can i simply say that the earth's core is a ball of fire?
553094
I would believe that analogy to be inaccurate.  The inner core is more of a very dense, solid mass of mostly iron and with its spin, among other things, gives our Earth its magnetic field.  The outer core, while quite hot, I would not call it a ball of fire.  It is more in the state of fluid, plastic like state which churns and, and at its boundary, mixes with the mantle to some degree.  Our planets core is dense and hot, but not a ball of fire.
631787
The number is less than the mass of the Earth's mantle divided by the average mass of a sand particle. According to http://www.astro.wisc.edu/~ewilcots/astro236/drakeandrichter.pdf, the mass of the Earth's mantle is around 1.4*10^24 grams. According to http://www.ma.iup.edu/~hedonley/drag/drag25.html the mass of a sand particle is around 1.7*10^(-7) grams.\nThus the amount of particles in a mantle made up completely of sand would be around (1.4/1.7)*10^31 = 8.2*10^30. In America, this would be called 8.2 nonillions by the nomenclature-obsessed minority. Since the mantle is not made completely up of sand particles, the number of sand particles is less than this number, and since that number is less than infinity, so is the number of sand particles. It is thus an unknown, but finite, number.\n\nPS: Note that a "zillion" is not a real number. It is a fictitious play on the way we name large numbers and does not correspond to any exact amount. See http://www.google.com/search?hs=Xwl&hl=en&lr=&safe=off&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=define%3Azillion&btnG=Search .
594566
The part you are talking about is a conversation where God was asking Job where were you when I created the earth?\n\nDoes Job 28:5 refer to the apparent molten state of earth’s interior when it says: “As for the earth, out of it food goes forth; but underneath it, it has been upturned as if by fire”?\n\nNo. The context reveals that this pertains to man’s efforts to find earth’s treasures. (Job 28:1-4) Aboveground the farmer peacefully prepares the soil, sows seed and cares for the growing grain. Thus the earth produces food. Underneath earth’s surface, however, man carries on a turbulent ‘upturning’ activity, with effects comparable to that of a ravaging fire. Miners gouge and wrest from earth’s bosom precious stones and metals.\n\nIt may be noted that a number of translations render Job 28:5 somewhat differently. For example, the Authorized Version reads: “As for the earth, out of it cometh bread: and under it is turned up as it were fire.” Based on this rendering, some commentators suggest that the fire refers to the glow of precious stones and metals that are uncovered by man.  Understanding the “fire” to allude to man’s mining operations fits the context better and agrees with the renderings of many modern translations.
612104
The explanations of fire in most standard reference works, not to put too fine a point on it, suck. The Encyclopaedia Britannica, for example, takes the following ineffectual stab: "rapid burning of combustible material with the evolution of heat and usually accompanied by flame." No wonder people have lost faith in science. Time to let a professional show how it's done. We'll start by reviewing the defects of the EB definition.\n\n(1) Rapid burning. OK, fire burns rapidly. Slow combustion, also known as oxidation, includes such nonfiery processes as rusting and digestion. However, to say that fire involves burning is to embark on a circular definition: What is fire? When something burns. What is burning? When something is on fire. We need to address the matter in more basic terms.\n\n(2) Combustible materials. Redundant. If a material is capable of rapid burning, by definition it's combustible. Also, "materials" is needlessly vague. One specific material, oxygen, is always involved.\n\n(3) Evolution of heat. I don't know what this is supposed to mean either.\n\n(4) Usually accompanied by flame. "Usually accompanied by" my arse. Flame is the quintessential pyrolytic phenomenon, not a mere by-product.\n\nNow for a proper definition, devised by myself: "Fire is the rapid combination of oxygen with fuel in the presence of heat, typically characterized by flame, a body of incandescent gas that contains and sustains the reaction and emits light and heat." Let's go through this bit by bit:\n\n(1) Rapid combination of oxygen with fuel in the presence of heat. Oxygen, fuel, and heat are the essential ingredients of fire. \n\n(2) Typically characterized by flame. The pup qualifier "typically" allows me to sidestep the issue of apparently nonflaming fires, like you get with burning charcoal. I suspect charcoal fires do create flame--you just can't see it due to the lack of impurities or incompletely burned fuel in the plume. (You can't see a fuel fire at an Indy or CART race either, because the cars run on clean-burning methanol.) But that's a matter we can leave for another day.