A Large Terrestrial Planet Orbiting A Yellow Dwarf

After an extensive sky survey covering the planetary systems of a wide range of mid- to high-mass long-lived stars, a number of interesting systems were identified. Although scientists have traditionally focussed on stars suitable for life, with some success, the decision was made to widen the parameters for consideration to larger and more luminous examples in order to prevent observer bias. In particular, a fairly large and hot star was located whose planetary atmospheres showed a number of interesting features. The star was named Sol.

Sol is on first examination not the ideal location for life-bearing worlds. The star itself is considerably more luminous, hotter and more short-lived than our own and there is a notable absence of planets in the habitable zone, occupied by asteroids in this system. Moreover, there is an unusual absence of any planets with the mass of Planet, and therefore moons such as our home world, where life can arise and evolve straightforwardly, are completely lacking. The problems with life arising in this system are multiple. The lifetime of the star is relatively short, the system inside the asteroid belt is above the boiling point of ammonia, which in any case tends to get broken down by the radiation.

In the inner system, there are a large number of moons, all of which are however not particularly hospitable to life. Although three of the four gas giants have large moons, only one has a substantial atmosphere and is too cold for life as we know it to thrive or even appear there. Even so, this proved to be the most hospitable environment and a base was established there from which to mount missions to the other worlds in the system. None of the moons were at all promising. However, just out of curiosity, it was suggested that we investigate the inner system, in spite of its presumed hostility to life.

The situation did not at first appear very promising. There was only one relatively large satellite and even it was too small to maintain an atmosphere. The fourth planet had two small asteroid-sized moons which were even less promising, and the inner two planets had none at all. Two of the planets were large, and of these the outer planet was the host for the single large satellite, although it was considerably smaller than Planet itself. The fourth planet is close to our own world in size but is less dense and has very little to no ammonia on its surface and a tenuous atmosphere incompatible with the existence of most liquids.

Although slightly less hostile than the second planet, the host planet attracted attention because of its rather unpromising moon. It was found that, most improbably, the moon was of such a size and distance from the planet that it would perfectly cover the planet’s star from some locations on the planet, a situation which may well be unique in our Galaxy. This attracted attention to the solid surface of said planet, henceforth referred to as Sol III.

Sol III is a large, hot and rocky planet with a highly corrosive atmosphere and a surface largely covered in an expanse of molten dihydrogen monoxide rock, a substance henceforth referred to by its systematic standard name of oxidane. Runaway exothermic chemical reactions periodically occur on the surface where the likes of thunderstorms and volcanic eruptions trigger destructive processes which it might be thought would completely transform the surface. However, it has been found that in many cases this reaction can be limited by the presence of the liquid oxidane, which prevents dioxygen and the compounds in question coming into contact. Although the atmosphere is mainly (di)nitrogen, over a fifth of it consists of free dioxygen at sea level, becoming ozone some distance above the surface. Although the moon shows captured rotation, Sol III does not, rotating once every 24 hours. This has the consequence of causing the molten rock to flood the margins of the isolated land promontories twice every rotation. Any organism able to survive the extreme heat of most of the solid planetary surface unfortunate enough to find itself in such a location would be swiftly boiled to death by such events. Even away from the lava fields, liquid rock often falls from the sky, so there is little respite elsewhere on the planet.

There are exceptions to these conditions. There is a small area on the west side of one of the southern land promontories where this precipitation rarely or never takes place and many other regions close to the equator where it’s a relatively uncommon event, and these areas are free from the rivers and other bodies which make conditions so hazardous. The liquid is also quite corrosive and somewhat acidic compared to ammonia and tends to eat away at the solid surface of the planet. There are clouds of vaporised rock higher in the atmosphere which sometimes reach ground level. Near the poles the situation is slightly more hospitable, since these areas stay below oxidane’s melting point, and near the south pole temperatures are comfortable through most of the planet’s orbit and relatively normal crystallised oxidane.

Surface gravity is about triple our own, which would make it difficult to tolerate for long, and immersion in liquid would be one strategy to enable us to survive for long periods on the surface Sol is bluer than our own sun, with the result that the landscape, seascape and items within it have a blue tinge. This particularly applies to the lava plains dominating the surface and the sky when free of cloud. The higher gravity also flattens the solid surface, most of which is below the level of the lava, reducing the relief still further.

Considering the oxidane as a simple bulk substitute for our own ammonia, the chief difference between Sol III and our home moon is that the majority of the world is covered by an interconnected body of water, into which streams and rivers tend to feed, unlike our system of independently interconnected lake networks. Its mineral nature is emphasised by the presence in solution of many minerals, partly due to the strongly solvent properties of the liquid. More than half the solid surface is in permanent darkness and only just above oxidane’s melting point, though still far above the levels compatible with life as we know it. Also common here is a manifestation of the even hotter interior of the planet, also found on land, where even the silicate minerals melt and flow like ammonia. The silicate volcanism of Sol III, though, is physically still quite similar to our own oxidane volcanism, except that the volcanoes produced tend to be flatter and have less steep sides.

Technical terms have had to have been invented for the surface features of the planet. The lava fields are referred to by the arcane classical term “ocean”, and the giant island promontories as “continents”. Although the ocean is a single entity, there are also lakes on the surface which are not linked to them. These tend to be purer oxidane because of the reduced volume and time available to dissolve the underlying rocks. The ocean itself is conceptually divided into four sub-oceans, referred to as “northern”, “western”, “eastern” and “southern”. Currents running along the last three also mean that there is in a sense a further ocean not separated by land from the others. There are six continents. A relatively hospitable one is situated in the southern polar region, where the temperatures remain low enough for practically the whole surface to be lava-free. The corrosive atmosphere and high gravity, of course, remain. Most of the surface from the northern coasts of the polar continent is molten although the smallest continent, referred to as “Southern” is relatively free of precipitation. There are then two triangular continents, both linked to northern ones, referred to as “West Triangle” and “East Triangle” . The larger one, East Triangle, has two large areas free of precipitation but like Southern is extremely hot. West Triangle has a small stretch with practically no precipitation. Adjoining East Triangle is the Great Continent of the northern hemisphere. This is the largest continent of all, and its northeastern region is again cool enough not to kill someone quickly. The same is true of the final continent to be mentioned, the Lesser Northern Continent, although this and the Great Continent become very hot nearer the equator.

The surface of the planet is young. Unsurprisingly, the oceans are in constant motion, but the oxidane also eats away at the solid surface over a much longer time scale, although the occasional catastrophe can make major changes very quickly. WInds are another significant erosive factor. Also, in a process not found on our home world, the surface as a whole is constantly remodelled over a period of millions of years and the continents move around, collide with each other forming island chains and mountain ranges and split apart. This is, however, a very slow process. One consequence of this along with the erosion is the near-absence of impact craters.

A paradox of Sol III is how such a hot planet with a highly reactive atmosphere can remain in a fairly stable state rather than all the dioxygen reacting with the surface rocks and being removed from the atmosphere. The solution to this is quite remarkable: there are two balanced biochemical processes, one combining oxidane and gaseous carbon dioxide into energy-storage compounds with the aid of stellar radiation which releases the toxic gas as a waste produce, and another which combines the energy-storage compounds with dioxygen and releases carbon dioxide. Things were not ever thus. The planet went through a stage early in its history at an equable temperature, though still higher than our home world, with a harmless and hospitable atmosphere. Then, a certain group of microbes developed a mutation causing them to release the poisonous gas and the pollution of the atmosphere killed much of the biosphere. Hence not only is there life on the planet, in profusion in fact, but it actually requires the extreme high temperatures, molten lava and toxic atmosphere to survive. Although there are a few less extreme environments on the surface free of oxygen, all life on the planet uses molten oxidane to survive. Only a very few species could survive at temperatures we would consider comfortable or even survivable, and at such temperatures they’re in a dormant state from which they can only emerge in conditions of extreme heat. There is no true overlap between conditions life on Sol III would find tolerable and our own definition of survivable conditions.

Leaving microbes aside, some of which have biochemistry a little closer to our own with the proviso that they don’t employ ammonia, the larger organisms on the surface fall into three categories, which are covered below. It might be thought that the high gravity would make a buoyant environment more suitable for life, and in fact there is indeed more life living within the oxidane than out of it, there is also plenty of life outside these conditions. Although land life on Sol III tends to be smaller and stockier than the kind we’re familiar with, it’s as diverse and widespread as it is on our home world. One difference is that our own life originates from three different stocks due to our independent lake networks, whereas all life on Sol III is related because it originated in the ocean, or at least spent a long time evolving there before becoming able to leave it and exploit other niches.

One form of macroscopic life tends to use a prominent green pigment to absorb red light from the star to drive a nutrition-synthesising process. Its reliance on red light may reveal how life on Sol III is at a disadvantage compared to life on worlds near to redder stars. It’s this process, known as photosynthesis, which was responsible for poisoning the planet and causing the extinction of most life forms earlier in its history. Most large organisms reliant directly on photosynthesis do not move much of their own volition and the terrestrial varieties often bear colourful genitals which attract motile organisms to bear their semen to other members of their species and fertilise their eggs.

