100th Millennium Wiki
100th Millennium Wiki


Athena is an average-sized frigid ice giant situated in the Lochia System of the Charybdis Galaxy. It is the seventh planet of it's respective system, and the most researched out of the eight planets in it's planetary system. It is one of the first ten discovered gas/ice giant worlds that have a complex ecosystem beneath it's clouds.

Athena is a highly prominent tourist destination within Karasia region, with many billions of tourists coming to visit the planet to see the complex ecosystem that resides within the atmosphere of Athena. Athena is noted as one of the "100 Wonders of Karasia", a list of the most unique places in all of the Karasia region.

Athena is home to only one atmospheric city, which has been named the Kronos City. While the only one, the city is absolutely massive, measuring roughly a thousand kilometers in size. This city has a population of around one billion inhabitants, mostly situated in dense urban areas, while some inhabitants have a more rural and idyllic lifestyle in specialized farming sectors.

Athena has 56 moons, but only two of them are spherical. They have been named Prometheus and Xantheon. Xantheon even has exotic multicellular life on it's surface, and is of interest to many scientists for it's abnormally fast evolution. A very dim set of rings orbits Athena, which are most of the time completely ignored by any tourists.

In the far past, a major planetary object collided with Athena, causing it to have it's abnormal and unique axial tilt of 97 degrees.

Athena's main tourist attraction is it's diverse and complex ecosystem in it's atmosphere, extending even to the outer atmosphere. Many creatures of all shapes and sizes roam the deep and thick clouds of Athena. These lifeforms are vastly different from terrestrial organisms. Many creatures utilize alien ways to gather chemical elements, such as energysynthesis.

Kronos City

The near-center of Kronos City

The Kronos City is the only urban center situated on Athena, located near the equator as a large-scale domed metropolis floating in Athena's outer atmosphere.

The dome of heavily pressure-resistant glass is required to protect against the deadly atmosphere of Athena, and also it's immense winds, which sometimes blocks entrances to the Kronos City as a result of the rapid storms that can happen on Athena.

The shape of Kronos City is spherical, with the average height being two kilometers and diameter being around a thousand kilometers, dwarfing even the largest atmospheric cities on most gas/ice giants.

In the ceiling of the dome, many airlocks exist, which are used for ships to primarily travel in or out of the city. The average monthly count of ships leaving and entering the city is around a million, as Kronos City is a fairly popular area for tourism.

The Kronos City has a population of a billion inhabitants, mostly being the Aquelis or Khadoor. These inhabitants are scattered throughout the many skyscrapers of Kronos City, with many adapting a rural and idyllic style, farming many of the smaller creatures present in the atmosphere of Athena in dedicated farming sectors.

Moons & Rings

The two spherical moons of Athena

Athena has a set of 56 moons in total, over half of which are less than ten kilometers in size and only two are spherical. Most of the dwarf moons of Athena have thought to have been captured asteroids. Two spherical moons orbit Athena, named Prometheus and Xantheon. The moons orbit along Athena's orbital plane, which means they share their parent planet's severe rotational tilt.

The first spherical moon, and the 36th moon, Prometheus is a frigid icy world covered in a layer of water-ice with a shallow, lifeless subsurface ocean below, blanketed by a pink atmosphere caused by the absence of argon.

The second spherical, and the 42nd moon, Xantheon is an unique one, having it's own set of large rings, caused by a collision with another large moon in the past. Xantheon has a high amount of hydrocarbons, most of them concentrated in seas. The absence of organic compounds has given Xantheon a fully-fledged, complex ecosystem with exotic biochemistry.

Other moons worth mentioning are Thealia, an asteroid moon around 54 kilometers in size that orbits Athena from a distance of a thousand kilometers, and is soon passing the roche limit, and will be destroyed. An other unique irregular moon is named Fortress, and is essentially an asteroid turned into a fortress of defense around Athena.

Athena has a system of rings which is the least famous out of any ring systems in the Lochia System. The rings are extremely dark, reflecting less than 2% of the radiation that strikes them, and are mostly lacking in dust due to Athena' extended thermosphere. They are thought to be young, less than 600 million years old, and likely are the remains of small moons that were destroyed by collisions. The rings orbit along Athena' orbital plane, meaning that they experience the same extreme rotational tilt as their parent planet.

Orbit & Rotation

Athena orbit it's parent G6.5 V star, Lochia at a distance of 8.5 AU, in a nearly spherical orbit with almost no eccentricity, which is rare for most planets. As a side effect of Athena orbiting so far from Lochia, it takes the planet 29 years to complete a singular orbital period around Lochia.

