Earth's atmosphere came from outer space, find scientists

Dec 10, 2009
Earth

(PhysOrg.com) -- The gases which formed the Earth's atmosphere - and probably its oceans - did not come from inside the Earth but from outer space, according to a study by University of Manchester and University of Houston scientists.

The report published this week in the prestigious international journal 'Science' means that textbook images of with huge volcanoes spewing gas into the atmosphere will have to be rethought.

According to the team, the age-old view that volcanoes were the source of the Earth's earliest atmosphere must be put to rest.

Using world-leading analytical techniques, the team of Dr Greg Holland, Dr Martin Cassidy and Professor Chris Ballentine tested volcanic gases to uncover the new evidence.

"We found a clear signature in volcanic gases," said Dr Greg Holland the project's lead scientist.

"From that we now know that the volcanic gases could not have contributed in any significant way to the Earth's atmosphere.

"Therefore the atmosphere and oceans must have come from somewhere else, possibly from a late bombardment of gas and water rich materials similar to comets.

"Until now, no one has had instruments capable of looking for these subtle signatures in samples from inside the Earth - but now we can do exactly that."

The techniques enabled the team to measure tiny quantities of the unreactive volcanic trace gases Krypton and Xenon, which revealed an isotopic 'fingerprint' matching that of meteorites which is different from that of 'solar' gases.

The study is also the first to establish the precise composition of the Krypton present in the Earth's mantle.

Project director Prof Chris Ballentine of The University of Manchester, said: "Many people have seen artist's impressions of the primordial with huge volcanoes in the background spewing gas to form the .

"We will now have to redraw this picture."

The research was funded by Natural Environment Research Council (NERC).

More information: 'Meteorite Kr in Earth's Mantle Suggests a Late Accretionary Source for the Atmosphere' by Dr Greg Holland and Prof Chris J. Ballentine, journal Science.

Provided by University of Manchester (news : web)

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User comments : 12

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SincerelyTwo
Dec 10, 2009
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MikeyK
Dec 10, 2009
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El_Nose
Dec 10, 2009
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plasticpower
3 / 5 (2) Dec 10, 2009
I find it hard to believe that so much gas and water came from asteroids and comets.
omatumr
1.6 / 5 (7) Dec 10, 2009
Earth accreted heterogeneously (in layers) and the upper mantle melted to form the atmosphere and oceans.

This is the story revealed by the inventory of radiogenic He-4, Ar-40, Xe-129 & Xe-136 and primordial He-3 in the Earth and in its interior today [See: "The noble gas record of the terrestrial planets," Geochem. J. 15, 245-267 (1981)].

With kind regards,
Oliver K. Manuel
Arikin
not rated yet Dec 11, 2009
Why would there be a difference?

The planets in a solar system are all made up of asteroids... What we call asteroids are left overs of planet building. When they start falling back to the planets millions of years later after the planets are fairly settled their compositions are now somehow suddenly different?? Not all asteroids have the same ratios of components??
Parsec
2.3 / 5 (3) Dec 11, 2009
... and the upper mantle melted to form the atmosphere and oceans.


This is the reason that the oceans today are make up of liquid rock and the atmosphere rains rocks when the weather gods get pissed.

Jeez... talk about global warming!
RayCherry
5 / 5 (3) Dec 11, 2009
The origin of the atmosphere has always been thought of as having Earthly origins, that is all the new research is contesting.

Yes, Earth formed by accretion of materials from the original disk of material surrounding the sun. I see nothing in the article that changes that basic idea.

The dry materials, metals, rocks, minerials appear to have formed much closer to the sun than the 'wet' (for the want of a better word) that appears to have formed, or travelled, much further out, as evidenced by the Oort Cloud and Comets.

This article suggests, (to me at least), that our dry, volcanic planet was well formed before our atmosphere arrived in the form of a bombardment of asteroids and comets from the outer solar system.

Simply put, the planet formed from inner solar system materials, but the atmosphere was a gift from much further out ... Earth was in the right place(s) at the right time(s).

This 'somewhat' decreases the odds of life like ours evolving on other planets.
RayCherry
3 / 5 (2) Dec 11, 2009
PS: Congratulations Manchester.

Fundamental research bringing another basic assumption into question and changing knowledge that affects many of the current ideas about Earth and life (foreign or ours) on other worlds.
RayCherry
3 / 5 (2) Dec 11, 2009
Evolution is much more complex than it seemed, and the idea of Terraforming other planets just got a major hint ... time we bombarded Mars (again) with asteroids and comets?

If we are to continue growing the population of our species, we need to collonize other worlds.

That fundamental necessity has been understood for hundreds of years by a growing number of people. Cultural preparation is complete, it is the cost that is holding us back.

Either we start populating another planet, or we employ population conrol here, (remember "Logan's Run"?). Those are our options as an intelligent, responsible, evolving species.
Yellowdart
1 / 5 (1) Dec 11, 2009
The other conclusion is that meteorites came from earth.

If you bought a pair of shoes, and examined the composition to be the quality and made of a pair of Air Jordan's, you would assume they came from a Nike store.

Similiarly, if you find rock of the composition of earth...it's just as plausible it came from earth.
Damon_Hastings
3 / 5 (2) Dec 11, 2009
If we are to continue growing the population of our species, we need to collonize other worlds.

If the human population continues doubling every 50 years, then we'd need 1000 more Earth-sized planets within 500 years, in order to maintain the same population density per square mile. And 1,000,000 planets 1000 years from now. And we'd fill the galaxy within 1500 to 1600 years. We'd convert the entire mass of the universe into human flesh in under 10,000 years (assuming FTL travel).

I'd say colonization is not a viable long-term solution. I doubt we could ship humans to Mars faster than they reproduce on Earth any time in the foreseeable future. And if there are aliens, they probably wouldn't allow us to expand beyond our own solar system without a permit or something. At some point, we have to just take responsibility for reigning in our own reproduction.
SteveL
2 / 5 (1) Dec 11, 2009
Is it possible that the earth's gravity may have picked up stellar material over a few billion years (mainly hydrogen and carbon) from the slowly stablizing proto-sun to later source its atmosphere after photosynthesis started? Seems like asteroidal and cometary sources wouldn't be sufficient as a sole source when considering the minute quantities they contain of the needed materials.

I'm thinking that a gravitational source flowing through even a thinly dispursed elemental bath being held away from the sun by solar winds would over billions of years acquire quite a collection of the needed components that after later photosynthesis makes up our present atmosphere.
googleplex
2 / 5 (1) Dec 11, 2009
The other big puzzle about earth is its hot iron core. Firstly why do we have so much more iron than the other planets. Secondly why is it still hot and not cold.
I am thinking that we have a hot little nuclear rx going on there. U being more dense than Fe so it would concentrate in the center of the earth core. The vast amount of mantel would shield the tell tale nuclear radiation.
omatumr
1 / 5 (3) Dec 11, 2009
The other big puzzle about earth is its hot iron core.


1. Earth's iron core apparently accreted directly from iron meteorites [See: K. K. Turekian and S. P. Clark, Jr., "Inhomogeneous accumulation of the earth from the primitive solar nebula," Earth & Planetary Science Letters 6 (1969) 346-348].

2. Stellar ejecta from near the core of a supernova formed iron meteorites without ever mixing the iron with other elements. That seems to be the only viable explanation for the existence of molybdenum isotope anomalies from stellar nuclear reactions in massive iron meteorites [See: Qi-Lu, Doctoral Dissertation, The University of Tokyo (1991) and confirmation made by other laboratories and published in Nature 415 (2002) 881].

With kind regards,
Oliver K. Manuel