Earth - What is the real age?

[David Levy]

What is the real age of Earth?

 

By wiki: http://en.wikipedia.org/wiki/Earth

"According to evidence from radiometric dating and other sources, Earth was formed around four and a half billion years ago. Within its first billion years,^[37]life appeared in its oceans and began to affect its atmosphere and surface, promoting the proliferation of aerobic as well as anaerobic organisms and causing the formation of the atmosphere's ozone layer."

Is it possible that in just one billion year from its creation, the Earth was cool enough to sustain ocean?

The temperature at the center is as follow:

"At the center, the temperature may be up to 6,000 °C (10,830 °F),^[78] and the pressure could reach 360 GPa.^[79] Because much of the heat is provided by radioactive decay, scientists postulate that early in Earth's history, before isotopes with short half-lives had been depleted, Earth's heat production would have been much higher. This extra heat production, twice present-day at approximately 3 byr,^[76] would have increased temperature gradients with radius, increasing the rates of mantle convection and plate tectonics, and allowing the production of uncommon igneous rocks such as komatiites that are rarely formed today"

Hence, in the past, the temperature at the center was much higher than 6000 °C.

However, the Earth has Iron inner core.

"Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the magnetic field, and a thick layer of relatively solid mantle"

This might be an indication that the earth was a full hot star in order to concentrate the iron in the core (by gravitational force).

Gradually, the earth cool down and set his unique structure:

Earth-cutaway-schematic

http://en.wikipedia.org/wiki/File:Earth-cutaway-schematic-english.svg

So, how long it should take the Earth to cool down from a full hot star at high temperature of over 6000 °C?

How could it be that in just one billion year it was cool enough to sustain ocean and even the first form of life? Did we try to make a simulation of this important process?

Edited March 23, 2015 by Phi for All
reduced "yelling" font size

[studiot]

This is where lord Kelvin went wrong 100+ years ago

 

http://apps.usd.edu/esci/creation/age/content/failed_scientific_clocks/kelvin_cooling.html

[Acme]

This might be an indication that the earth was a full hot star in order to concentrate the iron in the core (by gravitational force. ...

No, Earth was never a star.

Here is an in-depth simulation of the core formation. >>Numerical Simulation of Earth's Core Formation

[pavelcherepan]

 

 

Is it possible that in just one billion year from its creation, the Earth was cool enough to sustain ocean?

 

It is actually very possible that the Earth was cool enough to have water and oceans about 100-150 million years after formation, which is based on studies of oldest known zircon crystals:

 

http://geoscience.wisc.edu/geoscience/people/faculty/john-valley/a-cool-early-earth/

 

Prior to that the Earth might have been partially or completely molten due to the Giant Impact that formed the Moon and in general impacts with smaller bodies during initial coalescence stage.

 

Also the Iron Catastrophe at a later time could've lead to formation of magma ocean.

 

http://astro.hopkinsschools.org/course_documents/earth_moon/earth/geologic_time/iron_catastrophe.htm

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988LPICo.681...20G&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES

 

In any case the oldest known rocks are some 4 bya and oldest evidence of life in the form of stromatolites is some 3.5 bya.

 

http://www.nature.com/nature/journal/v441/n7094/full/nature04764.html

Edited March 24, 2015 by pavelcherepan

[David Levy]

Thanks

Let's assume that in the past the earth was covered by ocean of magma at the same temperature as the core.

http://en.wikipedia.org/wiki/Giant_impact_hypothesis

"There remain several questions concerning the best current models of the giant impact hypothesis, however.^[6] The energy of such a giant impact is predicted to have heated Earth to produce a global 'ocean' of magma"

 

How could it be that it cools down dramatically in only 100 million years?

 

http://en.wikipedia.org/wiki/Late_heavy_bombardment

"Later calculations showed that the rate of collapse and cooling depends on the size of the rocky body. Scaling this rate to an object of Earth mass suggested very rapid cooling, requiring only 100 million years.^[14] The difference between measurement and theory presented a conundrum at the time".

 

Is it real that by so short period of time a magma ocean had been replaced by real water ocean?

Edited March 24, 2015 by David Levy

[Acme]

Thanks

Let's assume that in the past the earth was covered by ocean of magma at the same temperature as the core.

http://en.wikipedia.org/wiki/Giant_impact_hypothesis

"There remain several questions concerning the best current models of the giant impact hypothesis, however.^%5B6%5D The energy of such a giant impact is predicted to have heated Earth to produce a global 'ocean' of magma"

 

How could it be that it cools down dramatically in only 100 million years?

 

http://en.wikipedia.org/wiki/Late_heavy_bombardment

"Later calculations showed that the rate of collapse and cooling depends on the size of the rocky body. Scaling this rate to an object of Earth mass suggested very rapid cooling, requiring only 100 million years.^%5B14%5D The difference between measurement and theory presented a conundrum at the time".

