is about 9/1000 the mass of the sun. However I would point to the multitude of our gas giants. Saturn is about 2/1000 the mass of the sun, which is also significant. The other two gas giants are significantly smaller. I'd say the existence of gas giants within the carbon--water habitable zone can provide safe harbors for life as well. But I'd say a stable environment in a

    • Re: (Score:3, Informative)

      by liquiddark ( 719647 )
      This isn't a new criterion. Jupiter's role as a protector of life on Earth has been recognized for a long time. As an example of its mention,this [] article starts from the assumption that it's understood that Jupiter has a role as a protector (and then goes on to suggest that recent research may debunk that idea, but that doesn't change the original sentiment).
    • Re: (Score:2, Interesting)

      by oiron ( 697563 )

      Of course, the truth is that we're guessing out of our hats there...

      What makes you think that there could not be a life-form adapted to living in a planet/moon which gets regularly hit by various bits of artillery bombardment from space? Bacteria have proven that they can live in space. All it takes is a little weird evolution to make lifeforms that can (as a group, at least) survive such a major blow. Possibly a planet-wide organism, or at least, a planet-wide ecosystem?

      Come to think of it, we already have

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      Jupiter is like seat belts. Seat belts save lives and that is a fact. Thousands of lives are saved every year due to them but every once in a while there is the odd exception where wearing a seat belt would have killed them. Jupiter acts the same way. There may be the odd rock thrown out way because of the planet but more often than not Jupiter will throw it out of the system or eat it up.

    • Re: (Score:2, Interesting)

      It is interesting to wonder if our odds increase or decrease on being hit when there is a large massive body in our solar system. Like the article and summary say, some objects that would not have come close could be put on course for earth via Jupiter's gravitational forces. Who knows, maybe massive bodies like Jupiter pull more space debris into our system and make it more hostile than if it were just the earth orbiting the Sun?

      Understanding the effects of Jupiter's gravitational field is the main thing. How close does an object of a catastrophic mass need to be before it is A) redirected to earth, versus B) sucked in to Jupiter. I think your theory is already answered by the summary:

      Jupiter acts as a gravitational shield, deflecting incoming space junk away from the inner solar system where it could do to humans what an asteroid apparently did for the dinosaurs 65 million years ago.

      Wonderful when sentences contradict themselves. It's pretty clear that Jupiter was there 65 million years ago too. The problems include: 1) If Earth is on one side of the solar system (with the asteroid), and Jupiter on the other; probably won't h

  • Sorry for the dangling preposition in the subject, but regardless of whether or not Jupiter acts as a magnet for dangerous astral bodies, I wonder how risky it is to leave that job to Jupiter.

    We have seatbelts in cars despite the mandatory brakes which are installed. We have random personal screenings at the airport even though we have a standardized process of metal detection and baggage scanning. We should not just sit idly without a comet/asteroid detection and elimination system just because Jupiter is

    • I don't want to get caught in the slamming door. How about some information, please!

      We have reason to believe that you have fallen a victim to weapons of psychological warfare. []
      For your own good, turn of your audio and video receiving devices as well as any audio or video player and go get some sleep.

    • Why not correct your dangling preposition rather than apologize for it?

    • This is the exact reason we need thermonuclear hydrogen bombs stationed in outer space, ready to shoot: Unlike the dinosaurs, we don't have to be sitting ducks, we have the ability to defend ourselves against incoming comets. The problem with stationing bombs in outer space is an issue of trust: people down here still haven't figured out how to live in peace and leave each other alone, the UN is still not a functioning body of world government, people still play the "I don't trust you, I'll kill you before
      • Re: (Score:3, Interesting)

        by hedwards ( 940851 )
        We don't do that because the likelihood of somebody abusing the weapons to kill us is substantially higher than the risk of being killed by an impact. Further more you're assuming that we'd get it right, and let's face it we tend to be kind of hit or miss on things like that. We were able to more or less successfully fight the ozone layer problem, but pretty much completely refuse to do anything about global climate change.

        I'm not sure what makes you so sure that there'll be much left by the time a space
        • (Pyongyang, NK) A defiant North Korea announced the launch of a projectile the size of several soccer fields (football fields in the U.S.) that struck Jupiter today. As it descended into Jupiter's cloud tops it was transmitting data and broadcasting the "Song of General Kim Il-sung" and "Song of General Kim Jong-Il", about Kim Jong-Il and his father.

