Rix

Rix is a small planet, about eight hundred light years away from Earth, orbiting a K0-type star at a distance of 0.70 AU. Due to geological conditions, Rix has extremely large areas of tsingy formations, with much of the remaining land still being limestone based as well. The oceans are fairly shallow; often the tsingy formations, maintained by reef-building organisms, rise above them.

Astrometrics
The Rixan system is, as previous mentioned approximately eight hundred light years away from Earth, on the fringes of the Orion Arm. It contains a mere three planetoids, none of them very large; the outer planets of the Rixan system have been stolen away by a rogue star. Zexania (the star of the Rixan system) is, meanwhile, nearing the end of its life as a main sequence K-class star, and the native sophonts are desperately trying to gather the necessary resources to reinvigorate their star.

Previously, the orbit of Rix was so elliptical that nothing except extremophiles could survive. Due to the gravitational pull of a passing rogue star, though, its orbit became more circular. Relatively soon after, extremophiles evolved into multicellular life, or went extinct (in the cases of a few bacteria-like organisms adapted for a freezing existence; their spores finally died due to an inability to cope with the constant tropical temperatures). By this time, Rix was very old—many radioactive isotopes had already decayed, and that resulted in the atmosphere having a high percentage of noble gases, especially the heavier ones like krypton and xenon.

Rix has one natural satellite. In addition, the Trax have created several large space stations that orbit Rix. These are not large enough to have any effect on the tides. The single moon of Rix is named Epraz, and is about the size and density of the Earth’s moon.

Atmosphere
The atmosphere of Rix is toxic to Earth life. Most of the atmosphere is nitrogen and oxygen, with substantial amounts of noble gases (the frequency of noble gases is in large part due to the amount of time several isotopes have had to undergo radiological decay). Relatively large amounts of carbon monoxide result in rapid poisoning of Earthly organisms; Rixarn life is immune due to its different oxygen-carrying molecules. A large amount of carbon dioxide keeps the planet very warm, despite the small size of its dim star. Because of the makeup of Rix's atmosphere, atmospheric density is much higher than on Earth.

The high concentrations of noble gases in Rix's atmosphere mean that its auroras are significantly brighter than ours. Around the North and South pole, the auroras can be bright enough that plants will continue photosynthesizing during the polar night, though the rate of photosynthesis drops dramatically during polar night. As Rix has analogs to rainforests on its poles, this creates what is widely seen as one of the most beautiful displays in the area—a rainforest at night, illuminated by a brilliant aurora.

Geology
Rix is a planet that is, at least on the surface, exceptionally metal poor. Very few deposits of iron-bearing rocks and minerals can be easily found and mined; a thick layer of limestone, deposited by dead organisms when most of the planet was covered in shallow water, is the dominant rock formation. Aluminum is more common than iron, though still fairly rare. Copper is abundant in comparison to Earth; copper is also one of the main metals used in Traxarn technology due to how common and easily available it is (copper ore mines on Rix, due to chance, tend to be closer to the surface and easier to excavate than iron ore mines), and is also the basis of Rixarn blood.

The main exception to the metal-poor rule is around volcanic areas, where lava often contains iron ore. As most volcanoes on Rix are underwater, these areas often support communities of organisms with hemoglobin as their oxygen-carrying molecule.

The interior geology of Rix is very close to that of Earth’s, with the only difference being slightly different ratios in the thickness of layers; Rix’s inner core is larger, resulting in a stronger magnetic field.

Geography
For the most part, Rix is ocean—the planet has three large landmasses, and two massive archipelagos.

Lazax is the largest Rixarn landmass, located on the Equator and straddling Rix’s Prime Meridian. For the most part, it is rocky semidesert, inhabited by predatory, ambulatory “plants” that prey both on each other and on various animal species. As usual for Rix, the animal species have adapted to dry land by secreting a waxy covering, similar to that of the waxy monkey frog (Phyllomedusa sauvagii). Other biomes include a plains-type biome (albeit one where, in addition to grass-like plants, an array of tendrils stretch towards the air in an attempt to capture migratory flying creatures which use the plains as a stopping point), and a cloud forest.

Surrounding Lazax is a shallow sea, colonized by a close relative of Eoterraphyta that forms colonies, and secretes a limestone covering. These colonies create large spires, which can reach above the water; several species “air coral” colonize the spires and filter out organic particles from the air.

Isguthus is the middle continent, and located in the North. It is covered in temperate rainforest, and is practically dripping with moisture. For much of the year, it is night on Isguthus, but the aurora provides enough illumination for plants to continue photosynthesizing, so the rainforest does not experience dieback—though there is only enough light for plants to keep their most basic functions running. The plants aren’t actually breaking even, either; they’re merely producing enough energy that going into hibernation and losing all their leaves isn’t worth it.

The smallest continent is Gurwath. It is a wet, tropical location, with most of the continent under sea level. Due to these conditions, the soil contains several evaporate minerals, making it difficult for plant life to grow. The plants that do grow are hardy plants, which excrete salt through the undersides of their leaves—a process that has the side effect of making their leaves unpalatable to most organisms.

The two archipelagos are referred to as Pretal Lowisk and Pretal Wasik ("Pretal" is the Traxan word for "group"). Pretal Lowisk surrounds Lazax in a ring, and forms the border between the continent’s shallow seas and the open ocean. Pretal Wasik is a group of islands near the South Pole, and home to a wide variety of endemic wildlife, similar to the Galapagos Islands, Madagascar, and Australia all rolled into one.

Biology

 * see Rixarn biology for more information

Rixarn biology is, much like Earthly biology, carbon-based, with roughly similar amino acids and proteins used for genetic coding. However, due to a different chemical makeup of Rix, Rixarn life has certain chemicals taking places that are taken by other chemicals in Earthly life.

As mentioned before, no terrestrial Rixarn life can survive with hemoglobin as a oxygen transporter (too much carbon monoxide). Since copper is relatively common on Rix, and carbon monoxide is present, hemocyanin is the main oxygen transporter. A few organisms use other transporters, but they are extremely rare. For the most part, these are marine organisms that live in places where they are isolated from carbon monoxide, such as the deep ocean. In such oxygen-poor conditions, hemoglobin is actually favored due to how effective an oxygen transporter it is—the concentrations are just before the point where hemocyanin is more efficient than hemoglobin.

Photosynthesis utilizes the pigment phycocyanin and chlorophyll a, rendering plants a greenish-blue. Like Earth plants, photosynthetic pigments are contained in chloroplast-analogues, which are descended from symbiotic single-celled organisms. Due to Rix’s low light levels, however, chloroplasts haven’t developed much in the way of motility: Photosynthetic organisms don’t really need chloroplast motility to protect themselves from excessive light on Rix. A few organisms, however, are in sunny enough areas to require chloroplast motility.

Basal groups of terrestrial macro-organisms on Rix fall into three main categories: Terraphyta, Xenoserpentes, and Geotergum. In Rixarn biology, these are considered the three primary forms, with most other life descended from them. They weren’t the first organisms, of course, but they are the oldest fossilized macroscopic ancestors of extant Rixarn life.