Athena is an unusual world in that its axis of rotation is almost parallel to the Lochia System's natural orbital plane. Due to this anomaly, the planetary poles receive more light from the sun than the equator. The cause of this unusual tilt is thought to be from an impact between Athena and another protoplanet early in the Lochia System's history. The Athenian magnetic field is dramatically offset from the planet's center of mass and not aligned with its rotational axis.


Athena has a climate with extreme seasonal variations due to it's unusual axial tilt. As a calmer than average ice giant, the average windspeeds on Athena are 400km/h on average, with some storms having windspeeds that can go up to 2000km/h. Athena has a global temperature -125°C, with the poles sometimes being a hotter and equator being colder, as a result of Athena's abnormal axial tilt.

Internal Structure

A simple and basic diagram showing the internal structure of Athena

Like ice giants, Athena is composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. As opposed to gas giants, helium and hydrogen make up only about 20% of Athena's mass.

Athena, like all ice giants has a rocky core composed of silicates, iron and nickel at their center. This core only accounts for a fraction of the total planetary mass of Athena however. The internal structure is composed of three distinct layers.

  • Atmosphere: An atmosphere containing hydrogen, helium and methane gases surrounds the mantle. This atmosphere accounts for a significant portion of Athena's radius but because of its low density it increases the total planetary mass by only a small amount. The outer regions of the atmosphere contains clouds, band structures and storms similar to those found mostly in gas giants such as Aurantia.
  • Mantle: The bulk of the planet is usually located in the intermediate layer, which is referred to as mantle. The mantle comprises an extremely dense and hot mixture of water, ammonia and other volatiles. In this layer pressures can reach up to several hundred Gigapascals, which accounts for the unusual properties of the fluid encountered at these depths, like increased solubility and electric conductivity.
  • Core: The core of Athena probably only accounts for 20% of the radius of Athena, and only about 0.55 Standard Terrestrial Masses. With gravity of all the outer mantle and atmosphere, regions in the core experience a pressure of about 8 million bars, and have a temperature of 4700 °C. The core of Athena has a density of about 9 g/cm3, which makes it about twice as dense as the average density of an average terrestrial planet.


Athena is host to a complex and highly diverse ecosystem residing all the way from the near-bottom of it's atmosphere to the outer cloud layer. All life on Athena is carbon-based, like most lifeforms in the universe. The organisms do, however, use ammonia as a solvent, instead of water which is usually thought to be much more common as a solvent compared to ammonia. Life on Athena inhables hydrogen and exhales methane, which is common on gas giants with life.

Since nearly no starlight penetrates the thick clouds and reaches the most life-filled regions, photosynthesis cannot take place in any way or form. Instead, living organisms obtain their energy by two ways. The simplest and most prevalent method is kineticsynthesis, in which life obtains its energy from the environment by converting the kinetic energy of rapid winds into organic chemicals such as acetylene, ethylene, and ethane. This is made possible by microscopic organelles, which are comparable to cells seen in most animals. This process is common throughout the universe, with other gas giants with life such as Taranis being entirely reliant on kinteticsynthesis. The process also necessitates the presence of hydrogen and methane, both of which are abundant in Athena's atmosphere. Many species of predators, parasites, and detritivores, on the other hand, do not generate their own energy.

The secondary way of getting organic chemicals like acetylene, ethylene, and ethane is energysynthesis, which is also the rarest way of getting organic chemicals. This process involves a creature using it's tiny organelles to convert the energy from lightning bolts to organic chemicals through extremely complex chemical reactions. This is more common in the lower layers of the atmosphere however, where lightning is way more prevalent than in the upper layers.

Athena has few different habitats in comparison to otherwise vibrant and diverse terrestrial worlds, and as a result, its life is far less diverse, while being vastly more numerous. Because natural barriers such as oceans and mountains are nonexistent, almost all species can be found almost anywhere on the planet. This is due to the fact that changes in latitude do not result in temperature variations, as all heat originates deep from the planet's interior. Because of the planet's rotational flatness, there is a tiny increase in gravity at higher latitudes, although this does not effect life sufficiently to account for what could be termed a distinct habitat. However, latitude still generates two distinct biomes which are zones and belts.

Zones and belts are comparable to rain forests and deserts in several characteristics. When the wind is blowing upwards, zones form. They appear as larger, lighter stripes in the planet's atmosphere due to the surface ammonia clouds, and they are home to the bulk of the planet's life. The ascending wind carries nutrients from below and aids creatures in staying afloat, resulting in a thriving ecosystem. Belts, on the other hand, look as dark, narrow areas with strong descending wind currents that pull nutrients and living organisms down to the planet's interior. As a result, belts are Athena's primary natural barrier, although that doesn't stop animals from passing over them when necessary.