\n\n(3) Body of incandescent gas. Flame defined. Most encyclopedia and dictionary definitions blow past this entirely, allowing persons such as yourself to imagine that fire is "pure energy" or similar nonsense. We say "body" because the gas has a characteristic structure and composition. We say "incandescent" because (a) it sounds scientific, (b) it means "luminous with intense heat," precisely what we are attempting to convey, and (c) if the Teeming Millions are going to learn one vocabulary word today, by God "incandescent" should be it.\n\n(4) Contains and sustains the reaction. Flame isn't just the result of fire; it is the fire. What's more, without the flame's heat the fire would go out.\n\n(5) Emits light and heat. Duh. However, we mustn't overlook the obvious.  \n\n>>>why do things that are put in it come out totally destroyed?\n\nOf course most things that go into fire aren’t totally destroyed. Most metals, glass, ceramic and so forth all emerge unscathed from fire. Even wood and paper aren’t totally destroyed, they leave an ash and charcoal residue as well as fine particles that we can see as soot and smoke.\n\nFire will ‘destroy’ anything organic that can be completely oxidised at the temperature that it burns at, but that is simply because the oxidation process converts the organic material to carbon dioxide,  and water. IOW the material isn’t destroyed it is just converted to gas and that gas blows away.\n\n>>>>>what fuel does it need from say, paper,\n\nThe paper IS the fuel the fire needs. The fire converts the paper into gases and ash. Or more accurately fire is the process of converting paper into gases and ash.
540447
Let's just talk about Earth. The earth's diameter is 12756 km. Its circumference is pi x 12756 = 40074 km. The earth spins 1 round in 24 hours. That's 1700 km/h, or 472 m/s. If it rotates in an OPPOSITE direction, it's like the Earth is rotating at 944 km/s and suddenly stops. What happens? You fly through the air at 944 km/s. All the houses fly through the air at 944 km/s. Whole forests fly at 944 km/s. Even whole mountain ranges and mountain tips fly at 944 km/s. The ocean's waters fly backward at 944 km/s. Talk about a uber tsunami. I don't know what the friction of air against these object would do to them. Can anyone solve that? Even the Earth's crust might become detached with its outer mantle, I think. Lava breaks out everywhere, global earthquakes... In short: All hell breaks loose. Man, that's even worse than the Death Star. Superman actually does that to Earth in one of his movies. He's a major nut!
529191
Sure.  Anything shaped like a sphere or ball is an orb.
934445
A molten core of super heated metal (believed to be Iron and Nickel) is spinning at the center of the earth faster than the exterior of the earth is rotating.\n\nCharged Particles create a magnetic field when they move.
431316
earth is like a boiled egg. The yellow one is the core, the white one is the mantle, the thin layer between the shell and the while is the Moho and the shell itself is like the crust. Magma is molten rocks due to extreme heat and pressure. But the core is divided into two  the liquid outer core and the solid inner core. Core is not a rock. And also rock is the aggregates of minerals.
46639
YES, and this is so cool check it out!\nhttp://static.howstuffworks.com/gif/space-station-flame.jpg\nIt burns in a perfect sphere!
231903
In general, I agree with nacho track. There is more to it though. There is a huge mass of material in the core of the earth. A small portion of that is undergoing radioactive decay and creates heat which has to go to a colder place, as heat moves from places of greater heat to those of lesser heat as part of entropy,such as the surface of the earth. The magmas are heated by this decay and as they work their way to the surface of the earth, the pressure of rock and soil over them is lessened and the magma goes from a slightly plastic material to more or less a liquid.\n\nThe plates that underlie the crust of the earth are kept in motion because the heats does not escape evenly. There are places where continental plates are thicker and places where they are thinner.\n\nIf you ever made fudge candy, you will have observed pieces of crustier materials floating on a bed of liquid. They do move and create fissures and breaks and move slowly. Of course, if you are a good candy maker, you will stir the pot and spread the heat around so that the entire batch has reached the same degree of cooking. Earth is not stirred but just sits there like a big pot of fudge.
