Planetary atmospheres

 

For the investigation of geological questions, it can be of value to take a look at other objects in our solar system.  One will notice the numerous possibilities which existed in the early stages of the origin of our solar system.  Seen from this standpoint, it becomes conceivable that, in the earliest times of the earth, entirely different circumstances may have prevailed regarding the atmosphere and formation of the surface.

The most striking phenomena of the solar system can be brought into our view by taking an imaginary journey, beginning with a visit to the sun.

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The pictures of the sun shown above are not taken with an attenuating filter, but ather with ultraviolet and Röntgen cameras which observe the shorter-wave radiation spectrum.

The mass and extent of the sun is unbelievably large in comparison to our usual experiences.  The days-long rocket journeys of astronauts would serve only to travel across a small segment of the sun’s surface.  We speak of the „ball of the sun“, but the expression conceals the fact that, already with a depth of a few thousand kilometers below the sun’s surface, there prevail conditions which escape our imaginings or earthly conceptions.  One speaks of „hydrogen“, of course, but the form of this hydrogen is so removed from the earthly gas hydrogen, that one does as well to speak only in abstract numbers of „proton densities“, „particle velocities“, etc.  Nevertheless an attempt at a description will be made: The sun consists- if one ignores the most inward zones- of hydrogen and a small component of helium.  In the innermost zones the sun, under the influence of the enormous temperature and density, a small amount of the „lighter“ hydrogen shifts over to the condition of the somewhat denser helium substance (fusion).  With this transformation of substance there also takes place a transformation of mass into radiant energy.  The total weight of the resulting helium is very slightly less than that of the starting material, although in a noteworthy symmetry the density or heaviness of the the material has increased (helium is denser than hydrogen).

The short-waved radiation energy so generated thansforms itself in its path to the outer layers of the sun into „normal“ light and warmth, resulting in huge convection currents of hydrogen on the surface, giving the granular structure visible in the pictures.  These currents lead, as in a dynamo, to electromagnetic effects which build up a complex magnetic field system.   This magnetic field covers the entire sun like a thick fabric, and in the course of twice eleven years completes a predictable transformation cycle.   The bow-shaped or plume-shaped flames which can arise and disappear within hours, days or months, maintain their form through this magnetic field system.  They release billions of tons of ionized hydrogen daily, which is strewn out into space as a finely-dispersed „solar wind“, with a velocity of several hundred kilometers per second, travelling through the entire solar system.  The corona (the light crown visible during a solar eclipse) and the northern lights on earth are consequences of this „wind“, which can also be considered as a type of „slow radiation“.

The planetary journey goes next to the planet Mercury, closest to the sun, whose moon-klike surface posesses no atmosphee.  The full strength of the solar wind, unimpeded by athe weak magnetic field, combined with the high temperature and small gravitational field, make a gas layer impossible.  In the shade of crater edges frozen water, ice, seems to have been deposited.  Since the rotation of Mercury, similar to our own moon, seems to have come almost to a complete stop, a Mercury „day“ lasts almost half an earth year.

Venus, the next planet outward from Mercury, posesses an opaque atmosphere of crbon dioxide and some nitrogen, with a very high-lying cloud layer of sulfuric acid.  The Venus atmosphere is significantly thicker than that of the earth, so that the air pressure over the desert-like surface is ninety times higher than ours.  The greenhouse effect allows a temperture of up to 460 degrees celsius, corresponding to the heat of a fireplace.  Giant extinct volcanoes and hardened lava flows testify to an expulsion of magma, which surprisingly did not take place all that long ago, and covered almost the entire planetary surface.  The carbon dioxide of the Venus amosphere may have its origins with these eruptions .

