My good friend Lee Covino recently sent me an article from ‘Science News’ (Vol. 161, no 12) about the source of Earth’s oceanic water (1).  Written by Ben Harder, the article outlined the latest scientific thinking about where all the water on Earth came from.  This is a particular problem for planetary scientists because the Earth simply should not have the amount of water that it does.  The Earth is relatively close to the Sun, and water, a volatile, should have been expelled from the early inner solar system before the Earth formed.  As such, the Earth should really be a much drier planet.  So where did all the water that is so crucial to the biosphere of this planet originate?

Ben Harder describes various theories that are currently doing the rounds in scientific circles.  Up until recently the leading theory was the notion that the oceans were deposited by comets impacting the newly formed Earth (the ‘late-veneer’ hypothesis) (2).  This bombardment occurred over a billion years (and might also explain how life appeared on Earth so early in its geo-history).  But according to Ben Harder’s article, recent data from comets has overturned this possibility.  The problem is that the isotopic ratios of terrestrial water and cometary ice are quite different.

The comets analysed thus far contain relatively large quantities of deuterium, yet this isotopic form of water is rare on Earth.  If this composition of known comet ice is representative of solar system comets in general, then very little of the Earth’s water can be attributed to cometary impact following the Earth’s formation. Taking this into account, it appears that only half of the Earth’s oceans could have been deposited by impacting comets.  As Ben Harder puts it:

“Assuming that the compositions of Halley, Hyakutake, and Hale-Bopp are representative of all comets, explaining how a hail of the objects could produce oceans with an earthly deuterium-to-hydrogen ratio is like trying to make a low-fat dessert from heavy cream.”

Puzzled scientists have tried to patch the flagging ‘late-veneer’ theory up, topping up the comet contribution with that of water-rich asteroids, but that doesn’t explain other problems to do with the Earth’s chemical composition.  The Earth is rich in many other volatiles, and these elements (mostly noble gases) are not noted on meteorites.  Topping up comet water deposition with that of water-rich asteroids would not explain the relative abundance of these other volatile chemicals.  For example, recent studies by scientists at the University of Arizona regarding the relative isotopic ratios of osmium in carbonaceous chondrites sink the late-veneer theory still further; the upper limit for deposition of volatiles from space after the Earth’s formation is a meagre 15% (3).

These new findings are causing planetary scientists a big headache.  The natural implication is that the Earth formed with its volatiles in place right from the start.  Yet current models of the primordial solar system rule this out.  Various new ideas are being floated, in varying degrees of complexity, to explain this contradiction.  Perhaps the primordial inner solar system was a cooler place than originally thought?  Perhaps the Earth was formed from a multiplicity of planetary ‘embryos’, some of which originated nearer Jupiter than the Earth, thus allowing a build up of indigenous volatiles?  Perhaps the rocks that formed the early Earth trapped massive quantities of water within them, preventing the volatiles from being routinely expunged from the inner accretion disc?

As those cheeky comic chappies from the spoof Japanese show ‘Banzai!’ would say: “Place your bets now!”

“Betting Ends!”

The solution is staring all of these planetary scientists in the face. It is so obvious that its absence within Ben Harder’s otherwise excellent article speaks volumes in itself.  The Earth has a rich mixture of volatiles, including water, because our planet originally formed much further away from the Sun.

But how much further?  Clues can be gleaned from the ‘embryo’ theory of the Frenchman Allessandro Morbidello (4).  He proposes that the Earth formed from the coalescence of Moon-sized embryos derived from various chaotic orbits in the primordial solar system. The ‘volatile carriers’ would have formed at about 4 Astronomical Units; four times further away from the Sun than the Earth, but still within the orbit of giant Jupiter.  He notes, however, that the water-bearing carrier from 4 AU would have been geo-chemically unique in the solar system.

Rather like the Earth itself, then?

The data about water isotope composition in the inner solar system strongly suggests that the Earth formed about 4 astronomical units away from the Sun. This, of course, does not ‘fit’ the standard model for the evolution of the solar system.  Yet the evidence points in this direction, so scientists should be reviewing the standard model.

If the Earth was once four times further away from the Sun than it is now, then we must explain how it managed to find itself in its current close proximity to the Sun.  Somehow, it was shunted into the inner solar system from an orbit originally much closer to that of Jupiter.