 

Is it real that by so short period of time a magma ocean had been replaced by real water ocean?

It's real[istic], yes. I just referenced a detailed paper in another thread that has calculations for the solidifying of a planetary crust. In this paper the critical factor considered is the distance between the planet and its star. The paper is free to read online but no copying or pasting allowed so I'll give that link here.

>>-Emergence of two types of terrestrial planet on solidification of magma ocean

[Robittybob1]

It's real[istic], yes. I just referenced a detailed paper in another thread that has calculations for the solidifying of a planetary crust. In this paper the critical factor considered is the distance between the planet and its star. The paper is free to read online but no copying or pasting allowed so I'll give that link here.

>>-Emergence of two types of terrestrial planet on solidification of magma ocean

That link didn't work for me. Is this a different one?

http://www.nature.com/nature/journal/v497/n7451/full/nature12163.html

[Acme]

That link didn't work for me. Is this a different one?

http://www.nature.com/nature/journal/v497/n7451/full/nature12163.html

Don't know why it won't work for you. ? Your link is just the abstract, mine the full paper. Try right-clicking on my link, click Properties, and copy the url and then paste it into your browser address bar.

[pavelcherepan]

Let's assume that in the past the earth was covered by ocean of magma at the same temperature as the core.

 

What core temperature are you referring to? Modern day?

 

 

 

How could it be that it cools down dramatically in only 100 million years?

 

This paper, for example, suggests it would be possible to return to partially crystalline state in just 30 my (plus or minus 10).

 

http://www.nature.com/nature/journal/v437/n7063/full/nature04129.html

 

The next study with highly technical calculations suggests a cooling time of ~100 my (that including the 'precipitation' of evaporated silicate rocks).

 

https://books.google.com.au/books?

hl=en&lr=&id=8i44zjcKm4EC&oi=fnd&pg=PA179&dq=%22giant+impact%22+%26+%22cooling%22&ots=7J7G5oM4kO&sig=wwNA70Ueg5akNq0HCdlX_wD6fPU#v=onepage&q=%22giant%20impact%22%20%26%20%22cooling%22&f=false

 

And here you also have some studies on thermal equilibrium, molten surface and what effect water had on all of it.

 

http://www.jstor.org/discover/10.2307/74159?sid=21106221504453&uid=3737536&uid=4&uid=2

http://www.sciencedirect.com/science/article/pii/S0012821X99001569

http://adsabs.harvard.edu/abs/2000orem.book..413A

[Robittybob1]

Don't know why it won't work for you. ? Your link is just the abstract, mine the full paper. Try right-clicking on my link, click Properties, and copy the url and then paste it into your browser address bar.

That just took me back to where I was before

The error message I get is after clicking on "Download PDF" "You are viewing a complimentary shared article, since we have detected that you would not normally have full-text access. Complimentary shares do not allow PDF file downloads. Click here for additional access options."

Are you a subscriber?

Edited March 24, 2015 by Robittybob1

[Acme]

If that doesn't work, I found my link embedded in this article. >> Venus Too Close To Sun Ever To Have Hosted Oceans & Life, New Study Suggests Scroll down and click on the blue words Venus was probably doomed.

That just took me back to where I was before

The error message I get is after clicking on "Download PDF" "You are viewing a complimentary shared article, since we have detected that you would not normally have full-text access. Complimentary shares do not allow PDF file downloads. Click here for additional access options."

That's a header page to the article and from that you do have to pay, however my link is a special share page set up that lets you read the paper, but not download or copy it. Try the other route I just posted. I have the paper pulled up on 3 tabs so I can't say what the problem is on your end.

[Robittybob1]

If that doesn't work, I found my link embedded in this article. >> Venus Too Close To Sun Ever To Have Hosted Oceans & Life, New Study Suggests Scroll down and click on the blue words Venus was probably doomed.

 

That's a header page to the article and from that you do have to pay, however my link is a special share page set up that lets you read the paper, but not download or copy it. Try the other route I just posted. I have the paper pulled up on 3 tabs so I can't say what the problem is on your end.

Still doesn't work. Unless I wanted to pay of course. Don't worry.

[pavelcherepan]

Still doesn't work. Unless I wanted to pay of course. Don't worry.

 

That's odd. It worked for me yesterday and now it doesn't.

[swansont]

How could it be that it cools down dramatically in only 100 million years?

 

The short answer is that bodies radiate as T⁴ (space is very cold, so the incoming radiation from space is negligible). That is a body at 1200K radiates ~300x as much power as one at 290K.