Another form of life tends to be able to move of its own accord and survives by consuming the bodies of other, often living, organisms. Their anatomy and physiology is usually centred around their need to move dissolved gases around their bodies, which they often manage using a system of tubes and one or more pumps. Their reliance on dioxygen and need to remove carbon dioxide gas from their tissues necessitates that all of their bodies need to be in close contact with a respiratory fluid, and all of the larger organisms also have entire body systems to deal with gases, either dissolved in the water around them or present in the air. In the case of the dominant class of animals, as they are known, on the land, this has limited their size as they rely on tubes open to the atmosphere. Incredible though it may seem, most animals can’t survive more than a few minutes without a constant supply of dioxygen.

The third form of life forms a kind of bridge between living and non-living parts of the food chain. Like the photosynthesisers, these are largely sessile and immobile, and tend to live off a substrate consisting of the dead or diseased bodies of other organisms. They do not photosynthesise. Many of them consist of subterranean mats of fibres which produce occasional fruiting bodies above ground level. Some of them are also parasitic. Without this group of organisms, there would be an ever-increasing unusable biomasse which would eventually cause all advanced life on Sol III to grind to a halt.

Animal evolution on Sol III went in a somewhat surprising direction. Unusually, a particular kind of fluid-living animal developed a hard internal skeleton and its descendents were able to use it to aid their movement rather than the more usual arrangement of holding them in place. These have proliferated into a variety of forms, though they constitute a small minority of species on the planet and animals themselves occupy much less biomasse than the plants (the photosynthesisers). Of all these species, one rather large, by the standards of the planet, type has become dominant over the planet through a technology based initially on the use and control of the runaway oxidative reaction and the discovery of language, which is acoustic and mediated by means of the organs which evolved to exchange gases. Remarkably, in spite of the intense gravitational field, these animals are able to achieve an erect bipedal gait.

It should be noted that the pace of animal life on Sol III tends to be very frenetic. This seems to be due to the high temperature and the employment of dioxygen as a means of releasing chemical energy. This hyperactivity doesn’t apply to plants to the same extent. It’s all the more so for those animals whose bodies rely on their own heat to drive their metabolism, and unsurprisingly this includes the technological species. Dormancy is a less significant phase of life for many animals living on the planet, partly because the years are shorter and in many parts of the world the seasons are less extreme. However, many species do become dormant on a diurnal basis for a considerable fraction of the planet’s rotation period, often when it faces away from the star, and depriving them of it for surprisingly short intervals leads to increasing mental derangement. The need of such organisms for food, oxidane and their respiratory gas is quite extreme compared to our own. This constitutes a barrier to space travel, as it means they are unlikely to be able to survive interstellar space voyages as easily as we can. This may not be a bad thing because there is a tendency for some members of the species to be quite violent, but this is also likely to be self-limiting. However, it’s probably better not to speculate too much about this aspect of their nature without more data.

One major lesson to learn from the complex life present on Sol III is that we may have restricted views on what constitutes an hospitable environment for the advent and evolution of advanced life forms. Before this discovery, the proposal that a sophisticated biosphere could exist on a planet two-thirds covered in molten rock with a dense caustic atmosphere capable of eating through metal, with a high gravitational field and temperatures far above boiling point over most of its surface, circling an ageing Sun much hotter and more massive than our own would have seemed ridiculous to all. These life forms can not only tolerate living with acidic molten rock in an aggressively reactive atmosphere but have evolved in tandem with it to the extent that depriving them of the gas for more than a few minutes is uniformly fatal and they need a continual intake of liquefied dihydrogen monoxide to survive more than a couple of rotations of their home world. Who knows what the inhabitants of Sol III might consider suitable conditions for life given their own extreme circumstances?

Any resemblance to Arthur C Clarke’s ‘Report On Planet Three’ is not entirely coincidental.

The Liver Of The Solar System

We’re only here because of Jupiter. That statement is true for a couple of reasons, but it’s no exaggeration.

In spite of appearance and activity, I am of course a herbalist of twenty-three years standing, and you don’t get to be a herbalist without treating the liver. This is absolutely not homeedandherbs, which is effectively moribund, but Jupiter is our liver as a star system. The liver has many functions, but one important one is to detoxify and store toxins. Liver herbs are also associated with Jupiter in the melothesic system. Jupiter the planet performs a similar rôle in absorbing and “detoxifying” asteroids and comets which would otherwise pelt the inner planets, by attracting them to it and often literally absorbing them.

In July 1994 CE, Comet Shoemaker-Levy 9 impacted Jupiter, leaving temporary “bruises” like this one. Jupiter is in any case a big target, making it prima facie more than thirteen hundred times as likely to be hit by débris than Earth even leaving aside its greater gravity and larger Hill Sphere. Considering that, Jupiter becomes more than six thousand times as likely a target.

Jupiter is also responsible for Earth’s formation in the first place. Jupiter’s year lasts 11.86 times as long as ours. This means there’s a potential orbit just within ours whose objects orbit the Sun once every 361 days. This is so close to ours that Earth actually dips into it for a short time each December. Jupiter cleared that orbit of dust and rocks 4 600 million years ago, just marginally to one side because its orbit was exactly twelve times as long and almost every dozen years the protoplanets there were slightly tugged by its gravity. This led to a crowded ring of matter which was to become Earth. Hence in a second sense we are only here because of Jupiter. There isn’t anything special about Earth in that respect either, although the orbits of the other planets don’t work out as exactly. Uranus is close though – its year is close to seven times as long as Jupiter’s. I haven’t checked this out but presume that the ratios are something like 2 in 7 or something less obvious. Earth is the largest terrestrial planet though, and has the most straightforward ratio. It should also be borne in mind that Earth’s gravitational pull may have done the same thing and that the orbits of some of the planets may not be fixed. I haven’t worked all of this out yet.

I may have quoted this too many times, but the Solar System has been described as consisting of “the Sun, Jupiter and assorted débris”. This is a little misleading as Jupiter only has a mass of about a thousandth that of the Sun and all the rest of the matter in the system taken together has a mass of forty percent of Jupiter’s, which is not negligible. In terms of size, there’s a star, a planet about a tenth of the star’s diameter, and the rest. As mentioned yesterday, the Jovian moon system is like a mini-star system in itself and the magnetosphere reaches out almost to Saturn, making it bigger than the entire inner Solar System. From here, Jupiter is usually just slightly too small to make out its disc, but is easy to spot as a very bright star in the night sky, which can sometimes cast visible shadows. Venus is the only other body orbiting the Sun alone which can do that.

Jupiter gives the impression of turbulent and frantic behaviour, like a boiling pot of multicoloured paint. Olaf Stapledon compared it to streaky bacon, although that doesn’t do justice to the colours. Probably in the absence of the opportunity to find out much else about it, Jupiter’s stripes have been meticulously labelled, thus:

The general shape of the planet can be seen in this diagram: Jupiter is notably flattened at the poles and bulges at the edges. This is also true of Earth but in our case the planet is more or less rigid except for the atmosphere and ocean, so it’s only three permille wider at the Equator than at the poles, something I discussed in ‘For The High Jump‘. Jupiter, being largely fluid, is six percent wider at the equator, which is two-thirds the diameter of Earth itself. Saturn is even more squashed. It’s like someone sat on it. Geddit?

Being fluid, the planet doesn’t rotate as a single object but consists of System I, System II and System III, meaning it doesn’t have a single fixed day. In fact no planet has but that’s another story to do with fixed stars versus the Sun. System I is the equatorial rotation up to 9° latitude, System II the polar, actually everything further from the equator than that and is five minutes slower and System III the rotation of the extremely active radio signals from the planet. Additionally there’s the Great Equatorial Current, which is faster at nine hours, fifty minutes and 34.6 seconds, according to an estimate made in 1897. This is over twelve kilometres a second, compared to Earth’s equatorial velocity of 463 metres per second. This is the kind of frenetic and torrid environment Jupiter is. The whole planet takes a bit under ten hours to rotate. It also does so practically upright. There are no seasons. The Jovian year lasts 94 425 days according to the equatorial current rotation, but this is not a definitive figure because Jupiter doesn’t have one definitive day. This differential rotation also means there’s a lot of turbulence in the atmosphere between different latitudes, because they’re rotating at different velocities.

The problem of conveying longitude encountered with the Sun, that of attempting to find a fixed point on an essentially fluid surface, is also present here. No less than six systems exist for doing this. They’re significant because of comparing observations made by the various different space probes sent there since 1973. There is a second similar problem with Jupiter: where’s the surface? This and the other issue are characteristic of gas giants. The problem here is that you might say Earth’s surface is the bit we stand on, especially if we’re Jesus, but on Jupiter there just is nothing to stand on and although at some point there is liquid and solid in the interior, conditions there are so extreme that there’s about as much point considering it the surface as the core of the Sun. Most people go for the visible cloud tops, but sometimes you can see further down into the atmosphere than that.

