The Worldbuilding of Jupiter

**JOVIAN SOCIETY**
One species of Hunter is sapient and has a remarkably advanced technological civilization. The key to the Jovian's success is an immensely complex digestive system which, when properly manipulated by a mind that is in some ways vastly superior to that of a human, can manipulate matter in ways that would make a 3D printer seem obsolete. They can manipulate water ice into telescope lenses, animal and plant tissue into tools. Their cities are formed by domesticated floaters holding up cooked animal tissue "houses" which provide shelter and living space. Particularly large cities may be held up by more than one floater. The floaters are kept alive and defended from other hunter species, because otherwise their cities could sink. They even use technology similar to steam engines: organic tissue is dried out and converted into fuel which is decomposed inside water ice fireboxes, producing heat which boils ammonia. The content of metal and rock is, for all intents and purposes, exactly zero, and they will NEVER fly in space on their own.

The Jovian eyeball is an incredible biological mechanism. Unlike the four channel rods+cones of human vision, the Jovian eyeball senses the spectrum of photons and records that as color. Therefore, with vision alone, the spectrum of light within the visible range can be sensed. Their sensitivity to light *would* be much worse than humans due to this, except their eyes are *huge*, nearly a meter across.

Unlike humans, which have had a technological society for a much shorter time than the whole of their history, it seems that these Jovians have been semi-technological for more than half a million years, their manipulator systems being the result of natural selection suited towards semi-technological society, and perhaps a few stretches of nasty eugenics over the past few hundred thousand years.

While Jovians have spread all across Jupiter, the immense size of the planet means that there are many vastly different ethnic groups, cultures, and indeed wholly different species of sapient Jovians.

For the rest of this look at the world of Jupiter, we will hear from the (translated) point of view of the Jovians themselves.
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**JOVIAN BIOLOGY**
The three main classes of life:
-Sinkers: Small organisms which ride currents and survive by reproducing before they get swept into the pressure cooker depths.
-Floaters: These are huge, kilometer scale, dark organisms which absorb sunlight to heat themselves up and filter out helium from their insides to function as huge balloons.
-Hunters: These are animals which hunt the floaters. Some simply consume them and eat them, while others suck out their supplies of pure hot hydrogen. Some are just small floaters, others are winged birds which can fly under their own power in addition to floating with hot balloon-like insides.

**JOVIAN NAVIGATION**
Travel between settlements and cities is a dangerous endeavor taking many dozens, even hundreds, of Callisto orbits, and it should never be done alone. It is wise to take a Floater along with you for shelter and rest, and you must have a very good navigator. Because settlements will necessarily drift over time over longitudes, settlements are almost always kept, either by manual labor or by steam engine propeller, at the exact same latitude, as measured against the stars. Therefore, navigation is done by travelling to the correct latitude line, and then flying east or west an indeterminate direction, possibly further than the circumference of Jupiter if you pick the wrong direction, and keeping a keen telescopic eye out for signs of settled structures. For settlements that have not been visited in a very long time, it may be impossible to find them except by spiralling through the entirety of Jupiter, checking each latitude spanning horizon to horizon, before moving north or south. In order to keep roughly accurate longitudinal information between settlements, mail carriers between settlements regularly take precise stellar Right Ascension measurements against the Sun, and run the numbers to figure out how far apart the longitude is. This is impossible along the jets separated belts and zones, as settlements not far apart in latitude may be travelling very quickly away.

In the southern hemisphere, the South Celestial Pole is found by taking the line between Adara and Canopus, and following it further until it crosses the line between Miaplacidus and Alpha Doradus. In the North, the pole lies approximately between Eta Draconis and Altais.

Due to the difficulty and unpredictability of finding another settlement, settlements tend to get very large and very isolated.

**JOVIAN ASTRONOMY**
There are four planets in the solar system. Ours, Jupiter, is the closest to the Sun, and it is the largest. Saturn's the next largest, and its ellipse shape in the night sky observed by those of us old enough to remember the last opposition is caused by a bright system of rings made up of the same material as the nasty tasting clouds that explorers have found below the brown clouds, and the same material as what seems to cover the outer three major moons. Saturn has only one major moon, and it seems to have an atmosphere similar to some of the dwarf planets. Uranus and Neptune are dim blue planets, about a quarter the size of The Jupiter. The blue comes from a high concentration of the kind of air we exhale. Uranus has no major moons, Neptune only has one, which orbits backwards.

