Quentin Williams, associate professor of earth sciences at the University of California at Santa Cruz offers this explanation:
There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.
It takes a rather long time for heat to move out of the earth. This occurs through both "convective" transport of heat within the earth's liquid outer core and solid mantle and slower "conductive" transport of heat through nonconvecting boundary layers, such as the earth's plates at the surface. As a result, much of the planet's primordial heat, from when the earth first accreted and developed its core, has been retained.
The amount of heat that can arise through simple accretionary processes, bringing small bodies together to form the proto-earth, is large: on the order of 10,000 kelvins (about 18,000 degrees Farhenheit). The crucial issue is how much of that energy was deposited into the growing earth and how much was reradiated into space. Indeed, the currently accepted idea for how the moon was formed involves the impact or accretion of a Mars-size object with or by the proto-earth. When two objects of this size collide, large amounts of heat are generated, of which quite a lot is retained. This single episode could have largely melted the outermost several thousand kilometers of the planet.
Additionally, descent of the dense iron-rich material that makes up the core of the planet to the center would produce heating on the order of 2,000 kelvins (about 3,000 degrees F). The magnitude of the third main source of heat--radioactive heating--is uncertain. The precise abundances of radioactive elements (primarily potassium, uranium and thorium) are is poorly known in the deep earth.
In sum, there was no shortage of heat in the early earth, and the planet's inability to cool off quickly results in the continued high temperatures of the Earth's interior. In effect, not only do the earth's plates act as a blanket on the interior, but not even convective heat transport in the solid mantle provides a particularly efficient mechanism for heat loss. The planet does lose some heat through the processes that drive plate tectonics, especially at mid-ocean ridges. For comparison, smaller bodies such as Mars and the Moon show little evidence for recent tectonic activity or volcanism.
We derive our primary estimate of the temperature of the deep earth from the melting behavior of iron at ultrahigh pressures. We know that the earth's core depths from 2,886 kilometers to the center at 6,371 kilometers (1,794 to 3,960 miles), is predominantly iron, with some contaminants. How? The speed of sound through the core (as measured from the velocity at which seismic waves travel across it) and the density of the core are quite similar to those seen in of iron at high pressures and temperatures, as measured in the laboratory. Iron is the only element that closely matches the seismic properties of the earth's core and is also sufficiently abundant present in sufficient abundance in the universe to make up the approximately 35 percent of the mass of the planet present in the core.
The earth's core is divided into two separate regions: the liquid outer core and the solid inner core, with the transition between the two lying at a depth of 5,156 kilometers (3,204 miles). Therefore, If we can measure the melting temperature of iron at the extreme pressure of the boundary between the inner and outer cores, then this lab temperature should reasonably closely approximate the real temperature at this liquid-solid interface. Scientists in mineral physics laboratories use lasers and high-pressure devices called diamond-anvil cells to re-create these hellish pressures and temperatures as closely as possible.
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Reply | Report Abuse | Link to thistnx
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it's very amazing .
Reply | Report Abuse | Link to thisbut if there is molten iron in the core, how could it support the outer pressure on it.
Reply | Report Abuse | Link to thisHow much heating of the crust and mantle is caused by the tidal stresses imposed by the sun and moon?
Reply | Report Abuse | Link to thisThe extreme pressure on the inner core is what keeps it a solid. The outer core is molten but the inner core is not...molecules at that pressure are not allowed to move, hence keeping the inner core in a solid state.
Reply | Report Abuse | Link to thisThe extreme pressure on the inner core is what keeps it a solid. The outer core is molten but the inner core is not...molecules at that pressure are not allowed to move, hence keeping the inner core in a solid state.
Reply | Report Abuse | Link to thisIf we put out a fire by spreading earth on it to deprive it of oxygen - how does the core stay hot without oxygen?
Reply | Report Abuse | Link to thisPlease read my theory of gravitoethertons published in year 2002 and balloon inside balloon theory. I said that gravitoethertons produced at the common spherical boundary of matter and antimatter universe is flowing as ether in our universe and earths core is getting focussed energy to keep it hot and molten and due to flow of electron loops we get huge current flow to produce magnetism as per Farradays law.