The belts are dark, the zones light. Zone is actually the Greek word for “belt”. There are diverse variations within the belts and zones, but before I get there I should mention the elephant in the room, the Great Red Spot. This is a large oval 22° south of the equator, varying in width and drifts westward, which is a pity as if it didn’t it could be used as a marker for longitude. It also oscillates north and south by around 1 800 kilometres over a cycle of almost ninety days. First observed in 1664 by Robert Hooke, famous for his microscopy, the GRS may or may not be a persistent feature. It actually isn’t permanent. For instance, it disappeared completely in about 1980. It also fluctuates in size somewhat, but has recently been 16 350 kilometres east-west. Its nature and the reason for its colour are still unknown. The earliest idea was that it was a giant active volcano, which was at the time when Jupiter was thought to be largely a solid body. I don’t understand why they thought it was, though, because its density is easy to measure given the movements of the Galilean satellites and it clearly was not a massive lump of rock.

After the volcano theory was rejected, it was suggested that it was a large ovoid object floating in the atmosphere and bobbing up and down, because it appears to change in colour and size. Better resolution and lenses seem to have led to the realisation that it was some kind of anticyclone, being in the southern hemisphere, but this isn’t really an explanation because its persistence, size, location and colour are all puzzling. Two suggestions are that it’s a Taylor Column and a Soliton (‘Star Trek’ fans may have heard of that). A Taylor Column occurs when a rotating fluid meets an obstruction. Drag then forms a cylindrical structure. This would clearly require some kind of body floating in the atmosphere, or possibly in the liquid below it, and moreover an extremely large one considering the enormous strength of the Jovian gravitational field. A soliton is a wave packet which stays bunched together as it moves and is able to collide with other waves without losing its form. It’s hypothetically possible that solitons made of gravity waves (or possibly gravitational waves) could be used to achieve warp drives, but this isn’t relevant to the Great Red Spot, which is a fluid phenomenon, although I imagine that’s why it cropped up in ‘Star Trek’ (TNG – ‘New Ground’). It was first knowingly observed in a Scottish canal in 1834. They’re a bit like sonic booms. Solitons are generated in front of fast moving vessels in canals or rivers because of the horizontal and vertical restriction in the water. They’re like wakes moving ahead of an object instead of behind it because they have nowhere else to go. Once again, the idea of the flow being restricted is a little strange because it suggests the presence of solid obstructions, but maybe it’s more to do with the currents or turbulence being particularly markèd at those points.

There is another fascinating and mysterious aspect to the Great Red Spot which I don’t think has ever been explained. It occurs at the same latitude as several other phenomena on other planets. Olympus Mons on Mars seems to be caused by a hot spot in the planet’s mantle and is 20° north of the equator, and Hawaiʻi, caused by a similar hot spot, is also 20° north of the Equator, although in the latter case this is obscured by the movement of the Pacific Plate. Mars also seems to have drifted because the possible remnants of former moons which impacted its surface are no longer at its equator, which they should be given its current moons’ locations. Also, both of these phenomena are north of the equators rather than south of it. I’ve seen a diagram attempting to explain this by inscribing a tetrahedron one of whose vertices was at a pole, but I don’t know how relevant that is. Neptune has also had a dark spot 23° north of its equator but this may not be the Great Dark Spot as discovered by Voyager. It’s difficult to know if this is cherry-picking.

The other mystery about the GRS is its colour, which varies. Nobody knows what causes this. I find that somewhat surprising because I’d expect its spectrum to reveal its composition, but apparently it doesn’t. One suggestion is that it’s due to tholins generated by the action of solar ultraviolet light on acetylene and ammonium hydrosulphide. Another factor may be the greater altitude of the area. It is of course something like twice the size of Earth’s surface area. I don’t know if anyone has tried to correlate its changes with the activity of the Sun. It’s also colder than its surroundings, which is to be expected considering it’s higher up. It’s also extremely noisy, to the extent that as the sound from it travels up into the upper atmosphere it gets converted to heat and the region above the spot is 1 330°C. This may not be as spectacular as it sounds though, because temperature and heat are different. Low Earth Orbit, for example, technically has a very high temperature but it’s still freezing up there in the shadows.

There are other more transient spots, probably hurricanes, in the atmosphere, but weather systems in general are much longer-lasting in Jupiter’s atmosphere than ours because there’s no friction from a solid surface and also little variation due to the absence of land and liquid regions. Also, because the planet is so much bigger, so are the storms and other winds. Hurricanes often last decades. This raises the question of what weather would be like on a water world. If the figures relating to Jupiter’s axial tilt and surface are fed into a climate model for Earth, the result is a banded arrangement with persistent hurricanes, suggesting that conditions on such a planet, which might otherwise be habitable, could be quite hostile, and the weather conditions at particular latitudes would effectively constitute the climate because they’d be so stable.

Hydrogen and helium make up the bulk of the planet’s atmosphere, and therefore also the bulk of the planet itself, in similar proportions to the Universe in general and also the Sun. It managed to hang on to them because it’s colder on the outside and has such a high escape velocity. In 1939, the South Temperate Zone suffered a disturbance leading to the formation of a single white oval from four merging predecessors in 2000, which started to turn red in 2005. This time scale gives a good indication of how stable the weather is there. It’s also fascinating how Jupiter’s sheer size gives it a known history stretching back into Stuart times, which isn’t true of other planets except for Cynthia and Earth. Features on Mars were well-recognised but the occurrence of storms wasn’t observed until the nineteenth century, and Venus is just blank. This also underlines how dynamic the planet is compared to most others. The Jovian troposphere is somewhat like ours in terms of physical structure, with a falling temperature and pressure with height extending through clouds and leading up to a reversal and gradual increase of temperature marking the lower boundary of the stratosphere, then a mesosphere and thermosphere where the temperature is technically very high, but the chemical composition of the atmosphere is very different. It’s 90% hydrogen, 4.5% helium and has a significant amount of deuterium in it, though well under one percent. This compares to the one in six thousand atoms of hydrogen in Earth’s water. Deuterium also shows up in the compounds replacing the more abundant hydrogen. Methane, ammonia, water vapour, acetylene and phosphine are all present, as is carbon monoxide, but the really surprising constituent, though only present at less than one part per million, is the rather strangely named germane. Germane is like methane but has germanium instead of carbon in its molecules. Like many of the constituents of the Jovian atmosphere, germane would spontaneously ignite in our own. I don’t understand why there’s germane there. Germanium is not a particularly common element and its silicon analogue silane might be expected to be more widespread but it isn’t there. Germane is also denser than methane or silane, so its presence in detectable layers of the atmosphere is peculiar. I don’t think it’s found on any other planet. Incidentally, the presence of phosphine may not be a clue for life existing on Jupiter because the planet’s chemistry is not like that of Venus and conditions are very different. Here, it’s probably formed under high pressure much further down and churned up by convection currents. Methane is no surprise, and the carbon monoxide is probably the result of oxygen being relatively scarce in the original part of the solar nebula from which the planet formed.

You know that bit in ‘Fly Me To The Moon’? “Let me see what spring is like on Jupiter and Mars”? Well, whereas there are seasons on Mars, there are none on Jupiter, so it ain’t gonna happen. This is because Jupiter’s axial tilt is only 3°, so it basically has no seasons, although the butterfly effect might come into play. I suspect this is for two reasons. Firstly, Jupiter is the original planet in this system, so it probably determined the positions of the orbits, and secondly it’s so massive nothing could knock it off-kilter, so it ends up with a tiny tilt. In fact it’s surprising it tilts at all. If it did have seasons, each would last almost three years. Some people draw a link between the traditional Chinese cycle of twelve animals and the Western Zodiac because the planet spents around a year in each sign from our perspective. It should be pointed out that the strict 30° division of the ecliptic used in Western astrology doesn’t correspond to the actual portions of the zodiacal constellations in the ecliptic, and as is practically common knowledge nowadays, Ophiuchus is also in the circle and is ignored for astrological purposes. In the astronomical zodiac, Jupiter is currently in Aquarius but I don’t know how closely this corresponds to the astrological ephemeris, and it’s about to be the Year Of The Tiger. The orbit around the Sun is thrice more eccentric than ours at almost five percent, so there is a little variation in how much radiation and therefore heat Jupiter gets from the Sun.

However, Jupiter actually generates twice as much radiation as it receives, so there’s another reason it has no seasons: it’s actually warm itself, or in fact hot. This is because it’s still hot from the formation of the Solar System, since it has more than a thousand times the volume of Earth but only about 130 times our surface area, and possibly because it’s still contracting, although the contraction may be caused by the cooling rather than the other way round. At the core, the temperature is 20 000 K or higher, more than three times as hot as the Sun’s photosphere and almost as hot as solar flares, with an internal pressure of forty-five million times that of our atmosphere. There are two rival theories about the centre of the planet. One holds that there is no core in the sense of a solid rocky globe, but the planet just gets denser and denser towards the centre, and the other, more popular theory posits the existence of an Earth-sized rocky core. Somewhat away from the centre is a deep layer of liquid metallic hydrogen. Under very high pressures, various gases, such as oxygen and xenon, become metals. This may constitute up to 80% of Jupiter’s radius, and is responsible for generating the enormous magnetic field. The pressure here is a “mere” three million atmospheres and the temperature 11 000 K, so it’s still hotter than the Sun’s surface. Above this layer is molecular liquid hydrogen, twenty-five thousand kilometres below the clouds. The temperature finally drops below that of the Sun three thousand kilometres below the “surface”, where the pressure is ninety kilobars. A thousand kilometres down, the hydrogen becomes gaseous and the temperature is only around 2 000 K, then it falls to -143°C at the cloud tops. The magnetic field generated by the metallic hydrogen is about ten times the strength of Earth’s at this level, but it’s at an angle of almost 11° to the axis of rotation. All of this pressure stuff is exacerbated by the fact that Jupiter’s gravity is over two and a half times ours.