Venus-Atmosphere of carbon dioxide

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The journey goes on further to Mars, which is surrounded by a layer consisting primarily of carbon dioxide.  It is 160 times thinner than the atmosphere of the earth, and covers an ice-cold surface consisting of deserts, rock and individual regions covered by dunes.  It nevertheless is able to develop a meager „climate“ which can exhibit hoarfrost and snow-formation as well as dust storms.  Giant streambeds testify to a past flow of water, which are nevertheless not comparable to those of our preent-day rivers.  Models postulate that Mars once posessed a shallow ocean of prhaps 500 m. Depth, and may have posessed a thicker atmosphere as well.  Recent discoveries point to the possibility of great masses of frozen water underneath the desert-like surface.  On Mars is the largest volcano in the solar system, with a surface area the size of Texas, and at 25 kilometers height is double that of the largest Pacific volcanoes.


Mars surface with channels and erosional areas

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Jupiter, the innermost of the so-called „gas planets“, posesses a gigantic atmosphere, which in its outermost layers contains clouds of nitrogen and sulfur compounds, as well as particles of dust.  Further below are cloud layers composed of water, below which comes the actual hydrogen-helium atmosphere with traces of ammonia and methane, which at a depth of perhaps 1000 kilometers becomes fluid under the enormous pressure.  The topmost atmosphere is divided into multiple „trade wind“ and storm vortex zones.  The largest storm vortex, the „great red spot“, has raged for three hundred years and is as large as the entire earth.  It draws in and consumes neighboring storm vortices, and may maintain its energy through other maechanisms as well.  Its red coloring may stem from organic substances or from phosphorus, which has separated out chemically due to lightning.  Since there are, in the interior of the planet, giant streams of highly densified, electrically-conductive hydrogen, Jupiter posesses an unusually strong magnetic field, which has its effect on other aspects of the planet, and on its moons.

Jupiter with storm vortices

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Of the moons of Jupiter, Io will be mentioned first.  It possesses only a very thin atmosphere, but an unusually large volcanic activity.  Its yellow, red and black speckled surface has scattered seas and deserts of sulfur and sulfur compounds.  From numerous active volcanoes, masses of sulfur are thrown out for hundreds of kilometers, before falling to the surface as sulfur rain.  At the same time, in the course of months, regions the size of Iceland are overflooded with dark, silicatic magma masses.  Flows hundreds of kilometers long consisting of a very hot, dense fluid have been observed.  This unusual moon has possibly remained active due to the gravitational forces of Jupiter and the neighboring moons, which have penetrated Io from earliest times, creating deformations during the revolving movements which maintained its temperature.

Jupiter moon Io with sulfur volcanoes

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The appearance is entirely different on Jupiter’s moon Europa, which is surrounded by a thick, blue-brown armor of ice.  Kilometer-wide trenches cut into the surface for lengths of hundreds of kilometers, bordered on each side by ice-walls one- to two hundred meters high.  The gravitational forces of Jupiter appear to have warmed the moon and perhaps kept the water under the ice-armor in a fluid condition, so that the outer shell may have broken apart a relatively short time ago, allowing slush and water to flow out over the surface.  The depth of the oceans is estimated at up to one hundred kilometers (the earth’s ocean is an average of four kilometers deep).

Jupiter moon Europa with ice armor

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The two additional moons of Jupiter, Ganymed and Callisto, have similar sizes, and show the existence above the surface of silica rocks a large amount of water in the form of ice and ice-rock mixture.

 

Saturn, the second large gas planet of the solar system, has a storm-permeated hydrogen-helium atmosphere similar to Jupiter’s.  The highest layers of clouds consist in part of the nitrogen compound ammonia.   The planet is surrounded by thousands of rings, made up of dust, sand and ice particles, or rock fragments covered with ice.  In part they are held together in their bands by the small neighboring moons.  The ring system may consist of earlier moons pulled apart by gravitational forces, or from older material which never was able to condense to form a moon.

Saturn with ring system

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Saturn’s largest moon, Titan, is larger than the planet Mercury, and is the only moon in the solar system to posess an atmosphere.  It consists primarily of nitrogen, as with the earth’s atmosphere.  In addition, there is methane and other gases.  Fluid methane and ice have been observed, or at least suspected, on the surface (Cassini mission).

Saturn’s second-largest moon, Rhea, consists to a large extent of frozen water.  It circles saturn at a similar distance to the ice-covered moon Europa of Jupiter.