A model for this action already exists in the form of Zecharia Sitchin’s ‘12th Planet’ hypothesis (5).  Upon translating and interpreting ancient Sumerian cuneiform texts, this scholar proposed that the earliest Mesopotamian myths were describing the solar system to a high degree of accuracy, but with a few additional features.   Interpreting the myths in an astronomical context suggested to Sitchin that an undiscovered planet exists among the comets, one that was not an original member of the solar system, but an interloper wandering in inter-stellar space that blundered into the planetary zone.

There it encountered a watery world at about 4 Astronomical Units, and a great ‘celestial battle’ took place between these planetary ‘gods’.  The result was the shunting of this Water World, ‘Tiamat’, into the inner solar system, where it became the Earth.  The intruder, ‘Nibiru’, spun off into an eccentric orbit beyond the known planets, where it remains to be re-discovered to this day.

This is controversial material, of course.  Not the kind of speculative reasoning that readily appeals to the rational mindset of our academic brethren.  But the Water Conundrum we have just considered is remarkably consistent with this hypothesis.  Not wishing to rely too heavily upon that old die-hard ‘Occam’s Razor’, we seem to have a simple solution to a difficult problem.

The Origin of Earth

However, the isotopic evidence about the cometary ice would also call one of Sitchin’s own claims into question. He proposes that debris from the impact of the primordial Earth and Nibiru, and/or one or two of its moons, was scattered into the solar system forming the asteroid belt, and the comets.  Perhaps the formation of the asteroids may have occurred in this way, but not the comet.  The ‘late-veneer’ theory itself is in trouble because the Earth’s oceans could not have been wholly derived from comets.  So conversely the solar system’s comets could not have been formed from the oceans of the primordial Earth.  If they had then the comet ice isotope ratio would be consistent with that of Earth.

Current theories of the formation of the Moon are centred upon a massive collision between the early Earth and a Mars-sized body, scattering debris into orbit around the Earth, which eventually coalesced to form Luna (6).  The lack of a significant iron core within the Moon suggests that this impact took place after the Earth’s own iron core had already gravitated to the centre of our planet (7).  It’s conceivable that the remainder of the early Earth’s scattered debris formed the asteroid belt, given Sitchin’s proposal, and this possibility is readily testable by further scientific study of the composition of asteroids within the belt between Mars and Jupiter.  This might have occurred when the Moon formed, or as a result of later impacts upon the recovering Earth.

If correct, then the primordial Earth must have been a very significant planet indeed, such that major impacts upon it created both the asteroid belt and the Moon (but clearly not the comets).  Such a massive terrestrial planet could have readily held onto a vast amount of volatiles at the original distance of 4 astronomical units.  It also would not be so incongruous that the larger primordial Earth would have hosted such a massive satellite as our Moon, a point noted by Sitchin when describing the relationship between the Sumerian Tiamat and ‘Kingu’.

If the Moon came into being following a collision between the early Earth and a Mars-sized body, then how would that tally with the ‘celestial battle’ described in the Babylonian ‘Enuma Elish’?  The picture is complicated by the scientific discovery of the ‘late, great bombardment’ upon the Earth/Moon system 3.9 billion years ago (8).  Was this the Celestial Battle described by the ancient Mesopotamians?

Perhaps the very early Earth (Tiamat) was cracked originally open by a Mars-sized body, forming the Moon (Kingu).  Tiamat remained a giant watery world with a new, substantial Moon. And so they might have remained had the solar system not been disturbed by an interloper. 

Nibiru, a wandering giant planet or small brown dwarf (9,10), entered the planetary zone, bringing with it a ready made contingent of comets and moons.  This latter action may have been the ‘late, great bombardment’ that occurred 3.9 billion years ago, when thousands of killer impactors bombarded our planet.

Nibiru’s immense gravity, momentum and non-orbiting vector perturbed Tiamat and caused it to fall towards the Sun, attaining an irregular new orbit.  Over billions of years, the resultant Earth was shepherded by the Sun and Jupiter into a more stable orbit, becoming the rather odd world we now live on, with its over-sized Moon and excessive water content.  Nibiru itself became captured by the Sun, but remains loosely bound and possibly erratic still, a condition that prevents the known planets from harmonising their resonances.