          North Korea's neighbors condemned the launch as "unfortunate". The U.S. State Department declined to comment, although in another display of his ability to mi
  • by blahplusplus ( 757119 ) on Sunday July 26, 2009 @11:24AM (#28827195)

    ... is the fact that eventually we have to get off earth and learn how to survive in the hostile universe anyway.

    • The current STS-127/Expedition 20 mission has shown us that troubleshooting a malfunctioning urine-recycling toilet and a tripped circuit breaker on a carbon scrubbing unit are far easier to fix in LEO than out father, especially considering how critical both systems are to a more distant mission.
    • by Kjella ( 173770 ) on Sunday July 26, 2009 @05:03PM (#28829941) Homepage

      ... is the fact that eventually we have to get off earth and learn how to survive in the hostile universe anyway.

      With all due respect, as much as I want mankind to go into space there's nothing to suggest earth will become uninhabitable in the next few million years. Not unless we destroy it, but in that case there's not much hope we'll be capable of interstellar travel either. On that angle, who cares if that happens this century or this millennium? We could easily have spent another million years on the ape stadium, shaving off a few centuries means nothing.

      The odds that any interstellar "manned" spacecraft would be anything like today's manned mission is highly unlikely. More likely what we're doing now is like testing the extreme conditions of cross-continent horse-and-buggy rides when the solution is a jet plane. I'm guessing we'll send something like space probes that'll thaw or build embryos on site with nursing robots to form new colonies, sending fully grown people is just insanely inefficient in so many ways.

      You may think that's inhumane, but I think it's the only humane thing. Imagine being second generation plus on a ship in the dark void of space, only seeing pictures and videos of earth while you're trapped on a tin can because your ancenstors decided to make you a pawn in colonizing a new planet. Plus, then they'd also be real people that quite possibly, or even probably, will die at some point from ship failure. A probe on the other hand may only produce humans if all flags are green.

      • Re: (Score:3, Informative)

        I think you're missing the benefit of people going into space:

        Really smart people the best of humanity no longer have to answer to the politics of the earth and therefore can have new moralities based on secular science that don't have to cow to the stupids, a civilization on another planet is not within reach of the crazy fundies here on earth.

        When the earth was less populated it was possible to create new traditions and moralities by moving away and setting up your own shop, now imagine you can do that in

    • I was actually wondering exactly how far from ignition Jupiter is right now. If it keeps absorbing masses like this, it could ignite, then we would have a lovely binary system. We'd only be one sun away from Tattoine.

  • by Anonymous Coward

    Now if Jupiter were like my boss, it would fling those comets at the earth with the message: "This issue is escalating rapidly. I need you to work on this today; send me status before you leave."

  • by 3seas ( 184403 ) on Sunday July 26, 2009 @11:29AM (#28827229) Homepage Journal

    That Jupiter really sucks?

  • Greater benefic (Score:5, Interesting)

    by MadLad ( 1331393 ) on Sunday July 26, 2009 @11:36AM (#28827273)
    In astrology, Jupiter is considered the "greater benefic," the planet that bestows fortune, luck, and positive benefits.

    Just sayin'.
  • The end is nigh (Score:5, Insightful)

    by bitemykarma ( 1515895 ) on Sunday July 26, 2009 @11:38AM (#28827291)

    The Earth will eventually be wiped out, obviously. We can't get lucky forever.

    We'd better spread outselves out.

  • by spleen_blender ( 949762 ) on Sunday July 26, 2009 @11:43AM (#28827329)
    Is it actually more likely for a body to be directed away from Earth than to Earth by Jupiter? I mean, it seems that a body not destined for Earth could otherwise hit if affected by Jupiter's gravity sufficiently.
    • The proportion of objects which follow this relationship is almost by definition no greater than that which would have hit Earth but for Jupiter's influence, unless there's some cosmic pinballer out there who is specifically banking shots off of Jupiter to try to hit the Earth specifically. Jupiter is gigantic. Just by looking at the"shadow" created by its bulk, not counting the additional deflection from gravity, it creates a zone 22 earth radii wide where nothing coming into the solar system will pass.
      • Re: (Score:3, Insightful)

        by John Hasler ( 414242 )

        The circumference of Jupiter's orbit is about 760000 Earth radii so Jupiter is "shielding" about .000029 of its orbit, and that's assuming everything comes in exactly in the plane of Jupiter's orbit. It doesn't.