Die Saturn moons Titan and Rhea

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Uranus and Neptune, also both gas planets, shimmer in blue due to a small amount of methane in the predominantly hydrogen-helium amosphere.  In contrast to Uranus, Neptune appears to posess its own source of heat, and in consequence of the resulting climate is circled by fast-moving methane cirrus clouds in its upper atmospheric layers.  In addition, a giant rotating storm has been visible for years as a dark-blue spot.  Below the atmospheres of Neptune there is thought to be an ocean of hot water, ammonia, methane and hydrogen sulfide, thousands of times deper than our own ocean, and at the base passes over into a „solid“ condition.  Another model postulates solid mantle shells made up of various substances, and moving like glacier ice in slow flowing movements, creating in this way the unique, four-part magnetic field of the planet.  Besides its ring system, Saturn posesses another unique attribute: the axis of rotation is at right angles to its axis of revolution around the sun, making it appear to roll like a wheel along its path of revolution for certain stretches.  It is suspected that an earlier collision with another body led to this condition.

  Uranus with ring (left) und Neptune with large blue spot (right)

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The final, small planet Pluto rotates in an eccentric orbit around the sun, tipped at a large angle relative to the other planetary orbits.  Thus at times it is closer to the sun than its neighbor Neptune, and its own rotation is in the opposite direction to the other planets, possibly as a result of an earlier collision.  It apparently has no atmosphere, but rather a surface formed of various forms of ice (frozen gases).  Pluto and its small moon Charon ( other small moons have recently been discovered) have the same side turned to each other, and thus form a system which has come to rest, and rotates around itself in the course of several days.

Many other objects in the solar system remain to be described: kilometer-thick comets formed of ice, which rotate around the sun on elliptic orbits, or remain forever invisible in their environment outside the orbit of Pluto; asteroids of nickel-iron or rock, with dimensions of from a few to dozens of kilometers, which travel along their irregular orbits between Jupiter and Mars as the debris of an earlier planet, or as one that never coalesced, etc.

As one can see from these descriptions, no two planets or bodies are alike.  Even small differences in initial conditions have led to the creation of very different objects, surfaces and atmospheric layers.  In addition, it can be assumed that each has gone through the most varied paths of development.  Considering these objects wakes a sense that their history has been a very lively and complicated one, calculable only with difficulty.  For example, gravitational forces may lead to a warming of the interior, leading under circumstances to a hot-fluid iron core, creating in turn a magnetic field which fends off the solar wind and allows processes to proceed differently in the atmosphere.  Such examples could be extrapolated endlessly, if we only had the necessary knowledge.

What impression does one receive as a whole from the described objects?  With respect to the finely tuned balance prevailing on the earth, and the somewhat „one-sided“ impression given by the other planets and their moons, one could receive the impression of a „construction-world“.  These other objects circle like left-over pieces around the sun- the one too small, the other too large to possess life.  The one has huge quantities of frozen water, another seas of sulfur, a third methane vapors.  Some glow with the heat of a fire, others lie in ice-cold rigidity.  It appears as though these bodies each went on a certain one-sided path, while the earth was able to hold to a middle way.  These others thus became uninhabitable, unsuitable for an enduring and complex life.  They may, however, at particular times gone through similar developments as the earth, and may shelter perhaps the first rudimentary stages of a living self-organization.