[Robittybob1]

 

The short answer is that bodies radiate as T⁴ (space is very cold, so the incoming radiation from space is negligible). That is a body at 1200K radiates ~300x as much power as one at 290K.

Briefly how would the Earth's atmosphere affect that radiation rate? Is it going to be at the same ratio regardless?

[swansont]

Briefly how would the Earth's atmosphere affect that radiation rate? Is it going to be at the same ratio regardless?

That will affect it somewhat, but it depends on what the atmosphere like back then. What I described would still hold for clear skies (especially at night). The point being that the relationship is not linear. Doubling the temperature leads to 16x the power loss, so hot things will cool rapidly when radiation is dominant.

[David Levy]

 

The short answer is that bodies radiate as T⁴ (space is very cold, so the incoming radiation from space is negligible). That is a body at 1200K radiates ~300x as much power as one at 290K.

 

 

O.K.

Let's agree that the Earth had been cooled down from 6000 °C to 32 °C in 100 My. Hence, by average, the temperature had been decreased by 59.68 °C per My. As the space is still very cold, it is expected that the Earth will continue with its rapid heat lose. Therefore, after 110 M years the temperature should be around -68 °C and after 150 My -266.4 °C.

However, based on our knowledge, this isn't the case.

So, the Earth had been cooled down from over 6000 °C (or even 10,000 °C) to 32 °C in less than 100 My, and for 4.5 Billion years it holds the temperature at the same level (more or less).

Wow, is it real?

Edited March 24, 2015 by David Levy

[ajb]

So, the Earth had been cooled down from over 6000 °C (or even 10,000 °C) to 32 °C in less than 100 My, and for 4.5 Billion years it holds the temperature at the same level (more or less).

Wow, is it real?

Think about the energy we receive from the Sun.

[David Levy]

Think about the energy we receive from the Sun.

Where was it in the first 100 My?

[Greg H.]

 

 

O.K.

Let's agree that the Earth had been cooled down from 6000 °C to 32 °C in 100 My. Hence, by average, the temperature had been decreased by 59.68 °C per My. As the space is still very cold, it is expected that the Earth will continue with its rapid heat lose. Therefore, after 110 M years the temperature should be around -68 °C and after 150 My -266.4 °C.

However, based on our knowledge, this isn't the case.

So, the Earth had been cooled down from over 6000 °C (or even 10,000 °C) to 32 °C in less than 100 My, and for 4.5 Billion years it holds the temperature at the same level (more or less).

Wow, is it real?

 

That would only hold true if we weren't bathed in heat sources. We receive heat from the sun, as well as from decaying radioactive material in the planet itself. Also, the heat loss falls off, as was pointed out, as the temperature difference decreases.

[imatfaal]

 

 

O.K.

Let's agree that the Earth had been cooled down from 6000 °C to 32 °C in 100 My. Hence, by average, the temperature had been decreased by 59.68 °C per My. As the space is still very cold, it is expected that the Earth will continue with its rapid heat lose. Therefore, after 110 M years the temperature should be around -68 °C and after 150 My -266.4 °C.

However, based on our knowledge, this isn't the case.

So, the Earth had been cooled down from over 6000 °C (or even 10,000 °C) to 32 °C in less than 100 My, and for 4.5 Billion years it holds the temperature at the same level (more or less).

Wow, is it real?

 

I am not sure you understood SwansonT's point about temperature dependence. In Kelvin the loss of heat is proportional to the FOURTH power of the temperature. You cannot take the entire change in T and the entire time and just average.

 

http://www.wolframalpha.com/input/?i=plot+y%3Dx%5E4+0+to+6500

 

Here is a graph of y=x^4 from 0 to 6500. This vaguely approximates the heat loss - you can use it to understand the ratio of different rates of heat loss (y) for different temperatures (very very roughly) You will note that from about 0-1000 on the x axis you cannot even see the line it is so close to zero on the y axis

[Greg H.]

Where was it in the first 100 My?

It was there, but it wasn't enough to keep the planet from radiating out massive amounts of heat into space.

 

So if you have heat coming in, and heat radiating out, the temperature will either rise or fall (depending on which of those values is higher) until they balance each other.

[Acme]

...So, the Earth had been cooled down from over 6000 °C (or even 10,000 °C) to 32 °C in less than 100 My, and for 4.5 Billion years it holds the temperature at the same level (more or less).

Wow, is it real?

As the others pointed out, the relationship isn't linear. Here's another perspective.

 

Earth's energy budget: >> http://en.wikipedia.org/wiki/Earth's_energy_budget

...

Received radiation is unevenly distributed over the planet, because the Sun heats equatorial regions more than polar regions. Energy is absorbed by the atmosphere and hydrosphere, known as Earth's heat engine, coupled processes which constantly even out solar heating imbalances through evaporation of surface water, convection, rainfall, winds, and ocean circulation, when distributing heat around the globe. When incoming solar energy is balanced by an equal flow of heat to space, Earth is in radiative equilibrium and global temperatures become relatively stable.

