The Earth Was A Super-Earth From Another Solar System And Maybe Another Galaxy Our beloved blue-green cloud covered speck of cosmic dust, also known as Earth, may be a remnant from another solar system; a rogue planet which was ejected from a dying solar system prior to supernova-- a theory first proposed by R. Joseph, and then endorsed by Rudolf Schild of the Harvard-Smithsonian, department of astrophysics. It is believed there are billions of rogue planets careering through space in the Milky Way galaxy alone; and like all extra-solar planets so far discovered, these rogue worlds may be super planets, several times the size of Earth, Saturn, and Jupiter.
If Earth had gone rogue, it may well have started its journey as a planet several times larger than the Earth of today, having been whittled down in size after taking up residence in this solar system; one big chunk of which, our moon, having been ripped away perhaps 4 billion years ago. Moreover, not just Earth, but this solar system, may have gone rogue after being torn from the Sagittarius dwarf galaxy, which orbits the Milky Way.
If Earth, this sun, and our solar system began as rogues, this may explain why the Milky Way appears at an angle in the night sky. If formed as theorized by the standard model of accretion and nebular cloud formation, then, when viewed from Earth, the Milky Way should be oriented to the galaxy's ecliptic, with the planets aligned around our Sun in much the same angle as our Sun aligns with the Milky Way. Instead, our Sun and solar system are organized at a very strange angle; observations which suggest that our entire solar system may have originated elsewhere and have not yet stabilized as the galactic tug of war is still ongoing.
Common wisdom is that planets grow by accretion after collisions with other moon- and planet-sized stellar objects. However, this view is not supported by physics. Two objects do not grow larger when they collide. They shatter and grow smaller--which is how our moon is believed to have been formed after Earth collided with another rogue planet.
Super-Earth, super Jupiters and super Saturns are common in the narrow stretch of this galaxy so far surveyed. Super planets appear to be the norm, at least in this corner of the cosmos. As argued by Joseph and Schild, all planets may begin as super planets and then grow smaller after colliding with other worlds. As is well established, early in its history, this solar system was a massive cosmic shooting gallery with all sorts of planets colliding into one another.
For example, around 4 billion years ago, a Mars-sized planet may have hit the Earth with so much force that the ejected mass may have come to form the moon. Around 4 billion years ago, the northern plains of Mars was gutted by a planet-sized body which left an elliptical depression 6,600 miles long and 4,000 miles wide. The planet Mercury may have also suffered a collision which left a titanic impact basin. Uranus was apparently struck so hard by a super-sized planetary body that its rotation axis tilted sideways, nearly into the plane of its revolution about the Sun.
That planet-sized objects were careening through the solar system during its early stages of formation and in directions and trajectories different from the other planets is not consistent with the accretion model of planetary formation--a model which is defied by common experience (just toss two rocks at each other) and basic physics: stellar objects growing smaller, not larger, following collisions.
And where did all these wayward planets come from? Every planet, and almost every moon, in this solar system, may have originated in another solar system, or even another galaxy. There is no way so many wayward planets could have formed by accretion in a protoplanetary disc; as no planet forms by accretion, and all planets should have had the same orbit. Instead, the evidence is of super rogue planets careening in every conceivable direction, and crashing into each other, growing smaller in the process, until finally the solar system stabilized with some rogue planets becoming moons orbiting Jupiter and Saturn.
Joseph and Shield propose, that instead of accretion, where tiny rocks somehow crash together and grow larger instead of shattering apart, all the planets and moons in this solar system may have originated in a neighboring solar system and were ejected when the parent star began to die and began the Red Giant stage of its death throes. That dying solar system, however, may not have been a member of this galaxy, but the Sagittarius dwarf galaxy, which intersects, like a bull's eye, the Milky Way in the exact position occupied by our sun.
Rogue Planets From A Dying Solar System: Red Giants and Expulsion
According to the model developed by Joseph and endorsed by Schild of the Harvard-Smithsonian, Earth was originally a super-Earth, perhaps several times larger than its present size. When the parent star became a red giant, the accelerating power of its solar winds would have blown away the life-sustaining atmospheres of its planets which included airborne microbes, creating a nebular cloud at the far edges of the dying solar system. However, as it became a Red Giant, it would not have destroyed all orbiting planets.
Specifically, as a star enters the Red Giant phase, it loses mass, and in consequence, its planets would have significantly increased their orbital distances from that dying sun. Estimates are that a Red Giant may lose anywhere from 40% to 80% of its mass before exploding---however, prior to super-nova, its orbiting planets would continue to increase their orbital distances, with most being ejected hundreds of millions of years prior to supernova. It is these ejected planets which go rogue, and if captured by the gravity of another solar system, some would crash into each other, growing smaller in the process. Earth and its moon, are an excellent example of a planet growing smaller after a cosmic collision--when the moon was ejected from Earth, following a collision, Earth grew smaller. In fact, the Earth was bombarded by moon-sized cosmic debris for almost 800 million years--and much of that debris appears to have also originated as ejecta from a parent star which became a Red Giant then exploded in a super nova.
Going Rogue: Expulsion From a Parent Star - Evidence from the Murchison
The parent star for our Earth was probably not our sun--and both the parent star, and our sun, may have originated in another galaxy. That the parent star died and underwent super nova before casting out Earth which went rogue, is is supported by isotopic analysis of the Murchison meteorite.
