Did the solar system begin naturally or supernaturally? Since science cannot investigate the supernatural per se, the best way to address this question is to investigate the possibility of a natural origin. If a natural explanation cannot be found, that negative result becomes evidence of a supernatural origin – provided, of course, that enough facts exist on which to base a judgement, as is surely the case now.
Suppose that everything began with an act of creation. Would we be able to deduce that that was how things began? Conceivably, a scientist might retrace the long chain of causes back from the present all the way to the moment of creation and not know when he had arrived, unwittingly continuing to go back into a past that never existed. The solar system would be like a drama beginning in medias res. This was the problem that troubled the 19th-century naturalist Philip Gosse: the unavoidability of creating things with apparent age. It seemed to inhere in the very notion of creation.
But the problem is misconceived. Creation in the fullest sense implies bringing into existence that which cannot of itself come into existence and therefore cannot be construed as having had a natural origin. It takes place at the point beyond which the chain of causation cannot be pushed further. Consequently, anything that appears to have a history should be accepted as having a history. That the solar system had a supernatural origin should be neither ruled out nor assumed; instead, we test for the possibility by exhaustively exploring the opposite presumption. Since Genesis says that it was created, those who believe in the authority of that text must stake everything on the prediction that naturalistic attempts to explain its origin will fail.
It might be argued that science and theology are complementary, with the creation account simply revealing those things which we cannot discover by human reason. But human reason recognises no limits. Philosophy, including natural philosophy or what we is now termed science (meaning ‘knowledge’, a step up from philosophy), is the practice of asking fundamental questions independently of authority, and the presumption is that the solar system formed unaided; otherwise, reason, it is feared, would have no role to play. For want of any gradualistic alternative, naturalism entails some version of the nebula hypothesis, the gradual emergence of form from a state of chaos. Thus already in the 17th century René Descartes proposed that the Sun and planets condensed from a contracting vortex of particles. In the 18th Immanuel Kant – another renowned philosopher – proposed a cloud of aggregating particles, and around the turn of the century Pierre-Simon Laplace enhanced the credibility of the concept by fusing it with celestial mechanics. Laplace claimed to be able to account for the motions of the planets without having to postulate that the Creator periodically intervened to restore order. As he famously said to Bonaparte, “I have no need of that hypothesis.” Scientific explanations of phenomena had to be based on the laws and properties of nature.
Yet astrophysics is never entirely divorced from metaphysics. God as Creator is excluded not merely because science must consider natural explanations first, but de rigeur. NASA scientists believe that they might find unintelligent life on Mars or Jupiter’s moon Europa, because ‘life’ for them is merely atoms (and because hyping up the possibility helps get funding). The idea does not therefore rank as a superstition. Kant thought that Jupiter and Saturn might be inhabited by creatures more intelligent than human beings. More presciently he postulated that the tiny ‘nebulae’ observable through telescopes were ‘systems of many stars’, galaxies much like the Milky Way.
Despite the vast amount of information gathered about the solar system in recent decades, the basic picture of how it began remains unchanged. Initially there was a rotating molecular cloud of dust and gas. The ‘dust’ was a mixture of silicates, hydrocarbons and ices, the gas mostly hydrogen and helium. Over time collisions averaged out the vertical motions and flattened the particles into a disc. As gravity drew matter inwards, most of the cloud condensed into a central orb. Gravitational energy turned into heat, intense enough eventually for nuclear fusion to be initiated. In the disc other matter clumped into progressively larger units, eventually amalgamating to form planets.
The planets are divided into three types according to composition: the rocky or terrestrial planets Mercury, Venus, Earth and Mars, the mainly gaseous planets Jupiter and Saturn, and the so-called icy planets Uranus and Neptune. In fact, because temperature increases with pressure, the hydrogen and hydrogen compounds of the latter two consist mostly of hot, dense fluids (Helled & Fortney 2020). They also, like Jupiter and Saturn, contain large amounts of rock.