179806
At the center of the earth the effects of the increasing pressure (which will cause the ball to implode) are greater than the effects of the increasing temperature (which would make the gases inside the ball expand to such an extent that the ball would explode) so the ball would implode. Studies of the seismic waves from earthquakes travelling through the earth tell us that the very center of the earth's core is actually solid, the hot material crushed into a solid form by the pressure. The outer layers of the core are liquid due to the high temperatures at lower pressure.
450478
We live on a very interesting planet. This planet actually hasn't completely cooled down yet and there is a lot of activity hundreds of miles below the Earth's crust (ther crust is where we are). The center of the Earth is very very very hot and a lot of substances (a lot of it being Iron (Fe) )are in molten form down there......Have you ever seen a volcano errupt (on a documentary or in a film?)? Well that stuff coming out is Molten Lava and is a mixture of substances (mostly rock) in liquid form. You cant get too close or you'll burn from the heat. I would go on telling you about this but then we'll be talking about another subject.\n\nThe gravitational pull of the Earth is because of its mass AND because of its rotation around the sun and itself. All bodies in the universe have a gravitational force and this force effects every other "body" in the universe (a bit like a draw in a tug-o-war) (This also explains why matter never can be completely annihilated and other aspects like the existence of dark matter and so forth....but that's advanced Astro-physics) \nThis gravitational pull is measured in NEWTONS (Newton is the guy that laid down the laws of gravity after an apple fell on his head.....) You'd weigh differently on each planet due to its MASS. For example if you where to lift a matchbox on Jupiter you would need a lot of help because it would weigh a lot more then it does here.....and so would you. So much so that your skeleton would not be able to support you and you would probably crumple into a meat heap......(i'm not going into detail because this will just go on and on to knew subjects.....you can find this info on the internet.....it's more fun to find out for yourself)\n\nI hope I've been helpful.......
1038202
Because your question is specifically about gravity, I will ignore the temperature of the core. The thing that is important to realize is that gravity is an attractive force. Although it's a bit complicated, we can answer your question by considering gravity an attraction between two atoms.\n\nThe Earth pulls us down as if there were a large gravitational pull coming from the center of the planet, but this is not actually the case. The pull is actually coming from each atom of the Earth independently. It's like if you had two friends who each had a rope attached to your belt buckle. If both are standing in front of you and pull hard, you'll feel a pull that is twice as hard as each alone. If one is standing a bit to the right and the other is standing a bit to the left, and they both pull towards themselves (and they pull just as hard as each other), you will be pulled straight forward.\n\nIn the center of the Earth, it would be like you had lots of friends each with a rope attached to your belt buckle, and they were standing all around you in a circle. If they all pull, they will all cancel each other out -- you won't move at all! You wouldn't even feel it.\n\nSo, to answer your question, in the center of the Earth you would feel pretty much the same as if you were in space -- weightless.
538777
Many of us would like to live our live and find out what our purpose is, so it would be rather selfish to KABOOM the the earth. It is the internal Satan we must fight. I believe that the core of the earth is fire for the sake of keeping the oceans stable. I do not believe that he is down there,.. only in a portion of our heart. We have to find solutions to extinguish the devil there.
771006
It gets hotter, expands, and thins.  Eventually the radiation gets past it.  \n\nIf there is enough buildup of radiation from the core, you can have explosive effects.
509040
The Earth is not Hollow. Below the 60 Km crust is the semi-liquid Mantle. The core at the center is Solid.
1173782
Even though I like Oz's answer, it is actually the flow of magma in the Earth's mantle on average about 30 miles below the surface, where molten rock flows from high to low, nearing the earth's outer core where the temprature reaches to near 10000 degrees F.  Another heating element (or actually energy element, that has a side effect of heating) is radioactive decay.  Though most of the Earth's heat energy is released throught the much thinner parts of the crust that makes up the ocean floors.