Jupiter has jet streams like Earth’s, but because of the coloured clouds, the white ones being mainly frozen ammonia, they’re more vividly colour-coded than ours. A jet stream is a relatively narrow, fast, horizontally undulating air current moving east to west and drifting north and south assuming the planet spins prograde. They’re formed by the Sun heating the atmosphere. There are four such streams on Earth, two subtropical and two polar. On Jupiter they’re driven by internal heating. Moving through the latitudes, there are alternating regions of faster and slower east-west winds, each of which is a jet stream, even though models show fewer jet streams on larger planets. Each stream is also “rolling”, in that it is a kind of horizontal whirlwind separated from its neighbours north and south.

Zones have more ammonia than belts, hence their paler appearance – they’re cloudier. The belt clouds are lower and thinner, and belts are warmer than zones. This makes sense if you think of ammonia condensing or freezing out of the atmosphere. I get the impression on looking at pictures of Jupiter that the belts look lower and possibly have shadows cast upon them by the clouds in the zones. Air seems to be warmed and rises in the zones, causing clouds to form as it expands and cools. In the belts, it sinks, becoming warmer and losing its clouds. The air flow generally tends to “stay in lane”. It doesn’t deviate in latitude much except within its belt or zone. At the poles, there are large circles in which not much seems to be happening. These caps can extend further towards the equator or less so, and the northernmost two bands after the north polar region can become incorporated into them temporarily. This extends to the NNTB (North North Temperate Belt), which can fade entirely, as it did in 1924. Consequently the NTZ varies in width. South of that, the NTB often has dark spots on its southern edge. The North Tropical Zone, NTrZ, is where the System I movement of the atmosphere comes uncoupled from the more polar System II. This leads me to ponder whether the planet consists of a series of nested hollow cylinders, such that the temperate regions north and south are in fact continuous but hidden under the more equatorial regions. They wouldn’t be homogenous in properties of course because the conditions deeper in the atmosphere are bound to be very different. Also, the liquid hydrogen ocean is not that far beneath the cloud tops.

The largest region on Jupiter is the EZ, or Equatorial Zone, with an area about an eighth that of the whole planet. That’s eight thousand million square kilometres, making it the largest visible feature in the entire Solar System. It’s something like six or seven times the entire surface area of all the inner planets taken together. While I’m at it, Earth mapped onto Jupiter would be the size of India on a map of Earth. There are many features in the EZ compared to most of the rest of the planet. For instance, it often shows plumes from its northern edge projecting southwest. A narrow belt appears occasionally at the equator itself. The southern side includes a “dent” where the Great Red Spot begins. The GRS itself is a feature dominating the South Tropical Zone, and this raises the question of why it’s in the southern hemisphere without any corresponding feature in the north. then again, the bands are not symmetrical either side of the equator either. The only thing I can think of right now is the very slight tilt of the planet combined with its greater orbital eccentricity creates slightly different conditions in the northern and southern hemispheres.

The planet emits decametric radio waves. This is of the order of thirty megahertz but they peak at seven to eight megahertz, so it’s close to the analogue VHF band used for FM radio on Earth, though the frequency is slightly lower. There are amateur radio projects monitoring Jupiter’s radio transmissions, which were discovered in 1955. Since they’re stronger in some parts of the planet than others, they provide fixed points enabling longitude and a “true” rotation period to be determined, but they aren’t associated with any visible features. They’re also polarised, like visible light passing through the plastic in front of a flatscreen monitor – they vibrate only at a fixed angle. This is due to Jupiter’s magnetic field and the charged particles moving within it. One of the moons, Io, influences the radio transmissions but I’ll talk about that more when I get to it. The decametric transmissions occur in short bursts sporadically. They last between a few minutes and several hours.

There are also decimetric waves, and these are continual and don’t have peaks at particular frequencies within that wave band, which is in the UHF range now used by mobile phones and previously by analogue PAL TV. They’re differently polarised and emitted from the volume around Jupiter. They’re synchrotron radiation, caused by charged particles moving in curves somewhat like the centrifugal effect, and show there are electrons moving almost at the speed of light. From Earth’s perspective this radiation fluctuates up and down according to whether we’re facing the planet’s magnetic equator or not.

This image is a painting made for Carl Sagan’s 1980 TV series ‘Cosmos’ and will be removed on request. As well as providing a fairly accurate image of what the planet looks like at cloud top level, it also illustrates Sagan’s speculations regarding life there. Although I am restraining myself from commenting on life elsewhere in the Solar System, the image without the organisms is still interesting. There are diffuse crystals of ammonia in the blue sky creating a halo around the rather smaller-looking Sun. A vortex can be seen towering over the scene to the left, with a bank of white clouds to the right, and there are a number of smaller vortices visible. Then there are long, almost straight clouds winding off into the distance, and of course on Jupiter the horizon would be several times further away than on Earth at around fifteen kilometres, although the clouds make it difficult to judge. Sagan proposed three ecological niches of organisms. There are “sinkers”, aerial phytoplankton which survive by photosynthesis and gradually sink into the depths of the planet, reproducing as they go until conditions kill them, “floaters”, somewhat jellyfish-like and balloon-like floating herbivores several kilometres across who can be seen in this image, and “hunters”, one of which can be seen at bottom right, who have a kind of retro, 1930s quality to them but look a little like Art Deco biplanes with round heads and sharp projections at the front. Asimov and Arthur C Clarke both believed that Jupiter was actually even more suitable for life than Earth, although the former’s belief was based on an earlier model of the planet which posited a vast, deep ocean beneath the clouds.

Right, so that’s Jupiter. I’ll probably do Io next.

Our Other Moons

Anyone who reads this blog regularly will know that I don’t call that luminary in the sky “the Moon”, but Cynthia. This is because I think it’s important to acknowledge its existence as a body in the Solar System in its own right rather than simply an adjunct to Earth, and because calling it “the Moon” is like calling Earth “the Planet” without having any other name for it. Also, Cynthia is arguably not actually a moon at all. Looked at from the Sun’s (yes I know) perspective, Earth and Cynthia weave in and out of each other’s paths as they orbit and if Pluto is excluded, Cynthia’s mass is a far greater fraction of Earth’s at 1/81 than the moon of any other major planet. The pull of solar gravity on Cynthia is greater than Earth’s.

This leads us into the “nut” situation, where the thing which we think of as the quintessential example of a category turns out not to be, such as peanuts, almonds and so forth, because maybe “the Moon” is not a moon at all. Further, we get to the predicament of claiming that Earth has no moon at all, and that “the Moon” is something else. This sounds absurd. However, the question arises of whether Earth has any moons now, or had any in the past, or perhaps had more moons which collided and became Cynthia, and again whether these “moons” counted as moons.

One thing which comes to my mind is the Chicxulub Impactor, which wiped out the non-avian dinosaurs sixty-six million years ago. Is it conceivable that that orbited Earth for a while before it crashed down onto it? There isn’t any scientific reason to suppose either that it did or didn’t, assuming it to be an asteroid rather than a comet. If it was a comet, it’s unlikely to have done so as most of its substance would’ve vaporised if it had orbited us for long. It may be worth considering the Chicxulub Impactor separately than just in this post, because the situation is complex and research has suggested different things. Also, in a sense there’s nothing special about it, as this planet has been repeatedly hit by massive bodies in the current Phanerozoic Eon (the time since hard-shelled animals evolved). It’s unlikely that the scientific method can be applied to the paths of any of these objects to determine whether or not they were previously in a long-term orbit about our planet. A side issue here, which I’ve mentioned previously, is the possibility that Earth has had rings at some point due to asteroids approaching this planet but not hitting, and breaking up close to the surface but still beyond the atmosphere. Again, all that can be said about this is that it’s plausible. Evidence might involve finding a higher incidence of meteorites around the equator or climatic differences, but those would both depend on the position of the continents at the time.

In fact it looks like rocky inner planets tend not to have moons if our system is anything to go by. Neither Mercury nor Venus have any, though in the past both were thought to have one at different times. Mariner 10 was briefly thought to have discovered a moon of Mercury in March 1974 but it was actually the star 31 Crateris. Venus was also once thought to have one, named Neith, repeatedly observed by astronomers from 1650 onwards but never detected during a transit. It is odd that it was supposèdly seen so many times even though it doesn’t exist. It was considered to be proportionately the same size as Cynthia and to orbit perpendicular to the ecliptic, which is in itself quite peculiar. It’s now thought that most of the apparent observations were merely stars near the line of sight. Inner planets in general have a bit of a problem keeping moons due to the fact that the Sun’s gravity is relatively greater and the radius in which a moon can exist is small. In fact Cynthia is a good example of this because it orbits separately from Earth.