        • What's your suggestion? That the number of objects deflected into the earth is higher than those swept up + those deflected away? That's what I was responding to. Yes, Jupiter's effect is probably not that high, but all the same it's high enough, particularly assuming that most dangerous objects are trapped in a stellar orbit rather than simply shot like a cannon at the earth. The probability that Jupiter has a clearing-house effect on bodies in orbit turns out to be pretty high over the course of billi
  • by DynaSoar ( 714234 ) on Sunday July 26, 2009 @11:45AM (#28827359) Journal

    Jupiter is the only planet in our system close enough to the sun and with a deep enough gravity well for them to have a barycenter (common orbital center) outside the sun's surface. That sort of wobbly orbital mechanics has far more effect on trajectories of small bodies than a nice, neat set of concentric circular orbits. The sun-Jupiter system will be more likely to cause fluctuations that result in small interlopers to get thrown out of the system or sucked into one of their gravity wells. Seeing the result on Jupiter is rare. Seeing it at the sun is more common. Between the two they're going to suck up far more than hit elsewhere.

    But their influence is only the majority of a chaotic multi-body system. Just because they account for the most hits doesn't mean they take them all and nothing gets through elsewhere. Of course some will miss the big guys and hit (or nearly so) some of the others. That's the nature of a chaotic system of orbital mechanics. They are not exerting influence in an intentional manner, rather a deterministic but fairly unpredictable manner.

    To assume a certain thing always happens because it has happened, and also to say it not accurate because there is an exception, is the sort of low caliber absolutist thinking that's common in "modern" science reporting. I have no doubt the parties credited with these viewpoints understand quite well the situation, and the apparent controversy is a function of the author of TFA.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      The author of TFS obviously didn't claim that Jupiter takes them all since he mentioned the dinosaur extinction. Since your post is devoted to attacking something that wasn't said, we can safely ignore it. Thanks.

    • by Yvanhoe ( 564877 )
      Earth has a magnetic shield. Earth has a gravtational shield. Whil I agree that all of these are completely natural, they both strike me as a improbable and essential to mankind. Discovering such things makes us realize that Earth is an exceptionnal place, and lowers the result of the Drake equation by a few orders of magnitude. If it takes such coincidences for life to develop, then life may be rarer in the universe than we first thought.
  • Amazing (Score:5, Interesting)

    by Corson ( 746347 ) on Sunday July 26, 2009 @12:00PM (#28827475)
    I find it amazing and worrisome that an object that size can get so close to Earth and hit Jupiter without astronomers learning about it until after the fact. To me, it is an indication that current near-earth object surveillance systems are not worth much.
    • Re:Amazing (Score:5, Insightful)

      by ceoyoyo ( 59147 ) on Sunday July 26, 2009 @12:17PM (#28827623)

      Jupiter isn't exactly "near-earth," and doesn't count as "close to Earth" when you're talking about asteroids and comets hitting or almost hitting planets.

    • Re: (Score:3, Interesting)

      Except that the object isn't that massive. To create a hole the size of the Pacific Ocean in Jupiter wouldn't require a very large object at all--try flicking a pebble into a cloud created by a fog machine.

    • Re: (Score:3, Insightful)

      Well, perhaps (and this is just a guess, mind you), astronomers didn't have equipment quite as advanced as current near-earth object surveillance systems back in 1770 when the incident occured.
    • Jupiter is not in near-Earth space. There is not a lot of effort being put onto looking for small objects at the distance of Jupiter. This is because the distance makes them very hard to find, and a lot of effort is being put into finding objects that are on Earth-crossing orbits.

    • Maybe they couldn't see it because there was a big ass gas planet in their line of sight.
  • If the word logically doesn't offend you in that context. The largest temple in Rome was that of Jupiter Optimus Maximus on the Capitoline Hill (Wiki). So the Romans at least worshiped deities of some real world benefit.

  • by Jeremy Erwin ( 2054 ) on Sunday July 26, 2009 @12:16PM (#28827611) Journal

    Jonti Horner and BW Jones [] have written a series of papers on this, summarized in this Astronomy and Geophysics article [] The first paper deals with the Asteroids []. The second, in press, considers the Centaurs [] The third, of perhaps most relevance to this discussion, considers the Oort Cloud objects.

    (To simplify the simulations, Earth was inflated to one million times its actual size. A juicy target indeed)

  • by pdhenry ( 671887 ) on Sunday July 26, 2009 @12:26PM (#28827697)
    The whole notion that some body that is on the other side of the sun from us half the time is protecting us doesn't really work in my mind. It seems that it only works if you imagine the universe is laid out on a line. Put the Sun at zero, the Earth at 3 and Jupiter at 10 and then anything heading your way from >11 has to get past Jupiter first. In reality we can't even rely on foreign objects coming in along the ecliptic.
    • Some objects that would have hit earth will hit Jupiter instead, obviously not all since the Earth and the Moon have been hit a lot. Hence Jupiter protected the Earth from those particular objects. Hence Jupiter is protecting us.