The rock-gas-ice sequence of the planets is attributed to the disc’s temperature gradient. Close to the Sun, where it was warmer, refractory elements condensed out before volatiles and solar winds drove the gas away, so that there only rocky bodies could form. They ceased to grow when there were no more smaller bodies in their orbital neighbourhoods to amalgamate with them. The Earth-Moon system reached its present mass in about 100 million years, maybe 40 million. Asteroids, perceived as leftovers of planet formation, continued to pockmark Mercury, Mars and the Moon for considerably longer. The formation of the gas and ice giants took place in two stages: first the accretion of rocky planetesimals, then gravitational condensation of gases around them.
Beyond Neptune is the Kuiper Belt, a region of small diffuse bodies with stable orbits between 30 and 55 AU from the Sun. The Kuiper Belt was only discovered in 1992 but is a major component of the solar system. Pluto, its most famous member, was discovered in 1930. In 2006 it was demoted to dwarf planet status, since its diameter was only two thirds that of Earth’s Moon and its gravity too weak to clear its orbital neighbourhood of other large bodies. That same year the New Horizons probe was launched to take a closer look. It reached Pluto in 2015, determining its composition to be about one third water ice and two thirds rock. Temperature at the surface is -220°. In view of its small size and remoteness, Pluto was believed to have lost its heat shortly after formation. Modelling, however, indicates that 40 to 80 km beneath the surface the water is saline liquid (McGovern & Nguyen 2024).
Asteroids (‘star-like’ bodies, from the Greek word aster) are scattered all over the solar system. The main asteroid belt (so called) lies between Mars and Jupiter, with those above 1 km numbering at least a million. Near-Earth asteroids orbit between Mars and Venus and are smaller on average, having drifted over from the main belt. Those above 140 m in diameter number more than 10,000; at least 900 exceed 1 km. There are also irregularly orbiting asteroids called centaurs between Jupiter and Neptune and countless TNOs between Neptune and the edge of the solar system. A few of the centaurs and some of Neptune’s moons may have been disturbed from orbits originally in the Kuiper Belt. Over time some drifted further across towards Jupiter. This is the explanation for the arrival of comets in the inner part of the solar system: they are ‘Trans-Neptunian Objects’ (TNOs) drawn in from the Kuiper Belt and from the poorly known Scattered Disc beyond that. ‘Disc’ is a misnomer, since many of the orbits are scattered at high angles to the ecliptic. The two regions overlap, and enclose a space far greater than that containing the planets.
Asteroids, it is thought, were prevented from gaining further mass because, beyond about 2 AU (twice Earth’s distance from the Sun), there simply wasn’t much rocky material. If we assume that the overall density in that region was the same as needed to produce the planets elsewhere, we can estimate how much material there was (Bottke et al. 2005).
Estimates can be made using the assumption that the nebula contained just enough material of solar composition to form the planets at their current locations and compositions. These model results suggest that the Solar System’s surface density may have varied as r-1 to r-3/2 between Venus and Neptune, where r is heliocentric distance [distance from the Sun].
That is, according to these two-dimensional models, the density of the particles would have declined exponentially with distance, i.e. steeply close to the Sun and less steeply further away.
Compared to this prediction, however, the amount of solid material in the main [asteroid] belt zone today is nearly 1000 times lower than our expectations. This is a serious problem.
The belt’s mass has since been revised downward to less than 1/2000th that of the Earth (Morbidelli et al. 2015), doubling the amount missing. Also, many of the asteroids must have drifted in from the outer solar system, so the original number would have been considerably smaller. On the other hand, the rate at which meteoroid-sized objects hit Mars’s surface is five times greater than thought, so the estimate of the belt’s present mass may need to be revised upward again, though not by much (Zenhäusern et al. 2024). A similar ‘missing mass problem’ concerns the Kuiper Belt. In particular, the original number of Pluto-size objects is believed to have been 1,000-4,000 more than now.
Thus explanations have to be found for (i) why the objects in these regions failed to accrete, despite having a total mass 500–2000 times greater than now, and (ii) how more than 99% of their present mass might subsequently have been lost. Almost from the start, asteroids and TNOs have generally been getting smaller and smaller, not larger and larger, as a result of colliding with each other and grinding each other down (Stern & Colwell 1997).