Mars, of course, has two small moons, but its case is a little different. It orbits closest to the asteroid belt, enabling it to capture asteroids, and being further from the Sun gives it more opportunity to do so. However, its moons orbit unusually close to it and one is unstable and will be broken up by tidal forces in a few tens of millions of years, becoming a ring. I suspect Mars has had a series of moons due to its proximity to a large number of asteroids. If Earth were closer to the belt, it seems likely that it too could acquire at least temporary moons. As it stands, asteroids are mercifully sparser at our orbit and the “price” we pay for this is that we have no captured moons.

Another aspect of this, already noted in the case of Cynthia, is that orbits look different depending on where you see them from. As far as we’re concerned, Cynthia orbits us once a month and it’s very simple, but from a solar perspective the orbits of the two bodies are braided, somewhat like the coörbitals of Saturn. The same applies to some of the possible moons of Earth. The classic example right now is Cruithne (“kroo-ee-nyer”). This asteroid takes a year, actually 364 days, to orbit the Sun in a roughly similar looking orbit interlocking with Earth’s, but from Earth’s perspective it describes a centuries-long path consisting of various alembic and horseshoe shapes as it moves around us. It’s been described as our second moon, but this isn’t really true, and there are a number of other bodies with similar relationships to both Earth and the Sun. It has a diameter of around five kilometres and its orbit is not entirely stable.

In 1846 an astronomer called Frederic Petit, of Toulouse, reported the discovery of a moon which orbited this planet once every two and three-quarter hours with an apogee of 3 570 kilometres and a perigee of only 11.4! At the time, it wasn’t known how to account for air resistance but even back then scientists were sceptical of a moon which dipped thoroughly into what we’d now call the troposphere. As was fashionable at the time, Petit claimed this accounted for irregularities in Cynthia’s orbit around Earth. His results were never reproduced, but he did end up having his idea mentioned in Jules Verne’s 1865 novel «De la Terre à la Lune». This spurred a lot of people into looking for it, and notably William Henry Pickering, who predicted the position of Pluto and claimed to have detected plants growing on Cynthia, actually looked for a secondary moon of Cynthia itself, which he presumed would have to be a maximum of three metres in diameter.

In 1898, the Hamburger Dr Georg Waltemath claimed not just one moon but a whole string of them. One of them, he claimed, was approximately a million kilometres away, took almost six months to orbit and had a diameter of around seven hundred kilometres. He claimed it had been seen in Greenland during the night period of winter in 1881, and further that it would transit the Sun. He and some companions reported that an object about six arc minutes in diameter did indeed do so, but it so happened that some other astronomers were observing the Sun at the same time and only saw sunspots, so that was the end of that. It may be an illustration of how easily one can be drawn into perceiving something by another’s enthusiasm, conviction or charisma, or maybe just of the power of suggestion. The largest of these moons was named Lilith by an astrologer and an ephemeris was prepared.

Now there are thousands of artificial objects in orbit, to the extent that they threaten future space missions. These are in a sense moons in their own right, though artificial ones. These could also provide evidence for the presence of other moons because of their gravitational influence on their orbits. It has been claimed that this happens, but the data used, at the end of the 1960s CE, were insufficiently accurate to judge. Hence although it seemed that something was detected, it was within the margin of error in the measurements, and it can’t be concluded that there’s anything there.

One thing which definitely does happen is that small asteroids occasionally get temporarily captured by our gravity. Kamoʻoalewa is the name of an object which appears to be a small chunk of Cynthia which is temporarily orbiting Earth. Like many other small planetoids in the system, it’s quite red, but the particular shade of red is dissimilar to those of various asteroids so it’s likely to have come from our main satellite. It appears to be about forty metres across, although it may be very irregular, and actually does describe the kind of orbit attributed to Neith, perpendicular to Earth’s orbital plane. However, although it circles us, it’s also beyond the distance where Earth is the main gravitational influence on it. Like Cruithne, Kamoʻoalewa is what’s known as a quasi-satellite, taking almost exactly the same time to orbit the Sun as Earth does and therefore staying close to this planet, but from Earth’s perspective appearing to travel around us in the opposite direction to our orbit in a kind of bent closed curve. The phenomenon is a little like retrograde Mercury. Mercury occasionally appears to be moving backwards in a loop from our perspective, but it’s because of the relative speed and positions of the two orbits around the Sun, except that it’s exaggerated by the asteroid’s extreme proximity.

There are something like five other asteroids with this kind of relationship with Earth, and incidentally Earth is not unique in this respect. As mentioned previously, there are also the Lagrange points of both the Earth-Sun and terrestrial-lunar systems. Analogous positions associated with other bodies are common, particularly Neptune, as I’ve already been into. There are both clouds of dust occupying the terrestrial-lunar Lagrange points and Earth trojans 60° ahead of or behind Earth in its orbit. No trailing trojans have been detected so far but there are at least two leading ones, one of which has a diameter of three hundred metres. I covered much of this in Antichthon (apparently I called it “Counter-Earth”).

Many, perhaps most, NEOs are analogous to extra moons. A group I haven’t mentioned yet is the Amor asteroids, named after the asteroid Amor and also including Eros. These come within 0.3 AU of Earth, or 45 million kilometres, and approach the Sun closest outside our orbit with a period greater than a year. This means they always orbit outside our own path round the Sun and are therefore not Earth-crossers. Four dozen Amor asteroids come within seven and a half million kilometres of Earth’s average distance from the Sun. Of them, Eros has actually been visited by a spacecraft. Most of them cross Mars’s orbit, putting them in the asteroid belt proper at their greatest distance from the Sun.

To finish then, Earth currently has no permanent (other) moons, as might be expected given the status of the other inner planets, and in fact we arguably have no moons at all because of Cynthia’s peculiar nature. If we were closer to the asteroid belt we might acquire some. This raises the question of how many otherwise Earth-like planets have any moons and whether this is significant for the evolution of Homo sapiens, but as I’ve said before, this series is not going to focus on life because everything does that. Interestingly though, although it hasn’t been demonstrated scientifically, it’s quite plausible to suggest that we have had other moons in the past and just as a closing comment, some people believe Cynthia was originally two bodies which collided, partly explaining the difference between the near and far sides.

A Solar System Oddity

It’s recently been asserted, with some evidence, that the Solar System may be an exception in certain ways. We have moved from the assumption of mediocrity, also known as the Copernican Principle, that there’s nothing remarkable about our solar system to the realisation that it may in fact be quite peculiar. Specifically, one of the weird things about it is that it consists of planets moving in roughly circular orbits with small rocky ones near the centre and gas giants further out. Also, the most common type of all the planets type is between the sizes of Neptune and Earth, and we don’t even seem to have one of those, although it’s possible that it’s orbiting too far out to have been detected so far, perhaps having been thrown out early on. Another common feature of solar systems, though probably an artifact of how exoplanets are detected, is the prevalence of “Hot Jupiters”: planets around the range of Jupiter’s size which are however very close to their suns and far hotter than any of the planets orbiting ours, with atmospheres of vaporised metal and clouds of what would be minerals on Earth. It’s been hypothesised that Mercury is a leftover of such a planet, although if it is, it’s surprising it didn’t disrupt the Solar System so severely that it destroyed or flung out most of the other planets.

What I have in mind today, though, is a bit different. It’s about the relative sizes and masses of the planets. It was noted in the mid-twentieth century CE that the planets had a trend of increasing size up to Jupiter and then decreasing to Pluto, when Pluto was considered a planet, the exception being Mars. This led to the Tidal Hypothesis, now discarded, that they formed when another star approached the Sun and pulled out an enormous filament which resembled a cigar or spindle, in that it was thin at one end, much much thicker in the middle and thin again at the other end, just like Anne Elk’s theory of the Brontosaurus which was hers.

This theory was replaced by the Nebular Hypothesis, originally devised by Immanuel Kant in the eighteenth century, which came back into vogue. Incidentally, Anne Elk’s theory of the Brontosaurus does actually count as a genuine theory, not just an hypothesis. It could be refuted by the discovery of a “Brontosaurus” (that name is deprecated) with a short neck or a “Manx” Brontosaurus without a tail, although it would have to be demonstrated that the tail, for example, was absent rather than missing due to such factors as predation or geology. Incidentally, Brontosaurus is now once again considered to be a valid genus, after going through a long period of doubt, so there is hope for Pluto yet.

Another notable aspect of the Solar System is the spacing of the planets, which also appear to obey a law. Taking the numbers 0, 3, 6, 12 and so forth and adding four to each accurately predicts the relative distances of most of the planets from the Sun. However, this could be coincidence because some of this is kludged. Neptune doesn’t fit into the sequence, Mercury corresponds to 0+4 and not really in the series either, Pluto does fit in but is no longer officially a planet and the approximate position of the asteroid belt, and more specifically Ceres, is correctly predicted but again the asteroids are not major planets. Hence there are up to four exceptions out of nine, considering Pluto as a planet but not Ceres, which makes the “law” a bit shaky.