 

Disturbances of Earth's radiative equilibrium, such as the rise of heat-trapping gases, change global temperatures in response, because of the greenhouse effect, since energy radiated back to space is in part absorbed by greenhouse gas molecules.[4] However, Earth's energy balance and heat fluxes depend on many factors, such as the atmospheric chemistry composition (mainly aerosols, and greenhouse gases), the albedo (reflectivity) of surface properties, cloud cover, and vegetation and land use patterns. Changes in surface temperature due to Earth's energy budget do not occur instantaneously, due to the inertia (slow response) of the oceans and the cryosphere to react to the new energy budget. The net heat flux is buffered primarily in the ocean's heat content, until a new equilibrium state is established between incoming and outgoing radiative forcing and climate response.[5]

...

As to heat coming from the core, this:

Geothermal gradient

 

...

Temperature within the Earth increases with depth. Highly viscous or partially molten rock at temperatures between 650 to 1,200 °C (1,200 to 2,200 °F) is postulated to exist everywhere beneath the Earth's surface at depths of 80 to 100 kilometres (50 to 60 mi)[citation needed], and the temperature at the Earth's inner core/outer core boundary, around 3,500 kilometres (2,200 mi) deep, is estimated to be 5650 ± 600 kelvins.[6][7] The heat content of the Earth is 10³¹ joules.[1]

■ Much of the heat is created by decay of naturally radioactive elements. An estimated 45 to 90 percent of the heat escaping from the Earth originates from radioactive decay of elements mainly located in the mantle.[4][8][9]

■ Heat of impact and compression released during the original formation of the Earth by accretion of in-falling meteorites.

■ Heat released as abundant heavy metals (iron, nickel, copper) descended to the Earth's core.

■ Latent heat released as the liquid outer core crystallizes at the inner core boundary.

■ Heat may be generated by tidal force on the Earth as it rotates; since rock cannot flow as readily as water it compresses and distorts, generating heat.

■ There is no reputable science to suggest that any significant heat may be created by electromagnetic effects of the magnetic fields involved in Earth's magnetic field, as suggested by some contemporary folk theories.

...

Edit: fix link

Edited March 24, 2015 by Acme

[David Levy]

 

That would only hold true if we weren't bathed in heat sources. We receive heat from the sun, as well as from decaying radioactive material in the planet itself. Also, the heat loss falls off, as was pointed out, as the temperature difference decreases.

 

Excellent answer!

So we have two elements:

-"Sun heat contribution" and

-"The heat loss falls off, as the temperature difference decreases".

Let's start with the first element:

Sun heat contribution – for the last 4.4 Billion years the sun keeps the earth at the same temperature (more or less). With this assumption, even if we go back 100 Billion year, than the temperature on Earth should be the same. However, somehow, we must increase this temperature. Therefore, let assume that the max temperature to hold life is 50 °C. That was 3.5 Billion years ago.

So, 3.5 Billion years ago, the temperature was 50 °C. If the temperature today is 30, then it had been decreased by 20 °C in 3.5 Billion years.

Now, let use the second section:

The heat loss falls off, as the temperature difference decreases- So, in 3.5 Billion, the temperature had been falls by 20 °C .

Let's use 3.5 Billion year as a constant time segment and the 20 °C as heat increase segment.

Let's assume that as we move backwards in time, for each constant time sector, the heat increase should be doubled.

Hence,

At 7 billion years ago, the temperature was 50 + 2x20 = 90 °C (Heat increase 90-30= 60 °C)

At 10.5 billion years ago, the temperature was 90 + 2x60 = 210 °C (Heat increase 210-30= 180 °C)

At 14 billion years ago, the temperature was 210 + 2x180 = 570 °C (Heat increase 570-30= 540 °C)

At 17.5 billion years ago, the temperature was 570 + 2x540 = 1650 °C (Heat increase 1650-30= 1620 °C)

At 21 billion years ago, the temperature was 1650 + 2x1620 = 4890 °C

Therefore (under those assumptions) about 20 billion years are needed to decrease the temperature from about 5000 to 30. Somehow, 100 M years is not enough!

Edited March 24, 2015 by David Levy

[Acme]

Sun heat contribution – for the last 4.4 Billion years the sun keeps the earth at the same temperature (more or less). With this assumption, even if we go back 100 Billion year, than the temperature on Earth should be the same. ...

The solar system is only 4.6 billion years old so there is no going back to 100 billion.

.

Are you trying to understand what is known and how, or are you trying to contest it with your own speculation?

Edited March 24, 2015 by Acme