The earth and its surface

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Turning our thoughts back to the earth, let us consider the earliest periods of the planet.  How does one picture today the conditions prevailing at that time?  The present conceptions present roughly the following development:  In a first phase after the formation of the primeal sun and planets out of interstellar dust and gas clouds, themselves the result of earlier supernova explosions, there reigned at first a chaotic condition with innumerable small bodies in irregular orbits, steroid impacts, alterations of the planetary orbits and speeds,etc.  The size and composition of the individual planetary atmospheres cannot be determined in detail.  After a certain period of coming to rest, i.e. after many wandering bodies had been absorbed, the planetary orbits became somewhat stabilized and the remaining interplanetary gas removed by the newly-arisen solar wind, the earth, from which the moon had already separated, would have had a primeval atmosphere, at first marginal, but after hundreds of millions of years of the expulsion of gases from the earth, which in the meantime had become fluid-hot, this atmosphere would have become much larger and more inclusive of substances.  These substances would have been, above all, steam, hydrogen, hydrogen chloride, carbon monoxide, carbon dioxide nitrogen and various gases in smaller quantities.  To this was added (according to a more recent model) a equally-lengthy bombardment by small comets, whose water increased that of the atmosphere and ultimately filled the ocean basins.  At first there was little free oxygen.   The arising of life with its assimilating processes then led to a steady increase in the amount of oxygen in the atmosphere, and a decrease in carbon dioxide, which became bound in fossil form to the earth as carbonate sediments, coal, oil, natural gas, etc.  Thus basically, according to the current model, the atmosphere has consisted for long periods now primarily of nitrogen, an increasing percentage of oxygen, a decreasing percentage of carbon dioxide, several percent water and smaller amounts of other gases.  All of this is contained n a thin layer roughly 30 to 40 kilometers thick around the earth, proportional to a millimeter-thick layer around a soccer ball.

If one compares this to the planets and moons described earlier, with their frequently thick atmospheres showing signs of change over time, one could come to the following question:  did the conditions of the early solar system perhaps also allow the possibility, that the atmosphee of the earth had entiely other dimensions and chemical „composition“, or qualities of substantiality, s is the case today?  Naurally there are boundaries to the physical possibilities, but neither the investigation of the earliest earth rocks nor the form of the present atmosphere lead to the conclusion, that the extent of possibilities is only a narrow one.

The pictures below show a sketch of a possible earlier atmosphere alongside that of the present atmosphere of the earth.

Possible primeval atmosphere present-day atmosphere
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The right-hand picture shows how thin and seemingly vulnerable the present atmosphere is.   The thought is remarkable, that the hypothetical atmosphere on the left with its two thousand kilometer thickness, in comparison with the many-thousand kilometer thick atmospheres of Uranus and Neptune, shows a still-modest proportion, and yet in comparison with the present-day atmosphere is gigantic.  Depending on the chemical-qualitative circumstances and temperature, such an atmosphere may have reached the density of a fluid above the firm or malleable surface of the earth.  But what fluid?  In what condition would such a gas mixture of water vpor, hydrogen, hydrogen chloride, carbon monoxide, arbon dioxide, nitrogen and other materials possible present at that time be in at the bottom, if the thicknes of the gas layer were, for example, two thousand kilometers thick?  It would be difficult to say, since neither the exact composition of the atmosphere nor the temperature and other controlling factors are known.  Influences may also have come from the sun or other bodies, which can no longer be determined.  With Jupiter’s moon Io all the factors have led to a large concentration of sulfur, with europa and Ganymed, Callisto (Jupiter) and Rhea (Saturn) to a strong concentration of water and frozen water, with Titan (Saturn) finally to a thick atmosphere of nitrogen and methane.  On Mars it appers that large quantities of water were present, which have disappeared or are hidden under the surface.  What path did the earth follow?

Let us take another look at the phenomena of the water-rich moons and rings of the gas giants Jupiter and Saturn.  The picture below shows a possible ancient condition, for example, of the surroundings of Jupiter in the first periods of the origin of its moons.   As today water-rich rings of dust and rock circle around Saturn, so there could have been, in the earliest times, much larger water vapor and dust rings around both of the hydrogen-helium gas giants Jupiter and Saturn, out of which the moons gradually condensed.  It is conceivable that in the earlist times these moons posessed their own large atmospheres (remnants of which remain on Io and Titan), which gradually, through cooling and gravitation were bound as water oceans on the surface, or through opposing influences dispersed into space.

Drawing: primeval Jupiter with ring spheres of the later moons Io, europa, Ganymed and Callisto; between them gas rings which with time have dispersed.