    • Space-time is curved by gravity. It's not important where Jupiter is in its orbit. Objects passing through the Solar System are attracted TOWARDS it.

      Your simplistic example assumes objects are moving in flat space, and they are not.

  • the earth has had several mass extinctions in the past, the most recent was 65.5 million years ago when it is believed a meteor impacted the earth causing the demise of the dinosaurs, there

    there was a few others that may or may not been caused by cosmic impacts
  • 'Better Jupiter than Earth,' say astronomers

    I think I speak for all of us Jupiterian slashdotters when I say I have a problem with that statement.

    • Speaking for the Jovian High Council, the representatives of the real inhabitants of Jupiter, I can say you truly don't know what you're talking about.
  • The whole "Jupiter shield" idea is myth. There's no reason to assume that Jupiter will throw more junk into wider orbits than into tighter ones more likely to hit the earth.

  • What about when we're between Jupiter and the sun? Then the pull from each would put us pretty much square in the path of whatever's coming, wouldn't it? No wonder people are so scared of syzygies.
  • by rlseaman ( 1420667 ) on Sunday July 26, 2009 @04:17PM (#28829421)

    The point is that not only does Jupiter protect the terrestrial planets now, but that Jupiter has protected Earth from the birth of the solar system. This is one reason that Earth isn't yet another gas giant.

    The recent controversial redefinition of the word "planet" ( []) discusses this "vacuum cleaner" effect as the third of three criteria:

    1. orbits the Sun
    2. mass enough to be spherical
    3. has "cleared the neighbourhood" around its orbit

    Jupiter is by far the largest planet and has by far the largest such effect. A lot of the reasoning in the comments has caused one to question how well Astro 100 courses are being taught, but perhaps it is ok to venture one simple statement for why Jupiter preferentially protects the inner solar system. The comets that threaten us originate in the distant Oort Cloud ( []). They visit the inner solar system, but their orbits all begin far outside. It is thought that external perturbations play a role in causing them to plunge inwards. Jupiter (to oversimplify outrageously) stands between us and the bombardment.

    Fundamentally this is the famous "three body problem". The equations describing Newtonian gravity are straightforward to solve for two bodies, and impossible to solve precisely for three or more. Relativistic corrections add a bit of spice. As a result planetary mechanics requires numerical integration.

    The solar system is full of neat resonances and points of stability such as the Lagrangian points. Jupiter's Trojan asteroids ( []) cluster at L4 and L5 and are thought to be as numerous as those in the main belt. Our Moon's tidal locking is a) imperfect (since the orbit is rapidly growing ( []), and b) simple compared to resonances ( []) between other bodies.

  • Jupiter clears out a path of asteroids and comets by being so massive that it attracts them to itself to either fling it to an orbit in the asteroid belt or out to the Oort Cloud or takes a hit from it to prevent it from cluttering up the solar system.

    If it wasn't for Jupiter and other gas giants, we'd have more comets and asteroids getting near the inner planets, so Saturn, Uranus, and Neptune are Soccer Goalies as well.

    But they don't always stop everything, just a majority of it.

    Early on when our solar sy

  • Jupiter's core (Score:3, Interesting)

    by Tubal-Cain ( 1289912 ) on Sunday July 26, 2009 @06:00PM (#28830453) Journal

    Last Sunday, an object, probably a comet that nobody saw coming, plowed into Jupiter

    First, I'd like to apologize for being slightly off-topic.
    I wonder why pretty much all astronomy sources are unwilling to state with certainty that Jupiter has a rocky core. It's only natural that more solid material has fallen into the atmosphere than has been captured in orbit. It's not like the comets and meteorites will 'orbit' for very long within friction of the atmosphere, so the only place for solid matter to go is the center.

    • Re: (Score:3, Interesting)

      by Xyrus ( 755017 )

      The heat and pressures are so intense at the center of Jupiter there's really no way to say definitively what's there. It may be a spongy form of matter (semi-metallic hydrogen). It could be super-heated slurry of materials like our core. Or it could be a solid heated sphere of materials.

      It depends on what the core is made of, the densities of the materials, the convection, etc. . That's a lot of unknowns to deal with to make the assumption that it has some sort of rocky core.

      The point being, we're still ge

"I shall expect a chemical cure for psychopathic behavior by 10 A.M. tomorrow, or I'll have your guts for spaghetti." -- a comic panel by Cotham