Earth’s Special Character

One final point to note.  If the Earth should not be nearly as wet as it is, being so close to the Sun, then it is perfectly possible that the Earth is actually a rather special place.  Without the action of a passing intruder planet of vast proportions (and I consider Nibiru to be no less than a sub-brown dwarf), the Earth would be a much colder place than it is now.  More like ‘Snowball Earth’.  Life relies upon liquid water…would the current bio-diversity on this planet have arisen if Earth was still at 4 AU?  One suspects not.

If a newly forming planet is close to a star, like Earth is to the Sun, and thus warmed by it sufficiently to maintain liquid water later in its history, then these exact same conditions should preclude the inclusion of water on that world in the first place.  The presence of abundant liquid water on the cooled planet becomes a paradox, because heat and water do not appear to mix when terrestrial planets form.  So this paradoxical situation we currently find on Earth is solved either by considering the possibility that the Earth has moved significantly closer to the Sun since its formation, or by rethinking how planets form.

Whatever caused our world to have so much water so close to the Sun, it may be unusual, possibly even unique. The Earth’s abundance of liquid water may be very rare if the action of an intruder planet is required to explain its shunting into a closer inner orbit.  (Saying that, some of the extra-solar planets found so far have odd orbits; particularly gas giants that whizz around the parent stars at very close proximity (11).  Why was the constituent gas not blown away by the star before the planet formed?  Does this imply that planetary orbits can change radically, possibly as a result of outside interference?  More planets, please, Dr Marcy!)

Life around Cool Stars

A final thought.  We always assume that our average boring old Sun is the blue-print for other star systems that might harbour the conditions for life.  Perhaps this assumption is correct, and the search for Extra-Terrestrial Intelligence should remain targeted at similar stars to our own Sun.  But if Earth’s acquisition of abundant water is truly an anomaly given the local heat generated by our Sun upon its formation, then perhaps we should be looking for life on star systems whose primordial fires aren’t so hot.  After all, the spectrum of stellar characteristics does not begin with our own Sun.

Red, or dare I say, even brown dwarfs would have formed without the same water-purging enthusiasm as our own yellow star.  I wonder if that means that we should direct our attention to the less bright members of the celestial family; even those who remain hidden entirely.  These relatively cool stars might have allowed watery worlds to form more readily around them, and bombard them with less harmful radiation to boot. SETI may have been searching in the wrong place all this time.

Water Worlds

The concept of 'migration' of planets has becoming increasingly acceptable of late.  It was not so long ago that Tom van Flandern heavily criticised Zecharia Sitchin's '12th Planet Theory' on the basis that Earth could not have migrated into the inner solar system from the asteroid belt.  Van Flandern argued that Earth's orbit should still be highly elliptical if that was the case, and the orbit should still cross through the asteroid belt.  These arguments were sufficient to swing Alan Alford away from the idea of the existence of a substantial Planet X body (12).

But science has moved on in recent years, and is generally more open to new possibilities about Planet X (13).  This is partly because of discoveries about our own outer solar system, but also because of the data that has accumulated about extra-solar planets.  Many of these 'exoplanets' have anomalous orbits.  Some of them are orbiting their stars at very small distances, and are known as 'Hot Jupiters'.  These bizarre giant planets are too close to their stars to have formed where they currently lie (according to existing theoretical models of planet formation, anyway), so the concept of 'migration' is increasingly mooted to help planetary scientists sleep at night.  If such a model can be widely applied elsewhere, then surely it could have happened in our solar system too?  Possibly even to the Earth?

The science writer Andrew Pike recently described a possible new class of planets that sound remarkably similar to Tiamat, as described by Sitchin. This class of planets, called the 'Water Worlds', are still theoretical, but this looks like a very exciting development for those interested in Tiamat's transformation into the Earth:

“Alain Leger of the Institut d’Astrophysique Spatiale, France, has suggested a new class of exoplanet called a ‘Water World’.  Such worlds would be completely covered in water with no land masses.  They would have twice the diameter and around six times the mass of earth with orbital distances from their host star about the same as the Earth (1 AU).  They would have a metallic (probably iron) core about 4000 km radius, surrounded by a rocky mantle 3500kn thick, and be overlaid by a layer of ice 5000km thick covered by the liquid ocean 100km deep.