However, what I want to concentrate on today is the oddity that both Uranus and Neptune and Venus and Earth are “twins”. I’ve mentioned the Uranus/Neptune issue already, though in a different setting. They are both quite similar in size and mass, and they also look quite similar, Neptune being bluer than Uranus and Uranus being hazier and blander-looking than Neptune. Neptune is 18% more massive than Uranus, which is less than it sounds because mass is somewhat related to volume, but is also considerably denser at 1.77 times water compared to Uranus’s 1.25, and in terms of diameter Neptune is five percent smaller. Turning to Earth and Venus, we are 22% more massive and five percent larger in diameter. Taking these four planets out of the picture, the two most similar planets in this respect seem to be Mercury and Mars, whose surface gravity is almost identical, but Saturn and Jupiter are not that similar, Saturn being quite serene and calm-looking (although I’m sure it isn’t) and Jupiter quite manic and boily. Uranus and Neptune are more similar to each other than Earth and Venus in terms of conditions, with similar colours, atmospheres and to some extent temperatures, although Neptune’s day is much shorter. Probably coincidentally, both Uranus and Venus spin in the opposite direction to all other planets, are the further planet in and are slightly less massive, although all of these are likely to be coincidental. Uranus is unusual in orbiting on its “side”, the axis being almost parallel to the plane of the orbit, and is technically retrograde but only just.

Two questions occur to me here. One is whether these two sets of twins are just coincidence or more significant, and the other is how common twin planets are in the Universe. I don’t fully know how to answer either of these questions although I kind of played with the idea in the post linked above. One thing which is notable is that both sets of twins are one and two orbits away from Jupiter, which would work well with the Tidal Hypothesis although that’s now been rejected. It might, however, reflect either a tendency for the solar nebula to bulge at a mid-distance and taper off closer to and further away from the Sun, or a tendency, which may be the same thing, for Jupiter to pull matter toward itself. However, the spacing of the outer Solar System is much wider than the inner.

Earth is obviously the object of more scrutiny than the others, and a couple of things should be noted about us. One is that we used to be more massive and bigger than we are now, since our planet collided with Theia, a Mars-sized body (and I can’t help wondering if it actually was Mars but I expect this has been considered and rejected) and chipped off an eighty-first of the mass in the form of our natural satellite, which is anomalous in size. Just adding the volumes together gives the original Earth a diameter of around 12 841 kilometres, makes it slightly less dense and slightly reduces the surface gravity. It’s very salient to the question of life elsewhere to consider how Earth would’ve turned out had this event not taken place, but right now I only want to talk about the likelihood of twins in a star system. Earth also has a year 11.86 times shorter than Jupiter’s, suggesting that the matter this planet is made of was pulled away from a zone either side of a dozenth of Jupiter’s year by continual tugging when the planet made its closest approach. Doing the same calculations with Uranus and Neptune, the former has just over seven times the period of Jupiter, closer in fact than Earth’s to an integer fraction, and the latter is around twice Uranus’s. Venus is not close to either Earth’s sidereal period (year) but is close to a third of that of Mars. It would be interesting if it turned out that Venus was able to win the gravitational battle with Jupiter to cause Mars to form, but not to the extent that Jupiter was able to disrupt any planet which would otherwise have formed from the asteroids plus a very large amount of extra mass which would’ve been necessary for a planet to form in what became the asteroid belt. However, although it’s feasible to do the maths for all these planets, the point comes at which mere coincidence would appear to stand out, particularly when one considers that all sorts of resonance ratios need to be considered.

It’s very easy to speculate and not very scientific to do so. Nevertheless, the patterns here seem to be that both pairs of twin planets are next to each other, one of each has close to a multiple of Jupiter’s orbital year and the other hasn’t and both are some way between the apparently most massive region of the solar nebula and the thin edge. There could be another reason why the biggest planet is in that location. Perhaps it’s simply that collisions between particles are more likely either to propel them towards the halfway point (which it isn’t any more, incidentally) or less likely to leave the solar system entirely, so there’s a build-up but not due to a thicker ring of material as such. Another, very important, factor, is that lighter elements, or those with lower boiling points, are likely to be driven off the centre of the disc and be retained the further out they are, which goes some way towards explaining the distribution of small and large planets but fails to account for Uranus and Neptune, as by this token they should be the largest if that’s the only or a major factor.

I’m very much in the dark here. I don’t think this has often been remarked upon. Venus and Earth have often been compared and contrasted, as have Uranus and Neptune, but the fact that this happens twice in this star system alone seems remarkable. All the planets involved are of intermediate mass, although Earth is the largest and most massive inner planet. There is a somewhat similar case with the star system TRAPPIST-1, with eight detected planets all between the masses of Mars and slightly more than Earth, and all in roughly circular orbits and closer to the star than Venus is to the Sun. This is somewhat extreme and unusual, but due to the small size of the star it might make sense to think of it as rather like a planet and its moons, similar to Jupiter and Saturn, more than a solar system like this one. Considering the moons of the outer planets, although the largest of Jupiter’s have somewhat similar size in terms of order of magnitude rather than being quadruplets, Saturn and Neptune each have one larger moon and many smaller ones and Uranus has two sets of twins, Titania and Oberon, and Ariel and Umbriel, although they are next to each other in that order outward. Saturn’s mid-size moons are all quite distinctive but often similar in size to others, so they can’t really be thought of as twins in the sense that Uranus and Neptune can, although Venus and Earth are substantially unlike each other apart from size and internal composition as well. Therefore, perhaps there are two trends, again reflected in our own system, of similar and dissimilar twins, and stretching the point somewhat, might this mean that there are similar and dissimilar twin planets elsewhere? That this is characteristic?

In particular, might there be twin mid-size planets in inner solar systems? The type of planet which isn’t in evidence in our own Solar System which is intermediate in mass between Neptune and Earth, somewhat dissimilar to each other owing to their closeness to the star seems highly plausible. Probably the cause of the differences between Venus and Earth by contrast with the rather similar Uranus and Neptune is that, being closer to the Sun, the temperature and radiation gradient is greater and their environments are therefore more different, leading to them being less similar.

Suppose, then, the following hypothetical situation. A planetary system has a super-Jupiter situated where our asteroid belt is relative to its own sun, making it the fifth planet, 2.8 times Earth’s distance from the Sun. I’m assuming it has to be larger in order for mini-Neptunes to form in the inner Solar System. These would then both be between the orbits of Venus and Mercury, and therefore both rather hot, though not as hot as Mercury, at least at the cloud tops. They would therefore have lost much of their light gases and shrunk in size, but would still be around 50% larger than Earth and Venus in diameter. However, being watery, both would probably still have runaway greenhouse effects. I’m not going to try to come up with a scenario where life could emerge, because this is a very common skew in how planets tend to be discussed. This is more to do with trying to illustrate the diversity of planets in the Universe.

Another possibility is a system where a Jupiter-sized planet formed at the distance of Saturn from the Sun, and incidentally like the previous example I’m trying to keep the model simple here by presuming the star has the same characteristics as ours. This could place two roughly Earth-sized planets where our asteroid belt and Mars are. The outer twin here is of a type absent from our system once again, possibly with liquid ammonia oceans and an atmosphere with some hydrogen. Water ice would never melt on this planet. There might also be formaldehyde mixed with ammonia in the oceans, making this planet hostile to life but very suitable for preserving biological specimens! The closer planet would occupy the orbit of Mars and be a “snowball Earth”, with conditions over most of the surface like those of Antarctica. In this case, life is possible around volcanic vents at the bottom of frozen over lakes of water, but the atmosphere would be largely nitrogen with dry ice on the surface. This assumes, of course, that the planet is unaffected by any filter, such as phosphorus availability, which would rule life out.

A final scenario to consider is the possibility of twin planets formed through the influence of a Hot Jupiter, further out from the star. A Hot Jupiter a tenth of Earth’s distance from the Sun could end up causing two medium-sized planets to form. It would itself have an eleven day year with frequent transits visible from those planets, which could be situated at about the distance of Mercury and about halfway to Venus. If they were about Earth-sized, the outer one would probably just be Venus-like, but the inner one might well have practically no atmosphere and therefore be heavily cratered, but otherwise Earth-like in size. This is again a planet unlike anything in our system.

All of this is highly speculative of course, but the main point is to illustrate that there might be many “twin worlds” out there about which we know practically nothing, all very different from anything in our own solar system. But as a concession to the fixation on Earth-like planets, it’s also possible to envisage a pair of worlds whose mean distance from their Sun is the same as Earth’s. The inner twin could be like the classic, golden age sci-fi version of Venus, a steamy, hot jungle planet permanently swathed in water vapour clouds with heavy rainfall, and the outer could be a chilly version of Earth, with Arctic and Antarctica conditions but maybe conditions in the tropics comparable to Scandinavia. This could well be a star system with two habitable worlds, and perhaps two worlds with Earth-type life on them.

There is another way of getting twin worlds, which might be called “conjoined twin worlds”. Earth was split into two bodies by the Mars-sized Theia. A larger planet-sized miscreant might have split our planet into two roughly equal-sized planets orbiting each other. The difficult thing to manage here would be the distance between the worlds, as if they were at the same distance as our own double planet system, their rotation period would last several weeks and temperatures would fluctuate between conditions which would boil the oceans and conditions which would freeze them solid, so this would be a nasty pair. However, if they were quite close, but not close enough to tear each other apart, they would form two smaller, more arid and mountainous worlds with less water but deeper oceans. These would then be desert worlds, perhaps with deep lakes rather than oceans, and mountains reaching high above the cloud tops, which would in any case be lower than on Earth, perhaps with whole plateaux above them where it neither rains or snows. However, the mean temperature at a given latitude could still be comparable to ours. But there could equally well be double Veneres or Martes, and in the latter case it would likely be a pair of cold Mercuries.