Reply | Report Abuse | Link to thisI put forward the idea that the earths core is getting hotter causing carbon to be released from sandstone and is responsible for global warming.Whats causing the core to heat is small factors on a grand scale (ie. the moon is pulling away from earth at approx. 1 inch per year but that is adding extra pull and enormous friction on the core adding to this is the alignment of the planets and their extra gravity. Miniscule events adding up to intense pulling and resulting friction causing increased viscosity under the tectonic plates leading to increased seismic activity .Your thoughts please
Reply | Report Abuse | Link to thisWhat is wrong with using correct grammar, punctuation and sentence structure? This article is truly abysmal.
Reply | Report Abuse | Link to thisI guess we should build an giant air washing mashine ,that works with water ,it must be build near iceland ,tecnology similar to homes aspirators based in twirl water. later freeze the water near poles with giants coolers sistems.it will cool the core. long life to Jesus Crist .he lives with us.
Reply | Report Abuse | Link to thistime 13 :44
I do not believe any of the three theories postulated is correct. Radioactive decay is the theory still taught in college Geology courses. And it is the most ludicrous of all...there is almost no energy given per decay...look at the energy released every minute from active volcanoes... There hasn't been this much radioactive decay energy in thousands of years in the earth's core.
Reply | Report Abuse | Link to thisThe earth is hot at it's core because it rotates. The gravity of the sun kneads the earth's core, causing the core to heat. Look at planetary geology. Mercury doesn't have volcanoes. Why? Because it does not rotate! Venus does. Why? Because it does rotate. Mars has volcanoes. Because it rotates. etc. etc.
Look at Io and Europa...we know Io is volcanic from visual observation. We also know that Io rotates, and is affected by the gravity of Jupiter. We know that Europa rotates, and can surmise that there is a possibility of liquid water underneath the surface of ice, due to the probability of volcanic activity. Our own moon has no volcanic activity - because it does not rotate. Gravity is a weak force - but a very persistent and powerful one...
You state that you estimate , believe, don't know with certainty or precision...so this is your best educated guess. Yes?
Reply | Report Abuse | Link to thisGrammar is important but the negativity isn't needed.
Reply | Report Abuse | Link to thisI´m not a scientist. There is something I don´t understand. Maybe it is a silly question, but I understand that the earth´s crust is 3 km thick at the bottom of the sea and 70 km in Andes or Himalaya, while the mantle is 2.890 km of lava and the outer core has another 2.270 km. The total radius of earth maybe is around 6.371 km. If the temperature at the base of Earth's mantle is 3,500 to 5,500 kelvin ¿How can this 1% shell isolate all this heat? If I reduce earth to the size of a ball or better if I grow enough to have the earth in the palm of my hand (to avoid not homogenous transformation functions) ¿Should I feel it hot? or ¿Should I feel it at the same temperature I feel it now under my feet?
Reply | Report Abuse | Link to thisAbout this topic, there is always the question of why the core of the Earth is too hot, and the most recurrent theories are about the original heat created by the formation of the planet and the radioactivity decay. Neither of them explains why Mars had already cooled eons ago, if Mars is very similar to Earth, and comes from the same process.
Reply | Report Abuse | Link to thisWhy nobody is considering the influence of the Moon tides as a possible cause of the heat of the Earth?, it has to have a very considerable impact. Because of the tides the Earth loses on second of rotational speed every 18 months, and it had been happening for eons, and that enormous amount of energy, has to go somewhere.
As far as I can see it, the moon tides have to be, not only one factor of the heating of the core of the earth, but the main cause, and it explains why Mars, had been cooled far time ago and Earth hadn’t.
Maybe, it is true, that once Mars harbored life, and an atmosphere, and oceans. But the core of Mars cooled, the magnetic field collapsed and the cosmic rays swept away the atmosphere, the water and the life, and that what will happen to Earth if someday it cools. I really like this new theory which says that’s possible that life on Earth really started on Mars, explaining that Mars, was viable for life, when Earth was struggling with the process that formed the Moon, that life, haven’t had the time to evolve on Earth only.