That there are no rocky planets nearer the Sun than Mercury shows that planet formation was not inevitable. If the solar system formed in the same way as planets elsewhere in the Galaxy (as will be discussed), there should have been at least one. But perhaps the greater mystery is why there any, for the same collisional erosion observed to be limiting asteroid growth between Mars and Jupiter should have inhibited accretion, albeit that is not what models suggest. Some end up with a Mars much bigger than the real one, plus addi¬tional Mars-sized embryos in the asteroid belt (Izidoro et al. 2015, Tsiganis 2015). Such embryos are, however, fictional.
Earth, the most massive of the four rocky planets, is almost 10 times Mars’s mass, Mars many times more massive than the asteroid belt. If we ignore Mercury and Venus, this sequence of three conforms to the expected trend of decreasing rocky material with distance. Next is Jupiter, the nearest gas giant. With a mass and gravitational force greater than all the other planets put together, it would have drawn away and ingested much of whatever rocky matter once occupied the belt region, perhaps even an entire Earth’s worth. Very surprisingly, however, Jupiter’s rocky core amounts to 10–30 Earth masses (Miguel et al. 2022). Moreover, it is diffusely distributed, not all concentrated in a core.
Saturn, next along, is as distant from Jupiter as Jupiter is from Mercury, and its mass over three times smaller than Jupiter’s. Yet its rock component is about the same as Jupiter’s, around 15–18 Earth masses (Iess et al. 2019), and proportionally three times greater. That the rock buried within the gas giants is diffuse is also problematic. Before the results of the Juno space probe came in, astronomers had calculated that the planets had either a very small, dense core or no core at all.
Uranus and Neptune are much smaller than Jupiter and Saturn but also challenging to explain (Helled et al. 2020). A wide range of models of their interiors can account for their observed properties, from ice-dominated to rock-dominated. Their atmospheres are mostly hydrogen and helium, which suggests that a substantial proportion also consists of these elements. Whatever the case, at 19–30 AU, the disc would have been too thin; they would have taken longer – more than 10 million years – than the disc supplying the material could have been in existence. Some modellers therefore conjecture that they formed much nearer the sun and migrated outwards, possibly swapping places in the process.
The simplest solution to these problems is that the rocky material came from planets that exploded, at a time when the giants consisted solely of gas – Uranus’s material mostly from a neighbouring planet nearer the Sun, Neptune’s from a more distant planet. The distance between the Sun and Mars is less than half that between Mars and Jupiter, so there was certainly space for another planet after Mars. An explosion in that region would explain why the orbits of some asteroids – fragments that did not get sucked in by Jupiter’s enormous gravity – are eccentric and at high inclinations. Saturn, similarly, might have acquired its rock from an explosion between it and Uranus, giving rise to the asteroids in that part of the solar system. (A planet 25 times Earth’s mass may sound enormous, but its diameter would have been just 3 times greater, and Jupiter would still have been many times more massive.)
The rocky Kuiper Belt objects, among them the dwarf planets Pluto and Haumea, might be the remains of a third exploded planet. One of the peculiarities of these objects is that their orbits are both more inclined and more elliptical than those of the major planets. Some even orbit in the opposite direction. In the words of Bernstein et al. (2004), ‘the TNO population only vaguely resembles the preconception of a dynamically pristine planetesimal disk.’ The poorly known Scattered Disc might be the remains of a fourth exploded planet. Its largest member is Eris, about the same size as Pluto but rockier (around 90%); its orbit is highly inclined and highly elliptical. That would make 8 surviving planets and 4 shattered ones, the same number as in Joseph’s dream.
Another difficulty with the core accretion model (where rocky cores accrete first, then gas around them) is that the same spiralling in of matter that formed the Sun would also have drawn in the growing planetesimals. As has long been known, frictional and gravitational interaction between the gaseous disc and the rocky planetesimals would have caused the latter to migrate inward, and the time involved, about 100,000 years, is much shorter than that needed to produce the giant gas planets. The growing planets would have plunged into the Sun before they could reach their present size (Cresswell & Nelson 2006).