Inferior to Jupiter are four to six dwarf planets, depending upon who you ask, which are mostly larger than the major moons. The fast one Mercury orbits in only 211 days, and is just about the size of Callisto. Then there's Venus and Terra, which are 40 times as heavy as Ganymede and very hot. Terra is covered in molten ice and has a major moon of its own. Venus is the hottest of the dwarf planets. Terra and Venus have atmospheres made of rare heavy gasses like Nitrogen and Carbon Dioxide, Hydrogen and Helium are too lightweight to be held down by the minuscule gravity of the dwarf planets.  Mars is only four times as heavy as Ganymede and not a whole lot bigger. If it has an atmosphere, it's not a very thick one.

Between Mars and The Jupiter is a gap where only airless minor planets live, excepting three or four very small dwarf planets Ceres, Vesta, Pallas, and perhaps Hygiea. The minor planets are few and far between, but still vastly outnumber the inner dwarf planets. About 15 or so are known. The inner dwarf and minor planets are composed of an unknown material that remains solid at extremely high temperatures, which seems to be very similar to what Io is made from.

To get an idea of how hot these dwarf planets are, consider that comets are what happens when icy bodies found around The Jupiter's orbit plunge deep into the inner solar system and start to boil.

There's one dwarf planet between The Jupiter and Neptune, called Chiron. There are several other minor planets around as well, including two distributions ahead of and behind Jupiter in its orbit, of which 30 are known.

Beyond Neptune there are three dwarf planets known: Haumea, Pluto, and Eris. It is possible that there are many more dwarf and minor planets beyond Neptune.

The Jupiter itself is host to nearly 80 minor moons. Four of them are the "dwarf moons," so named because they are close enough to appear to be larger than they really are. Then there's the four major moons, each of which is the size of a dwarf planet. The rest are minor moons, probably captured minor planets, that orbit far away over the span of hundreds of Callisto-months.

The Sidereal orbits of the moons are marked by their passage south of the Pleiades, the Seven Overseers, a cluster of bluish stars which are easy to spot in the night sky.

**JOVIAN ASTRONAUTICS**

The notion of flying higher than the highest clouds and travelling in space is quite attractive for some writers of fantasy. Exploration of the structures and possible native life forms living on Saturn, Uranus, and Neptune. Some have even suspected that the ingredients for life can be found on the dwarf planets. Unfortunately, there is no known mechanism for the propulsion of a hunter into space. Above a certain height, we can not stay afloat, we can not breathe, and we can not fly. Even if we could, in order to stay up in space like a moon, you would have to travel at a speed of 42 kilometers every second, thousands of times faster than the fastest living thing. To escape The Jupiter and travel to the other planets would require even more excessive speeds, and you'd have to hold your breath for years at a time.

Still, we know that space travel is possible in principle. Within the past year or so, astronomers have found very tiny moons orbiting among the major moons, which seem to be able to change the speed and direction of their orbit on their own. They are made of an unknown material, and are much smaller than even one of us, but many astronomers are sure that these must be some kind of space animal. They may come from the dwarf planets in the inner system, where sunlight is so high that they wouldn't have any problem absorbing and storing energy for space travel.

**JOVIAN SETI**

While many astronomers consider the notion of space animals to be totally absurd, others are convinced that the motions of some of these exotic minor moons can ONLY be explained by some kind of intelligent direction. The second minor moon to show these unnatural motions was observed travelling on a flyby trajectory of The Jupiter, then it entered an elliptical nearly polar orbit. It orbited a few dozen times before *changing its orbit* and crashing into The Jupiter and burning up. Over the next few years, dozens more such "space animals" have been found. A hypothesis for their method of propulsion is that they use huge, powerful jets, which burn as hot as the sun itself. As absurd as this may sound, remember, the dwarf planets are made of a material that can withstand extreme temperatures. Perhaps they are made from something similar to pure carbon. There seems to have been an increase in the amount of space animals observed over the past few years.

Some astronomers believe that the space animals may be intelligent, and are trying to consider ways of contacting them or notifying them of our existence. While some sources of bright chemical luminosity are being developed by chemists, it is unlikely any space animal intent on observing The Jupiter would notice the difference between them and lighting strikes. We have also considered producing massive structures that would alter the structure of The Jupiter's clouds over a large enough area to be clearly artificial. Other thinkers believe that only bad things can come of alerting space animals to our presence--they may be hunters or slavers. And of course, there are those who think it would all be a waste of time and money.
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The preconceptions that the Jovians had about what our spaceships were and what they were doing are always fascinating. When we finally did start sending probes and drones down into Jupiter and we discovered an intelligent technological civilization hiding right under our noses in our own backyard, it was a revelation. Here were beings so incredibly different from us in environment and capability and biology and psychology, and yet there was still so much we had in common with them. It's too early to say, but one day a Jovian might just fly on a spacecraft to the other planets...