Homeworld - Xendoria

Their homeworld Xendoria, which orbits close around a blue star, was formed when the universe was about 10 billion years old. The planet is constantly bombarded by solar radiation and subsequently has no atmosphere on the surface. For example, the closest Sol system comparison is Mercury. Additionally, the planet also has a frozen core and is geologically inactive. Fortunately for lifeforms such as the Xeno’dorians, there is a subterranean cave system which stretches underneath the entire planet’s surface. Within this cave system, there is an air gap, typically 30 kilometers in height from top to bottom, which is also shielded from radiation due to the thick rock insulating the cave from the planet’s surface.

These cave systems provide a safe and livable environment. As heat from the planet's surface spreads towards the core, it encounters the cave and is transferred as infrared radiation through the air. Similar to how Terran plants utilize visual light, Xendorian plants evolved to use infrared light to make energy and oxygen. The plants also emit visible light as a byproduct of their metabolism. Despite the decreased efficiency of infrared photosynthesis, the cave systems are full of plants, with thick and dense forests composing vast swathes of the underground ecosystem.

Regarding the hydrosphere, the waters of Xendoria consist of roughly 19% hydrogen chloride. During the day water evaporates, rising to the ceiling of the caves. At night, when the ceiling cools down, water condensation results in a nightly rain. There are many rivers and lakes on their home planet, which drain into the oceans. These oceans have many radioactive isotopes, enough that Cherenkov radiation causes them to faintly glow. This Cherenkov radiation is due to the beta decay of radioactive isotopes, wherein the beta particles accelerate past the local speed of light, and their interaction with water molecules as they decelerate causes visible light to be released. Not only that but the radiation in the oceans is also harvested by algae to produce energy. Regarding other ocean life, it is vaguely similar to the marine life forms found on Terra. Another comparison is that the oceans are deeper on Xendoria than on Terra. Interestingly, the cave systems are actually a result of the hydrosphere carving them from the rock through the continuous daily cycle of erosion by rain over billions of years.

Seasons on Xenodoria follow a pattern similar to Earth’s, though they’re more extreme thanks to its 25° tilt. Generally, they can be divided into 4 seasons that evenly divide the year. The effects of each season are dependent on latitude as well as depth. For example, the tropical regions of Xenodoria only experience 2 seasons, wet and dry; but the temperate climates experience a summer, spring, fall, and winter.

Tropics

The tropical regions of Xenodoria lie between ±25° latitude. Temperatures year round remain the same with only small fluctuations as you near the temperate climates. Because of this, the climate is uniform with the only notable difference in areas being the type of wildlife that inhabit them. Because of this, the biosphere is also the most diverse compared to the other regens of Xenodoria. This is also the home to the first Xeno’dorians making it their “native” climate.

Soul valley

Soul valleys are full of toxic elements like lead, lithium, beryllium, lanthanides, actinides, and Sandy gravel. This causes them to be lifeless and highly radioactive. From over the years rivers of Radon gas has formed. henceforth Xeno’dorians do not live in the soul valleys.

Xendoria’s star is fairly unique and harsh compared to the gentler main sequence stars most life hails from. On top of being a blue giant, it is also a Wolf-Rayet star. These rare stars are formed with lower amounts of hydrogen to start with, usually as a result of being born from the leftovers of supernovae. They’re primarily composed of carbon and burn incredibly hot and bright. This does not help Xendoria as it is also fairly close to its host star making the surface blindingly bright, at least to human eyes. However, if you were ever caught on its surface during the night, you would be greeted by one of the most awe-inspiring night skies anywhere in the galaxy. The star is saddled firmly inside of a nebula, which in turn fills the night sky with many colors that are reflected back from the space dust thanks to the light of the brightest star for lightyears.

Xendoria and its star system have a rather interesting formation story, and it used to be a part of a binary neutron star system. After many millennia, the stars grew closer to one another and collided, resulting in their destruction and the spread of many heavy elements through nearby space and onto orbiting planets, including Xendoria itself. This left the planet irradiated, and alone, drifting into space. At this point in Xendoria’s history, only simple microbes existed, which were able to survive off the sparse and dwindling energy resources. Despite the cosmic odds, Xendoria managed to get recaptured by another star, the aforementioned Wolf-Rayet star, with the help of a gas giant and other orbiting bodies. This new energy source eventually powered the evolution of the resident microbes toward the development of complex and multicellular organisms, culminating with Xeno’dorians.