The problem is particularly acute for smaller bodies, from 10 cm diameter to a few metres. Solid particles in the nebula orbit at speeds substantially greater than the surrounding gas. As they move through it, they become subject to a head wind, lose their energy to gas drag and drift inwards. At one Earth-distance from the Sun the rate of migration is of the order of only 100 years (Armitage 2007). On average, particles that reach metre size have not much more than 1,000 years to make the leap to planetesimal size, above 1 km, when gas drag ceases to be a factor. Once the Sun approaches its maximum mass, thermonuclear fusion generates a strong stellar wind which clears the inner solar system of gas and dust.
Experiments, including those performed on the International Space Station, show that millimetre-size particles will spontaneously coalesce into loosely bound 1–5 centimetre clumps, and growth can be modelled up to metre size. Sticking is promoted by electrostatic forces, also by frost if present. Beyond 1 metre, aggregation can be frustrated by even a small amount of turbulence as collision effects turn from sticking to bouncing or even disaggregation. Gravity becomes an appreciable force only beyond 1 km diameter. Because of this ‘metre-size barrier’ the process leading to the formation of planetesimals is ‘somewhat murky’ (Armitage 2007). This is not to say that larger-scale aggregation could not have happened. It is clear from the low-density asteroids known as ‘rubble piles’ that it did. Nearly all asteroids from 200 m to 10 km in size are rubble piles. While their bouldery material consists of collision debris and therefore does not support the nebula idea, they at least give evidence of secondary aggregation. One example is Sylvia, a lumpy potato-shaped asteroid 380 km across. Another is tiny Dinkinesh, 790 metres across. On the other hand, gravity does not automatically bind asteroids together, for both Sylvia and Dinkinesh have satellites. Mars’s tiny satellite Phobos is also a rubble pile.
Once bodies reach 100 km, the currently favoured explanation for how they form is accretion by pebbles (Johansen et al 2015). A persistent problem is that some meteorites contain millimetre-sized condensates termed CAIs and chondrules. Dating studies suggest that CAIs existed separately in the nebula for up to 3 million years before accreting with chondrules and other constituents to form larger particles. Such a long delay is ‘incompatible with dynamical lifetimes of small particles in the nebula and short timescales for the formation of planetesimals’ (Weidenschilling et al. 1998). Moreover, pebble accretion should result in the largest rocky planets forming closest to the Sun and the smallest forming beyond Saturn (Morbidelli & Raymond 2016), whereas the gas giants each have more rock than all the terrestrial planets put together.
When Galileo in 1610 peered at Jupiter through his telescope, he was amazed to see four previously invisible satellites. Not only was the Earth’s position in the solar system not unique, but the Moon was not the only moon. In fact, around the giant planets we now know of more than 200. Those with comparatively tight, circular, equatorial orbits are classified as regular satellites. Although diverse, most are believed to have formed in the same general region as their host. The largest – Titan and Ganymede – are larger than present-day Mercury, albeit not as massive. The orbits of the irregular satellites are more elliptical and more inclined. They are thought to have originated elsewhere in the disc and later been captured. Some may be products of a collision that shattered a larger moon. Mercury and Venus, the planets closest to the Sun, have no moons. Earth has one, Mars two (both irregular), Jupiter 8 regular and, at the last count, 84 irregular, Saturn 24 regular and 121 irregular, Uranus 18 regular and 10 irregular, Neptune 7 regular and 9 irregular. Many of the more recently detected moons are less than 3 km across. Unlike their hosts, the largest moons are predominantly rocky, the rest entirely rocky.