 “Finally, the planet would have a gas atmosphere to retain its liquid surface preventing evaporation into space.  Water Worlds would start life in a similar way to Uranus and Neptune in our solar system.  However, in these exosystems they might then migrate to the warmer inner regions heating up as they go.

 “Such migration is likely to be commonplace in exoplanetary systems. It explains a lot of features observed there, in particular how the Hot Jupiters formed.  These Water Worlds are still in the realms of speculation but there are a lot of reasons to believe they might exist and their detection might be closer than we think.  Should one of these Water Worlds pass in front of a Sun-like star it would cause a dimming in the star’s light of one in a thousand parts which is well within the scope of planned detection projects like the Eddington and Kepler missions [designed to widen the search for extra-solar planets].”  (14)

There is so much that we don't understand about the formation of planetary systems.  This can be only one of a myriad of possibilities, but its early introduction to scientific speculation would indicate its potential.  If such Water Worlds are found to exist then they would provide a huge lift for Sitchin's theories. Because one of them may have formed between Mars and Jupiter and, through interaction with Nibiru, migrated into towards the Sun 3.9 billion years ago, thereby losing substantial quantities of that water into the solar system.  The result, as they say, is history.  Earth's History!

Photosynthesis

Over the years I have described how an ecosystem might have arisen on a moon orbiting a small brown dwarf, whose light emission is minimal.  It can be easily argued that the conditions on that moon would be warm enough for liquid water, but some have offered a counter-argument that there still would be insufficient light for photosynthesis to take place in the outer solar system.  Such light as there is would have to come from Nibiru, an old and small sub-brown dwarf: a class of failed stars about which we have little knowledge.  Astronomers argue about whether such bodies can even emit light, but there does seem to be a good possibility that they do, through chemical reactions in the substantial outer layers of atmosphere.  This would result in 'flaring' of light rather than constant brightness.

This is rather like arguing for light-emitting fish in the Deep Sea oceans. Before their discovery no one would have expected 'Angler Fish' at the bottom of our oceans.  Is Nibiru the planetary equivalent of a neon red Angler Fish?  Is its moon system lit by this little oasis of red light in the deep abyss of the outer solar system?  I suggest that it is.

So would this be sufficient for photosynthesis to take place out there?  We can look to events on our own planet to answer that question, particularly under the Antarctic ice.  The scientist Chris McKay has studied eco-systems that depend upon the dimmest of light emerging through the ice to trigger photosynthesis:

"Only about 2 percent of the Sun's light gets through the ice and reaches the cyanobacteria, but that's plenty bright enough to support photosynthesis.  To McKay, in fact, the ability of some photosynthetic  organisms to survive in dim light carries an important lesson for exobiology "There are plants that photosynthesize at light levels equivalent to living at a hundred astronomical units" he says...[which] would extend more than twice as far as the Sun's most distant planet, Pluto.  Therefore, McKay believes, there is no reason to think that any of our Sun's planets, or similarly placed bodies around Sun-like stars, are too dimly lit to support photosynthetic life." (15)

When you add in the warming and local lighting effect of the dark star Nibiru, then conditions on its moons would be more favourable still for the emergence of complex ecosystems in the outer solar system.  Game on.

Equatorial Sea on Mars; Confirmed!

Regular readers of this website will have heard quite a lot about Dr John Murray down the years; he's an Earth Scientist at the Open University based in Milton Keynes in England.  One of his interests is astronomy, and he was of course one of the professors who put forward the idea of a brown dwarf in a great circular orbit around the Sun back in 1999.  He's been hard at work again, this time due to his involvement in ESA's Mars Express mission.  His geological knowledge has been put to the test with these images of ice floes on an equatorial region on Mars (16,17).

A press release by University College London (UCL) confirmed the finding after a recent presentation to ESA scientists at a conference in the Netherlands.  The imaging camera on Mars Express seems to have caught a sea frozen just 5 million years ago, then covered in volcanic dust, preventing the sublimation of the ice by Mars' frigid and thin atmosphere. The BBC carried the news this morning, highlighting the additional finding of methane gas over the same general area.  The combination of a deep body of water and methane gas is strongly suggestive of life existing presently under the Martian surface. 

The sea itself is about the size of the North Sea off the east coast of the United Kingdom, and has an average depth of about 150 feet.  It is located in the area of Mars known as Elysium, 5 degrees north of the equator.