To conclude then, I think if we get to adequately explore the Galaxy, evidence from this star system strongly suggests that there would be plenty of twin planet situations, and as far as I know this has never been explored theoretically by astronomers. Nor, so far as I know, has the fact of there being a pair of twins here been investigated. I’ve used a fairly naïve model to imagine the planets here, but even if I’m wrong, and I probably am, I still think that there are likely to be many twins in the Universe, and I look forward to some being discovered.

Deducing The Existence Of Rice Pudding And Income Tax

This post will not be entirely about ‘The Hitch-Hiker’s’ Guide To The Galaxy’. And incidentally, the rest of the ingredients list includes a teaspoon of cinnamon, presumably powder, in case you were wondering, and the next bit reads as follows (and has started to transition to live-action):

(apparently it couldn’t deduce the spelling of “yields”).

Just to put this in context, this is naturally from H2G2 and regards the operation of the second greatest computer in all of space and time, Deep Thought, who started from first principles with ‘I Think, Therefore I Am’ and managed to deduce the existence of rice pudding and income tax before anyone managed to turn it off. It does this without any RAM incidentally. Is it just me, or is anyone else reminded of the bomb in ‘Dark Star’?

This is the second time, to my knowledge, Douglas Adams chooses to parody Descartes in the series. The first time is with the Babel Fish proving God exists and therefore doesn’t exist. This one involves Descartes method of doubting as much as possible until all he’s left with is the Cogito, id est, “I think, therefore I am”, and then using the Cosmological and Ontological Arguments for the existence of God to fill in everything he’s just rejected as open to doubt. He could’ve gone further, but didn’t. Isaac Asimov did something similar in ‘Reason’, where a robot on an orbital solar power station deduces that there is no Universe outside the station and that humans are brought into existence in the airlock when they arrive and are killed when they re-enter the airlock to leave. Incidentally there are problems with his presentation of the Three Laws in this story because it was written before he’d fully formulated them.

In terms of the two deductions above, Adams has a version of the Universe which strongly resembles the English-speaking world of the late 1970s, perhaps even the Home Counties, and Deep Thought is therefore able to deduce the existence of rice pudding relatively easily. In fact I think income tax is a more probable deduction than rice pudding, although that still involves the existence of what may be a uniquely human institution, namely money. As a side note, the idea that cinnamon exists is reminiscent of ‘The Dune Encyclopedia’, where the spice Melange, secreted by the sandworms of Arrakis and enabling humans who take it to fold space and travel between the stars without moving, an ability known here as  קְפִיצַת הַדֶּרֶךְ or Qephitzat Ha-Derech, turns out to be similar in composition to cinnamic acid, as seen at the top of this diagram:

Molecular structure of the spice Melange. Note the copper atoms in the porphyrin ring, conferring its distinctive blue hue

Hence at least in the Dune universe, a cinnamon-like substance does exist off Earth.

As mentioned a few posts back, Fred Hoyle used the Anthropic Principle to conjecture that the bonding energy of the carbon-12 nucleus was of a certain value. Starting from the first principle that organic, carbon-based life exists, he predicted the triple-alpha process. In the early Universe, almost all atomic matter was either simple hydrogen (protium – just a proton and an electron) or helium-4, with two protons and two neutrons. If two helium-4 atoms combine, they form a beryllium-8 atom, and if that then collides with a further helium-4 atom, carbon-12 is formed. In most circumstances, the probability of this happening is very low but it so happens that the energy of three helium-4 atoms colliding is unusually close to the energy of a carbon-12 atom, meaning that they are more likely to stay together than they would be otherwise. This is an example of the so-called “fine tuning” which appears to show that either a Creator exists or that we are living in one of an innumerable number of parallel universes where the conditions happen to be exactly right. By a happy “accident”, conditions in this universe happen to favour the existence of carbon, upon which life can be built.

This is an unusual path of reasoning that turned out to lead to a successful prediction and is therefore similar to the deduction that rice pudding exists in H2G2. It goes roughly like this:

1. I think, therefore I am
2. Physical conditions in the Universe must allow thought to occur
3. For thought to occur, organic life must have existed at some stage
4. For organic life to exist, carbon must be an abundant element
5. For carbon to exist, the triple alpha process must be favoured

There’s a humungous number of steps missing from that argument of course, but it’s a fair sketch of how you get from the Cogito to the strength of the strong nuclear force and the existence of organic life. Note that Deep Thought was not an organic life form, but in order for computers to be invented, organic life forms are assumed to be necessary at some stage.

I was once very impressed indeed by an a priori idea that seems to prove that the atmosphere of any roughly spherical planet must have at least two locations where there is no wind. This sounds very much like the kind of thing which could only be demonstrated by observation. One can imagine looking at endless detailed global weather charts and finding at least two spots on each of them which are completely calm, and then making the inductive inference that it was very likely always to be the case. However, this isn’t necessary and in fact the proof can be demonstrated by means of imagining you’re trying to comb a tribble:

exhibit in the New Mexico Museum of Space History
21 August 2017, 14:59:27
Own work
Stilfehler

Each of the hairs on a tribble can be thought of as arrows indicating wind direction. No matter which way that hair is combed, there will always be at least two points on the animal’s surface from which all the hairs radiate. Of course it makes more sense to give a tribble a parting or whatever, but the fact remains that there have to be two such locations, and that’s a topological truth. Extend this to a globe showing wind direction on any approximately spherical planet or moon, and the fact remains true, except of course that the atmosphere has depth. This, however, simply means that each individual layer must also have two still spots. It doesn’t work if the world has mountains on it high enough to leave the atmosphere because then the supposed stationary spots could be lined up to be where the air would be if the mountains weren’t there, and this means that a toroidal world is exempt from this fact. It also means it doesn’t apply to ocean currents unless there’s no land on the world. Therefore it already becomes possible to conclude from the premise that there are round planets completely enveloped in atmospheres that this is so without actually going there and checking them out.

Yesterday’s post on landlocked countries led me to similar conclusions, although they’re probabilistic and rely heavily on the idea that there are other planets with territorial intelligent life forms using a money-based economy on them. In fact that’s not entirely true. There are two sets of implied facts about such worlds, one relying on the existence of beings like us in those respects, the other not. We have already divided Mars, Venus and other worlds geographically into smaller areas, which are however not that relevant to this issue because there are no open bodies of liquid on those planets, but if, for example, Venus looked like this, and the land masses were divided up geographically, they would have certain predictable features.

I made the following claims yesterday about landlocked territories. They are likely to:

• Be arid
• Have extremes of temperature
• Include high mountains, perhaps near or on their borders
• Be located on the largest continent
• Contain the point furthest from the land on that continent

The last point is not in fact true of Kazakhstan, Bolivia or Paraguay, but it is true of the Central African Republic. Except for the third, these are all consequence of the physical features of lines on a map separating bits of land, although not below a certain number. For instance, Hispaniola simply has a line drawn down the middle of it separating Haïti and the Dominican Republic and I have no knowledge concerning where the highest point on that island is, although it’s obviously more likely to be in the larger country. And to test that hypothesis without foreknowledge, the Dominican Republic is larger than Hispaniola and therefore more likely to contain the island’s highest point. And indeed the highest point on Hispaniola, and in fact in the whole of the Caribbean, is Pico Duarte. The reason for assuming that landlocked states are likely to have high mountains near their borders is that borders are often placed in inaccessible regions where there isn’t likely to be much argument over resources.

Then there are the conclusions which can be drawn about landlocked countries which do rely on the current economic system and the way humans tend to behave under it. Landlocked countries are also more likely to be:

• Neutral
• Poor
• Reliant on natural resources more than manufacturing
• Totalitarian
• Have intolerant attitudes among their population

I explained the reasoning behind these attributes yesterday. They don’t apply across the board. For instance, Switzerland is mountainous and neutral but also rich and relies on financial services fairly heavily, although of course it makes Swiss Army knives and clocks, and presumably a lot of other stuff which my ignorance and cartoonish image of the country has failed to reveal.

It’s also possible to invert and go to opposite extremes with the first list at least. For instance, the largest continent is likely to contain the highest mountain, and in fact it does in terms of height above sea level, and likewise the largest ocean is more likely to include the deepest point, which again is so. Maritime and island countries are likely to have wet weather, have relatively little variation in temperature, particularly if surrounded by a lot of ocean as with Polynesian nations, and be fairly flat. Inverting the list of human characteristics doesn’t work as well, at least with island nations, and here I have Britain in mind in particular. They are likely not to be neutral (true), rich (true), not reliant on natural resources (not true – North Sea oil and gas come to mind, also historically coal and tin), be liberal democracies (this is only marginally true in our case) and have tolerant attitudes. It seems to some extent that in fact the same things are true of Britain at least as much as they apply to landlocked countries. It is the case that we have a moderate climate which is also quite wet, and that we have no high mountains.