Genesis does not explicitly say anything about what is not visible to the naked eye. It focuses on the solar system, the space delimited by the enclosing envelope of water. While the modern reader assumes that the ‘stars’ were the stars of the Milky Way, that is poor exegesis, and other parts of the Bible show that the Hebrews believed the heavens to be bipartite, consisting of a ‘firmament’ and a much bigger heaven beyond the firmament (Deut 10:14, I Ki 8:27, Ps 148:4). They would therefore have perceived well enough that the stars of the firmament were the wandering stars. When Nehemiah summarised what God did at creation, he proclaimed, “You made the heavens, the heaven of heavens and all their host, the earth and everything on it, the seas and everything in them” – the solar system, the universe beyond, and the Earth. The host of the numberless ‘stars of the heaven’ – including the primordial quasars – lay in the heaven above the firmament.
Accordingly, while creation theory predicts that the origin of the Earth’s moon will not yield to a natural explanation, it makes no predictions about other moons. We may readily infer that these are all primordial. Spherical shape is not itself a sign of creation, since gravity will of itself cause a body to assume a spherical shape above a certain mass. In any case most of them are small and have irregular shapes. Like the diffuse rocky material within the planets that host them, they must be the remains of planets that exploded.
The diversity of the solar system’s moons is well illustrated by the four that Galileo saw around Jupiter(Fig. 28). Their greater rockiness in order of closeness to their gaseous host is evidence against their having originated in the same process as the planet. Io, the densest and innermost of the four, has a substantial iron core and a solid, mountainous crust. Tidal stresses produced by Jupiter’s gravity and the opposite pull of the moons further out cause Io to be volcanically active, inducing the eruption of sulphurous gases and magma so voluminous that the moon has been completely resurfaced. Europa’s surface is frozen water, criss-crossed by dark streaks, beneath which tidal flexing maintains an ocean up to 100 km thick. Scientists who believe in spontaneous generation, a popular idea before Louis Pasteur knocked it on the head(in 1859, the same year as Darwin published his version of it), speculate that there could be life in this water. Ganymede is the largest moon in the solar system, larger even than Mercury, and has an icy shell 800 km thick. The surface is a patchwork of highly cratered dark regions and much younger lighter ones marked by grooves and ridges. Beneath the shell is a rocky mantle and a small, partially molten core, that generates a magnetic field. Callisto, the outermost and least dense of the four, consists of about 40% ice and 60% rock. It is among the most heavily cratered satellites in the solar system – evidence, as with Ganymede, that it is very old.
Apart from Mars’s two tiny moons, the only terrestrial planet to possess a moon is the Earth, in relation to which the Moon’s mass is exceptionally big. According to Genesis, it was created in order to divide the year into months and alleviate night’s darkness. Unstated purposes would have included the stabilisation of the Earth’s axial tilt and the production of tides. (Weaker tides would still occur as a consequence of the Sun’s gravity.)
The present Moon is far from pristine. The upper crust consists of a feldspar-rich rock known as anorthosite, its mineralogy and texture showing that it crystallised out of magma. The crystalline state implies an earlier molten state, so cosmologists are not being unreasonable when they deduce that the anorthosite must have crystallised from a ‘magma ocean’, though the scenario is open to challenge (Niu & O’Hara 2015, Torcivia & O’Neal 2022). As the interior melted, minerals separated out according to density, with those richer in iron sinking towards the centre. The upper crust is therefore iron-depleted. Enormous craters show that the Moon subsequently suffered bombardment by asteroids. In the wake of the impacts, upwelling basalt filled the craters and produced the smooth dark maria that blotch the surface. The indistinct rims of the oldest craters suggest that the crust was hot and still plastic when the first asteroids fell (Kamata et al. 2015, Conrad et al. 2018). None of the rocks sampled by the Apollo missions go back to the Creation, so the Moon’s origin cannot be investigated directly.
Aggregation from the same part of the nebula as the Earth came from may be discounted, because the Moon has a smaller proportion of volatiles and iron and is 40% less dense. The leading idea since 1984 has been that the Earth collided with a smaller planet of different composition which disintegrated and partly vaporised. Most of the debris from which the Moon then emerged came from the impactor. One difficulty is that the debris would have settled into an encircling disc aligned with the Earth’s equator, whereas the Moon’s orbit is currently at 5° to the equator and calculated to have originally been at 10° (Pahlevan & Morbidelli 2015). Claims to have solved the ‘lunar inclination problem’ have repeatedly been made and as frequently rejected. Only when another solution is proposed do the deficiencies of the previous one get pointed out.