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An analogous process could be thought of for the entire solar system, in that, in the earlist periods water and other gases, as well as dust, circled the developing sun in huge ring systems.  Here as well there would have been a large hydrogen-helium concentration in the center, with the difference that this concentration reached the point of hydrogen fusion and the beginning of radiation as a sun.  The picture below, meant as a schematic representation, shows the inner four planets, Mercury, Venus, the Earth and Mars, in the beginning of their coalescing out of the existing ring spheres.  In between are rings which, through the influence of solar wind and gravitational effects, later dispersed.

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The arising planets could later have acquired large gas atmospheres (with high pressure in the lowest zones), with a significant water content as in the „Jupiter model“.

Sun- and Earth-origin out of ring- und lens-systems, at first with flattening, then with mega-atmosphere formation on the primeval Earth

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The thought could be furthered with the following consideration:  the fact that 15% of the water content of the earth is in the form of „ground water“ within the crust of the earth (reaching into great depths, only marginally accessible, origin not certain), and that further an astounding 50% of the earth’s crust is oxygen, seen chemically, and that finally, since earliest times free hydrogen, released through cosmic rays, has escaped out into space, could lead to the possibility that the above-mentioned hypothetical water-primeval-atmosphere was in part deposited as oxygen in rocks or as released as hydrogen into space.  The part not distroyed would constitute the present water of the oceans and earth crust.

In this sense the following working hypothesis could be presented: The atmosphere of the earth was, in the earliest times of the formation of the present crystalline rocks and first crustal elements, significantly thicker and denser than today.  Its composition as well as substantial quality were such, that in the lowest zones, due to extreme pressure, it was of a fluid-like consistency.  Correspondingly, the origin of the geological formations of the Archaen (and possibly into the Proterozoic or later)are to be thought of in connection with the conditions of such an atmosphere.

It would also be conceivable that the lowest zones of this primeval atmosphere, in addition to water, carbon, nitrogen, fluorine, phosphorus, sulfur and other non-metallic compounds, also could have contained heavier materials, which under the proper conditions could have been deposited out as rock-forming substances, materials such as sodium, magnesium, aluminum, silicon, potassium, calcium and even metals such as iron, copper, silver, etc.  In this case not all crust and mantle substances would have been contained from the beginning in a compact earth body, but rather gradually layered on.

With such conceptions, certain basic geological questions can be considered again.  The chondrites (stony meteorites) and the rock material of comets point in principle to a primary mineral formation directly out of the interstellar gas mixture, without a detour through a magmatic fluid state.  Certain upper rock layers of the early earth, in analogy to this, could have been deposited directly out of such a dense atmosphere, layered onto the surface of the planet, and only later metamorphosed.  The growth of the earliest cratonic, silica-rich continental regions, would then not be explained through differentiation based on density and enrichment through subduction cycles, but rather also by „differentiation from above“, out of the atmosphere.  Certain questions, for instance those involving extremely large-surfaced granite, gneiss, quartzite, schist or sandstone complexes in particular regions of the earth could be considered anew from the aspect of such atmospheric depositional processes.

With the concept introduced here of a thick, dense primeval atmosphere with rock-forming precipitations, on is (as mentioned in the chapter „H2O once different“) close to the picture presented by Rudolf Steiner from his spiritual-scientific research: A life permeated, airy-watery atmosphere around the early Earth, which exhibited over long periods a deposition of rock-forming substances.

It goes without saying that here one can shake one’s head and begin immediately to place chemical and physical counter-arguments on the table.  Consider, however, with what ease the hypothesis of continental drift was earlier opposed:  It appeared physically impossible that continents could plow their way like icebreakers through kilometer-thick basaltic oceanic crust.  The phenomenon that Eurafrica could be placed like a puzzle-piece along the east coast of North and South America was ignored as being a coincidence.  Only later was it noticed that there was a small gap in the thought-structure- the continents did not plow through the basalt, but were carried along with it.  The thesis of continental drift proved to be correct, and has solved innumerable geologicl problems.  Such arguments can naturally not be used to defend any kind of theory, but the decades-long battle over continental drift can possibly lead to a more reflective consideration of certain phenomena.