The economies of island nations tend to be smaller, isolated from the global economy, dependent on shipping and therefore having relatively high prices for imported goods, but this really applies more to oceanic islands such as those of Polynesia rather than those situated on continental shelves. This island I live on is hardly one of the former. Nor is its western companion. As mentioned yesterday, landlocked states are somewhat protected by violent, ocean-related events such as tsunami and hurricanes,and conversely islands aren’t. Their infrastructure is therefore vulnerable. Again, this is one of the realities of a small, exposed piece of land in the middle of an ocean, though only on a planet with a particular set of meteorological conditions. Vast expanses of ocean are generally amenable to the development of tsunami and hurricanes on this planet, and a glance at Jupiter indicates that the latter are common elsewhere, but there might be globally frozen oceans with volcanic peaks sticking out of them for example, or widespread shallow seas.

The Hairy Ball Theorem mentioned above doesn’t apply to tori. This has an interesting consequence for oceans which could be considered toroidal in the sense that they include a range of latitudes where there are only small islands impeding their flow around the planet, because it means there can and probably will be both a steady current running all the way round and also winds able to build up speed without encountering obstacles. There’s a contemporary and a prehistoric example of this. The Southern Ocean exists today in this form, and the Tethys, which was tropical and subtropical, was in place for around 200 million years and still has traces today, although it’s no longer a continuous ocean.

I’ve previously stated that landlocked countries are likely to include high mountains, but this is somewhat misleading as it ignores continental drift. In fact, both Americas have mountain ranges on the Pacific coast caused by the continents moving in that direction and encountering the Pacific Plate. On the other hand, when two continents collide, the result is a mountain range far from any ocean, as with the Himalayas. The trouble is that it looked like I was thinking of a continent as a kind of spread out mountain, which isn’t how it is.

There are forty-seven island nations. Although the largest is Indonesia, which is bigger than Mongolia, that’s distributed over a large number of islands of varying size and it’s also continental, being in Eurasia and Sahul (the technical name for Australia as a continent as opposed to a country). The “U”K is the seventh largest of these and Great Britain the ninth largest island of any kind. Again deploying the rice pudding principle, the area of island nations is likely to follow something like the 80:20 rule, in that eighty percent of the area of island nations will consist of twenty percent of the nations, or something close to that, and also eighty percent of the area of all islands will consist of twenty percent of the islands. It won’t be exactly that, but it should be close. For these forty-seven nations, that means that the nine largest ought to have four-fifths of the area. These are Indonesia, Madagascar, Japan, the Philippines, Papua, Aotearoa/New Zealand, Iceland, the “U”K and Cuba (Ireland is next on the list). It isn’t practical to do the same for physical islands because there are an indeterminate number. These islands taken together have an area of 4 460 372 square kilometres, which suggests that the remainder will have a total area close to 900 000 km². In fact their area adds up to 4 851 659 km² if I’ve calculated that correctly, which is fairly close. The same principle might be applicable to population and population density. Indonesia is again the most populous of these nations, the “U”K being fourth, and the most densely populated is Singapore, which is of course a city-state. The most sparsely peopled such nation is Iceland, although Kalaallit Nunaat/Greenland is even less densely populated but doesn’t quite count as an independent state.

Island nations are of course very subject to climate change, such as the increased acidity of the oceans causing erosion of coral atolls and reefs, rises in sea level and increased occurrence of hurricanes. Some of them are at risk of disappearing entirely, but others, maybe surprisingly, are increasing in size because of it. They tend to be more politically stable than continental states but are more susceptible to invasion by them. This seems not to be true of Britain although some of our reputation for not having been invaded is due to an economic approach to the truth, since it’s also been said that England has been invaded more than six dozen times since 1066, for example the Glorious Revolution of 1688. These states are also often microstates, which means they can’t take advantage of economies of scale.

There would seem to be four different types of island states, depending on whether they’re based on archipelagos with a number of islands of similar size or consist of one larger island or a single island, and whether they’re continental or oceanic. Ireland and Britain are obviously both predominantly single island states and continental, and being continental makes quite a big difference. One perhaps surprising thing about Pacific islands is their linguistic, and therefore presumably cultural, homogeneity. It might be expected that isolation leads to difference, but in fact it seems not to, even though unique ecosystems do evolve on them.

Then there are maritime states. Technically, France and the “U”K have the most borders, most of which are maritime in both cases, because of their dependencies overseas. This is followed by Russia due to its size. Countries with single land borders tend to be on islands, such as Ireland and us, although Canada is a major exception. The characteristics of maritime states don’t seem to be as thoroughly explored as those of island and landlocked states.

Moving away from the sea and land issue brings one to the four-colour theorem. This is remarkably irrelevant to cartography, but involves the proof in the ’70s that any flat surface map or globe could be coloured with at most four colours. This might be expected to have big consequences for politics but oddly, it hasn’t. It is relevant to the number of frequencies needed to operate mobile ‘phone masts though. It doesn’t work for maps with non-contiguous territories such as Alaska and the Lower 48, or presumably the traditional counties of Wales and England, which have many enclaves and exclaves.

Ultimately, all of these kinds of considerations seem to be to do with applying mathematics to a few well-established facts, so in a way they’re all just bits of science. Two questions therefore arise. One is whether everything can be deduced from facts and principles about which it’s possible to be certain. Another is whether there’s an important distinction between the human-related aspects of these facts and the physical ones. Do we have enough control over ourselves, and do governments have sufficient flexibility, for these facts not to be inevitable? Is there something about human behaviour that just will not alter which leads, for example, to landlocked states being more likely to be totalitarian? Is there disruptive technology or other ideas which can change that?

I’ve used geography here to present this issue, but there are other areas where it applies, so to close I want to return to the issue of rice pudding and income tax. Deep Thought was able to deduce the existence of income tax from first principles. This means that money is inevitable. This is actually part of quite an oppressive ether pervading the H2G2 universe, because we know, for instance, that it’s possible (or rather impossible) to deposit a penny in one’s own era and find that at the end of time the cost of one’s meal at Milliways will have been paid for. This means that usury will always exist, and this makes capitalism as we know it a law of nature. There’s no escaping the flawedness of all lifekind for Douglas Adams. This might be connected to the certainty of death and taxes, but the taxes in question there were not income tax, which didn’t exist at the time. In a way, though, this could be seen as hopeful from a left wing perspective to some extent, because it means money will inevitably be pooled for the common good. The contrary view, of course, is that it’s theft. However, the idea that income tax can be deduced to exist from the Cogito does seem to be more feasible than the idea that rice pudding can, because income tax seems to be about numbers and science, but then so is rice pudding.

In order to exist, rice pudding needs milk and cereal. More specifically, it needs rice. According to the recipe Deep Thought came up with, it also needs demarara sugar and cinnamon. Of all these ingredients, the most likely one to be widespread in a Universe with organic life in it is sugar, although it may be glucose rather than sucrose. Milk is strictly speaking the nutrient secretion of a particular clade of Earth animals, but we are fully aware that EU nomenclature notwithstanding, “milk” needn’t mean milk, and in fact has a long tradition of use in other ways, as with almond milk and latex-containing plant sap. There’s coconut milk and a number of “cow trees”. Galactodendron of Central and South America yields a latex which is high in protein and can be used to make cheese and ice cream. We’re actually fine as far as milk is concerned, as an opaque white nutritious fluid is very common and found from all sorts of sources. It does, however, seem to depend either on the existence of seed-bearing plants or animals who secrete it.

Rice is a bit dicier. Although it happens to be a grass, there are grain-like seeds and fruits from other sources. This is important because although large areas of grassland are common today, in the fairly recent geological past grasses were just another species of plant with no particular dominance which coexisted in more diverse ecosystems, although even then they could presumably be cultivated, and there are non-gramineous cereal-like things like buckwheat and quinoa. Rice, however, is fairly distinctive. Porridge is not the same thing as rice pudding, and on the whole rice pudding is considered sweet.

Hence the dependencies of rice pudding seem to be the existence of seed plants. Although milk can be from an animal source, the animals humans actually exploit for it are grass-eaters, so it kind of depends on the existence of grass in two separate ways. Even three, if the sugar is from sugar cane. It is conceivable that rice pudding might be like gin & tonic, in the sense that according to the epic adventure in time and space it’s just called something like that everywhere but doesn’t refer to the same drink. However, this can’t be quite true because we see a list of ingredients, as specific as “pudding rice”. There’s also the issue of rice pudding being deduced if it only exists on Earth, because although Deep Thought knows that a greater computer will be built one day, it presumably doesn’t know the details or it would be able to predict that its own task would be unsuccessful. Therefore it seems likely that rice pudding does exist elsewhere in the Hitch-Hiker universe. It is also the case that variants of rice pudding exist all over the land surface of this planet, but it’s less clear to me whether it’s been invented independently on more than one occasion.

I’ll close, then, with this. Income tax seems to be a more likely candidate for deduction than rice pudding, but is it? Is it just that the use of maths-like concepts applies more easily to the idea of tax than it does to rice pudding? Is there a stereotypical gender-rôle bias here? What’s it about?