The impact scenario also predicts that the Earth and the Moon will differ isotopically, since planets generally do. In fact their isotopic signatures are remarkably similar. Discussing the problem in 2013, Linda Elkins-Tanton reported that the Giant Impact Hypothesis was in crisis and would require ‘creative thinkers’ to make it plausible. Then came the proposal that the Moon formed from a succession of smaller impacts (Rufu et al. 2017), or that it formed from a planet that collided with the Earth without disintegrating into dust and vapour (Kegerreis et al. 2022). Neither of these variations addressed the compositional problem. Or perhaps the giant impactor was isotopically similar to the Earth (Dauphas 2017) and one just has to accept that this is statistically unlikely. ‘Identical … isotope compositions of the lunar and terrestrial mantles strongly suggest the two bodies were made from the same material, rather than from an Earth-like impactor’ – or that there was no impactor (Sossi et al. 2024). While one can never say never, as things stand the Moon’s ongoing resistance to natural explanations amounts to evidence that the satellite did not have a natural origin, though the search goes on.
Dates for the hypothesised Moon-forming impact – which cannot be dated directly – likewise vary. Most modeling studies put the event no later than 4.50 Ga. One recent estimate puts it around 4.4 Ga (Connelly et al. 2022). A magma ocean might have been a product of the impact, but how long the magma would have taken to solidify is also unclear. Most of the crust may have solidified in as little as a thousand years (Elkins-Tanton et al. 2011).
Undoubtedly the most significant development in the last three decades has been the observation of planets orbiting other stars in our galaxy. Discs have also been observed. A spectacular example is the one around PDS 70, a young star somewhat smaller and cooler than the Sun and one of only a handful of discs hosting distinguishable protoplanets. The disc partly consists of gas (Facchini et al. 2021) and partly of dust, including silicates, the raw material of rock. Between the star and the disc is a glowing and apparently still growing body, about the same distance from the star as Uranus is from ours, and seven times the mass of Jupiter. Another, about the same distance as Neptune, is three times the mass of Jupiter. Beyond them both is an asymmetric ring of dust. A thin inner ring can also be seen within 18 AU of the star (1 AU = distance from Sun to Earth), consisting of dust and water vapour.
At first sight such observations provide a great boost for the nebula hypothesis. It now seems likely that most stars have planets, and that in the early stages they are surrounded by rotating clouds of dust and gas. However, creation does not exclude the subsequent natural formation of planets any more than it does stars, so their discovery is neutral as regards whether our own solar system has a natural origin. Nor should we assume that the other systems formed incrementally. To suppose that the gap between PDS 70 and the main ring was caused by the two planets’ sucking up disc material as they grew is an interpretation and questionable for several reasons. First, according to mass/volume calculations the planets are less dense than Jupiter, despite being up to seven times bigger, so contain very little rock, and cannot have acquired their volatiles through accretion onto a rocky core. Second, relative to their mass and to the width of their orbits the gap is disproportionate. Planets have rarely been observed within discs consisting of rings and gaps; possibly the gaps are not the result of planet formation and possibly planets do not form by accretion. Third, according to the nebula hypothesis, discs should thin out with distance and become less dusty, whereas the PDS 70 disc is thickest at 80–140 AU; this is more than twice Pluto’s heliocentric distance. And lastly, the disc or ring may not be the remains of a star-forming nebula at all but a product of the star. A bridging stream (happening to envelop the further planet when the image was captured) extends from the star in opposite directions across the gap, as if the star itself were the source of the ring.
Jets and outflows around proto-stars are ubiquitous. They seem to be the source of the discs, rather than stars and planets both emerging from them (Lebreuilly et al. 2024). Just as with galaxies, some outflows result in rings, others in a spiral structure (Ginski et al. 2024), just as with galaxies. In cases where the proto-stars are binaries – two stars in orbit about each other – a disc can surround them both, showing that the stars predate the disc’s formation.