As reviewed by Joseph, measurements of silicon carbide from the Murchison indicates that the grains and silicon are most likely the residue of or were produced secondary to a supernova. Supernova also impacted a number of other carbonaceous chondrites, including the Orgueil, Allende, Efremovka, and Ivuna meteors. A detailed analysis of ubiquitous of FE and NI carbides in the rims of magnetite and the carbide grains within the Murchison also indicates oxidation within the parent body of the meteor, which could have been a much larger body such as a planet or planetesimal. An analysis of the presolar SiC grains and other isotopes, indicates the Murchison meteor was impacted by the supernova of a carbon rich intermediate mass star that was between 1.5 to 3 solar masses. Thus, the Murchison and the other carbonaceous chondrites impacted by supernova, may be a remnant of a planet which was ejected or shattered when the parent star finally exploded.
The kinetic energy of an orbiting planet is half the energy of its escape velocity. Planets as well as the central star exert gravitational effects on one another. A star loses from 40% to 80% of its mass during the red giant phase. Therefore its gravitational influences would be lessened. Thus, planets that had occupied an Earth-like habitable zone would have begun to increase their distance from the parent star as it lost mass and expanded in size. If these planets were larger than the Earth (and depending on other parameters) they would likely be expelled from the solar system prior to supernova.
Consider again the Murchison. An analysis of the isotopic composition of silicon carbide grains, indicates impact by shock waves from a supernova of a star which has lost almost all of its hydrogen mass, indicating its gravitational influences were significantly reduced. These findings, coupled with results from shock-recovery experiments performed on insoluble organic matter within the Murchison are also consistent with the proposal that the Murchison is a remnant blasted from its planetary body which was expelled from the solar system prior to supernova, and was then impacted following supernova, perhaps while drifting within a planetary nebula.
If Joseph and Schild's theory is correct, this would explain why numerous rogue super planets have been discovered; all of which may have been ejected from dying solar systems. This would explain why full formed planets were already crashing into each other during and soon after the formation of this solar system. It is believed that Earth was struck by a Mars-sized planet within 30 million years after the formation of the solar system,
Could Rogue Planets Harbor Life?
Could human life have evolved on the super-Earth before going rogue? Joseph and Schild estimate that the parent star for the original super-Earth may have been around 3 billion years in age before it entered the red giant phase. Using the Earth as an example, this is enough time for microbial life to flourish but not enough time for complex life forms to evolve. On the other hand, it may be possible for some rogue planets drifting in the vast expanses of cold interstellar space to sustain a thick freeze-resistant hydrogen atmosphere--and then there is the possibility that complex creatures may dwell deep beneath the frozen surface of rogue water worlds, such as Europa; and if so, such creatures could continue to thrive if not evolve.
Did Earth and Our Solar System Originate in the Sagittarius Dwarf Galaxy?
It is well documented that not just planets, but that solar systems also collide and exchange planets. Yet another possibility is that planets are expelled during the standard model of solar system formation. Another likelihood is that planets and stars numbering in the billions may go rogue and are exchanged when galaxies collide, or intersect.
The Milky Way is orbited by several dwarf galaxies; but one in particular, the Sagittarius dwarf galaxy, intersects the Milky Way in the exact location occupied by this solar system. Given the Milk Way's massive (relative) size compared to Sagittarius which is 10,000 times smaller, it appears that with each orbit, the Sagittarius dwarf galaxy is stripped of stars and planets. Evidence for this possibility is considerable, some of which has been published in the Astrophysical Journal by Steven Majewski and colleagues.
The Milky Way galaxy has been engaged in an ongoing feast of galactic cannibalism for at least 10 billion years; and stars, planets, and other stellar debris wraps around and intersects this galaxy. Our solar system is located at the nexus, and with each orbit, the Sagittarius galaxy gross smaller in size as it is stretched out, ripped apart and gobbled up by the bigger Milky Way.
"If people had infrared-sensitive eyes, the entrails of Sagittarius would be a prominent fixture sweeping across our sky," said Steven Majewski, the lead author. "But the evidence become buried among countless intervening stars and obscuring dust. The great expanse of the Sagittarius system has been hidden from view."
However, by using infrared maps, the astronomers filtered and were able to remove millions of foreground stars so as to focus on large, infrared-bright stars, which are populous in the Sagittarius galaxy but uncommon in the outer Milky Way.
"We sifted several thousand interesting stars from a catalog of half a billion," said co-author Michael Skrutskie. "By tuning our maps of the sky to the 'right' kind of star, the Sagittarius system jumped into view." And then, it became apparent, that remnants of Sagittarius were piercing the Milky Way and intersecting the orbit of our sun.
Certainly, the gravitational pull of the Milky Way which is 10,000 times larger, could rip away Sagittarian stars and planets. Could these titanic tidal forces also trigger super novas in those stars losing mass as they are torn away when galaxies collide? This is unknown.
If Earth, and our sun, are rogues, this could explain why the Milky Way appears at an angle in the night sky. If we originated in the Milky Way then our solar system should be oriented to the galaxy's ecliptic, with the planets aligned around our Sun in much the same angle as our Sun aligns with the Milky Way. Earth and this solar system are disoriented. This suggests that the momentum and forces responsible for ripping our planet from another galaxy have not yet been stabilized by the gravitational influences of the Milky Way. In other words: we have not yet completely escaped the gravitational influences of the tug of war between the Milky Way and Sagittarius Dwarf galaxy and are still in the process of joining the Milky Way which is not our parent galaxy.
Earth, and our sun, are rogues.
References
Cartwright, J. (2011). Homeless' Planets May Be Common in Our Galaxy Science, May 18. 2011
Joseph, R. (2009). Life on Earth Came From Other Planets. Journal of Cosmology, 1, 1-56.
Joseph R. Schild, R. (2010). Biological Cosmology and the Origins of Life in the Universe. Journal of Cosmology, 5, 1040-1090.
Majewski, S. R., Skrutskie, M. F., et al. (2003) A Two Micron All Sky Survey View of the Sagittarius Dwarf Galaxy. I. Morphology of the Sagittarius Core and Tidal Arms, The Astrophysical Journal, 599, 1082-1115.