Everybody tends to say that the energy of the Earth is unlimited, free, renewable, clean, and it is the entire contrary, the energy of the Earth is the less renewable of all types of energy, it is very precious and needed for existence of life, it is formed by comical processes beyond our capacity, and accumulated by our planet, like in a huge battery, and there is no way humanity can replace it or live without it once is gone.
The day humanity starts to drain the energy of the Earth at the same rate it does with the oil, thinking that it is unlimited, as once though about oil, it will be cause a catastrophe. Thinking this way I already think we are taking too much of this, so called, unlimited source of energy, the so called energy of the future.
my idea is different.in my opinion earth doesnt produce its own heat but it has the matter to keep the heat in most middle of the earth.heat is from the sun.if we can block the sun radiation for a little bit long,the only hot matter on earth will just be the political issue.thanks god the earth is round.why the moon is not too hot but it is also round...because its composition is different from earth,and there is no politics out there.my theory is mostly round object absorbs energy than any other object figure especially when they are active and moving.i hope my planned project will be materialised(energy is too expensive).
Reply | Report Abuse | Link to thismy idea is different.in my opinion earth doesnt produce its own heat but it has the matter to keep the heat in most middle of the earth.heat is from the sun.if we can block the sun radiation for a little bit long,the only hot matter on earth will just be the political issue.thanks god the earth is round.why the moon is not too hot but it is also round...because its composition is different from earth,and there is no politics out there.my theory is mostly round object absorbs energy than any other object figure especially when they are active and moving.i hope my planned project will be materialised(energy is too expensive)...zg the mechanic
Reply | Report Abuse | Link to thisscience is made from a piece of paper but nature is made up of words and sense.filipino boy.
Reply | Report Abuse | Link to thisA sloppy error - "The amount of heat that can arise through simple accretionary processes, bringing small bodies together to form the proto-earth, is large: on the order of 10,000 kelvins (about 18,000 degrees Farhenheit)." The "amount of heat" and the temperature are two different things altogether. Such a basic error raises doubt as to the validity of the entire article.
Reply | Report Abuse | Link to thisThere is a consistent principle of physics causing the earth's center to generate the energy we see in the form of heat.
Reply | Report Abuse | Link to thisI don't buy the left overs theory. If this is true the earth's crust is one heck of a thermos. Considering the modernist view that the earth is 4 to 5 billion years old. My coffee cools in a few minutes in ceramic.
Heat is caused by energy. It's either generated at the core or transferred into the core.
I would say transferred by motion caused by gravity. Maybe gravity itself which would translate into pressure which creates compression like a pathway towards a black hole.
Or its some type of nuclear reactor like the sun itself only compartmentalized by the outer layers of the earth.
Or combine the two concepts gravity causes a type a fission at a certain density.
Its not a concentration of iron collected at the core. Its the elements whatever they may be that are being created at the core by the tremendous pressure of the earth's mass.
Well there is some food for thought.
Bob
it could support it if it was so cause just like water supports a ship in the liquid ocean and does not let it sink simply because it is heavier. Anyway this article is nothing but scientific misinformation and lies.
Reply | Report Abuse | Link to thisIt is rediculous to claim that earth had not enough time to cool although it floats in the extremely cold colder than ice space vacum for more than 3 billion years after it's creation. Ever wondered why in space photos of planets or the moon through telescopes or exploration sattelites in orbit arround them or still images from their surfaces taken from landing devices or austronafts we see no stars at all when we see plenty of stars in images taken from the earth although earth has thich atmoshpere?
Ever wondered why while everything else moves in curves due to forces, scientists claim light travels in straight line?
NASA is keeping secrets from us
It is rediculous to claim that earth had not enough time to cool although it floats in the extremely cold colder than ice space vacum for more than 3 billion years after it's creation. Ever wondered why in space photos of planets or the moon through telescopes or exploration sattelites in orbit arround them or still images from their surfaces taken from landing devices or austronafts we see no stars at all when we see plenty of stars in images taken from the earth although earth has thich atmoshpere?
Reply | Report Abuse | Link to thisEver wondered why while everything else moves in curves due to forces, scientists claim light travels in straight line?
Also when scientists claim that 95,5percent of the heat arriving on the surface of earth comes from the sun and only 0,5 per from the core? Shouldnt the surface be hoter at least in the side of the sun?
NASA is keeping secrets from us