Exoplanetary systems can be classified into four groups: ‘similar’, ‘ordered’, ‘anti-ordered’ and ‘mixed’ (Mishra et al. 2023). In similar systems (the majority) the planets are of similar size and mass; in ordered systems planetary mass tends to increase with distance, and vice versa with anti-ordered systems. In most cases there is only one planet. The highest number observed is eight, around the star Kepler-90: six rocky inner planets, all bigger than Earth, followed by two gas giants. All eight lie well within the ‘snow-line’ at 1.1 AU within which the temperature should prevent gas giants from forming by condensation. One star, the red dwarf TRAPPIST-1, has seven planets. All are rocky, all less dense than the Earth and all within 0.07 AU of their star – also not an analogue for our own solar system. Even the size distribution of our system is unusual. Elsewhere, the most common are planets smaller than Neptune but larger than Earth; in our system they are completely absent.
The stars hosting the planets vary. Some are the same size as the Sun, some bigger, some smaller. Stars, brown dwarfs and giant gas planets form a continuum (Chen & Kipping 2017). Brown dwarfs are simply gas giants between 13 and 80 Jupiter masses, that is, big enough to fuse deuterium (hydrogen that already contains a neutron) into helium but not big enough to fuse simple hydrogen.
Most stars occur as binaries, with one usually larger than the other. In such cases, a planet may orbit either both stars or only one. More commonly, planets orbit single non-binary stars, as if the planet were the equivalent of a second star. Some planets are free-floating: they do not have hosts at all, but like stars occur either singly or in pairs. They contradict current theories of both star and planet formation (Langeveld et al. 2024) and suggest that stars and gaseous planets form as whole bodies in a common process.
Generally a planet’s composition is inferred from its density, mass divided by volume. A planet is rocky if its density is high and gaseous if it is low. Densities vary, and there is considerable latitude in modelling the compositional mix. With gaseous planets, the more massive they are, the denser, because of the gas’s compressing under its own gravity. WASP-76b, one of the few planets to have been analysed spectrally, is ultra-hot and of roughly the same composition as its star, consistent with having the same origin (Pelletier et al. 2023).
Rocky exoplanets are a distinct group of low mass and radius. Owing to the star’s gravitational pull, one would expect mass to decrease with orbital distance, but in fact it tends to increase, and most of the bodies are more massive than Earth. In contrast to the solar system the vast majority lie at distances between 0.01 and 0.7 AU and the space beyond 10 AU is a complete blank.
Gaseous planets mostly fall into two groups, those orbiting closer to the star than 0.2 AU and those orbiting further than 0.5 AU. Beyond 0.1 AU, size is fairly constant, at around 11–13 Earth radii, because cooler temperatures increase the density and so counterbalance increasing mass. In the solar system, the mass of the non-rocky planets decreases with distance. Saturn, Uranus and Neptune all lie beyond the exoplanet field and must have formed in circumstances differing from those of their counterparts. Rocky and gaseous planets are discontinuous, contrary to what one might expect if both types formed from a disc and the gas fraction uniformly increased with distance.
Many of the gas giants lie closer to their star even than Mercury. Those with orbits shorter than 10 Earth days are highly inflated and dubbed ‘hot Jupiters’. Ostensibly, their closeness to the star negates the nebula hypothesis, firstly because the intense heat would have prevented condensation and secondly because the violent winds typical of young stars would have blown the raw material away. The standard get-out is that they migrated to their positions from colder regions. However, despite orbiting where rocky planets might be expected, most hot Jupiters are entirely solitary, and in the few cases where they are not, their nearest neighbours are also gaseous so far as we can tell (Wu et al. 2023). That all hot Jupiters migrated to their observed positions is implausible and mooted only because of the need to make other solar systems conform to the narrative devised for our own. Indeed, our gas and ice giants are so difficult to explain in their present positions they are thought to have migrated in the opposite direction, from close-in outwards.
Whereas cold gaseous giants are comparatively rare, hot Jupiters are common. They orbit close to their star and appear to have issued directly from the star, not from any ‘protoplanetary’ disc. One planet, WASP-18b, has ten times the mass of Jupiter, orbits its star in less than a day at a distance 50 times closer than the Earth from the Sun, and is thought to have been spiralling inward over less than 5 million years. This is much less than the age of the star itself, thought to be 0.5–1.5 billion years old (Hellier et al. 2009). KELT-9b has an orbital period of 36 hours and a daytime temperature of 4,300° C, hotter than the surface of some stars. Some of these hot giants are disproportionately large compared to the star (Kanodia et al. 2023, Bryant et al. 2023, Steffánson et al. 2023). According to the standard accretion model they should not exist, since less massive stars condense from less massive discs and therefore their planets should be less massive. The obvious explanation is that they originated more or less fully formed.
Life requires that a planet’s temperature be within a narrow range and its orbit therefore close to circular. The orbits of most exoplanets, especially at distances greater than 1 AU, are highly elliptical, in the range 0.1–0.9 (where 0 is circular and 1 parabolic), again in contrast to our own system. Also, some orbit at a high angle to the equatorial plane of the star. In a study investigating 57 cases where the star’s equatorial plane could be determined (Albrecht et al. 2021) only a minority orbited at less than 7° to the plane; some inclinations were as high as 80–124°, tipping into orbits opposite to the star’s spin. One such contrarian, the hot Jupiter TIC 241249530 b, has an eccentricity of 0.94. These are not the attributes of a planet that condensed from a protostellar disc.
Naturalistic theory predicts that more than a third of the systems with giant planets will turn out to host Earth-like planets, including water-rich planets on stable orbits (Raymond et al. 2006). Instruments are now capable of detecting even dwarf exoplanets, but the prediction continues to fall flat. The majority of rocky exoplanets are more massive than the Earth and have much faster orbits. The rocky planet Kepler 10b caused excitement because it had a radius just 1.4 times that of Earth’s. One academic hailed it as “among the most profound scientific discoveries in human history”. However, it was twenty times closer to its star than Mercury and its surface temperature exceeded 1300° C. In 2013 astronomers found a planet, Kepler 78b, with the same mass as Earth – but again, too warm, with a surface temperature exceeding 2000° C and orbiting its star in just 8.5 hours. In 2015 GJ 1132b was hailed as possibly ‘the most important world ever found beyond the solar system’; again it was necessary to read the small print, for its orbit was also too close to its star, a red dwarf, to keep liquid water.
The orbital range within which water can exist is called the ‘habitable zone’. In January 2023 NASA announced the discovery of an Earth-sized planet, TOI 700e, possibly cool enough for water, assuming it has an atmosphere to retain it. Nonetheless, whether it does harbour water is unknown. To date, no rocky planet has been found with water on the surface. It suits scientists to hype up their discoveries in press releases and have us believe that life is an accident just waiting to happen. Creation theory maintains that life, even in the broad sense that includes bacteria and plants, requires creation, and since the Earth was the only place in the universe where life is said to have been created, it predicts that life will not be found anywhere else – not even in our own solar system.
In sum, it remains true that ‘the origin of the Solar System represents one of the oldest unsolved problems in science’ (Taylor 2004). Among the many thousands detected no system resembles our own, and the most Earth-like body is not any exoplanet but Mars, just next door. Our immediate neighbourhood resists a naturalistic solution and therefore points to a theistic one, even though we do not see it in its originally created state. The case is not of course closed. In the face of a perceived problem or an unpalatable solution, one may always hope that the key insight awaits discovery. In science, conclusions always remain provisional. Nonetheless, the only data we ever have are the data available now. We have one short life in which to make up our minds and the balance of probabilities does not suggest that the solar system came about by chance.
The pages following provide an alternative explanation of asteroids, moons and the Kuiper Belt, beginning with
2. Chondritic meteorites.