A vertical separation of biomes is another option. Within the range where life is prevalent, temperature and pressure fluctuate dramatically, resulting in layers with considerable variations in a species composition. Some creatures have evolved to survive in the planet's upper layers, which are colder and less dense, while others have evolved to live at high pressures and temperatures closer to the planet's core. There are also those which can live across both habitats, smoothly transitioning between them when necessary. As a result, Athena's diversity of life is related to changes in depth rather than latitude.

Origin of Life

The origin of life on Athena has been heavily debated by scientists, whether the life evolved on planet Athena by itself through abiogenesis or was brought on the planet by a comet through panspermia. Many other theories have been created, such as the theory that Athena was seeded with life by an alien species. Very little is known about the history of life on Athena since all fossil records are nonexistent. The current most accepted theory is that of panspermia. This states that life originated from microorganisms or chemical precursors of life present in outer space and were able to initiate life on reaching a suitable environment.

Classification of Life

Appearance Classification

Tenctiliou is a branch of lifeforms present on Athena that have a significant amount of their body being various tentacles and tentacle-resembling limbs. Tenctiliou are only limited to floater, scavenger and hunter organisms, with no tenctilious sinkers being discovered to date.

Waleria is a branch of organisms on Athena that bear a significant resemblance to the aquatic creatures known as whales. They are usually large in size and the rarest branch, commonly limited to floaters and rarely hunters. Most walerian organisms are purely filter-feeders and herbivorous, primarily feeding off of various species of floating planktons or other small organisms.

Buliae is the most common branch of organisms present on Athena. These creatures typically take the shape and appearance resembling a balloon of sorts. All creatures from sinkers to scavengers can be classified as buliae in terms of appearance.

Sailiae is the second most common branch of lifeforms of Athena classified by appearance. Sailiaes tend to resemble various creatures that use sails to fly. Sailiaes are typically limited to sinker organisms, while many floaters also can take the appearance of sailiaes.

Lifecycle Classification

Sinker organisms are the most commonly seen in the upper atmosphere of Athena and the second most common organisms classified by their lifecycle. Sinker organisms are unable to stay in a specific layer, typically tend to reproduce before falling into the planet, decomposing in a pyrolytic process, left for scavenger organisms to consume. Typically, sinker organisms can be found only in the upper clouds, being more fragile than other organisms. Sinker organisms have a same diet as floater organisms, composed of mainly floating planktons and other smaller organisms.

The floaters are most common type of organisms on Athena classified by their lifecycle, found nearly everywhere where there's life in the atmosphere of Athena. Typically, the maximum depth that floater organisms can thrive in is around a thousand kilometers, and they tend to stay in the same layer of the atmosphere by keeping their pressure level the same. An average layer for a floater species is five kilometers, and if they go below their supported range, the floaters can have their pressurized hulls destroyed by the pressure, and they fall into the deeper clouds of Athena. Floater organisms are purely filter-feeders and herbivorous, primarily feeding off of various species of floating planktons or other small organisms.

Hunter organisms are the rarest type of organisms of Athena classified by their lifecycle. They are the strongest of all the species, being able to dive down for many hundreds of kilometers and not suffering from a death by the pressure. Hunter organisms are typically the largest organisms on the planet, and most feared by the inhabitants of Athena. Their purely carnivorous diet is composed only of floater organisms, and rarely scavenger or sinker organisms if the lack of floaters ever arises.

The second rarest type of lifeforms present on Athena classified by their lifecycle, the scavengers spend most of their existence in the lower layers almost at pyrolytic height and consume the organic compounds generated by the pyrolisis of other organisms. Most scavenger organisms on Athena tend to protect themselves against the predatory hunters with their highly poisonous flesh, causing death to many individuals that have fed on them.

Interesting Species

Khizen Whale.jpg
Khizen Wraith is a species of tenctilious hunter animals found residing within the outer atmosphere. Much of the life in Athena has to survive by preying on other creatures, and the Khizen Wraith is the prime example of this lifestyle. Khizen Wraiths are a tenctilious species, possessing a high amount of tentacle-like limbs dropping down from the main body of the creature, which is essentially a large shell covering the vital organs of the creature. One of the most aggressive species in the outer atmosphere, the Khizen Wraiths tend to prey on any creature unfortunate enough to get sighted by a creature as dangerous as Khizen Wraith. As the apex predators of the upper atmosphere, the Khizen Wraiths have no natural enemies, and are at the top of their respective food chain.

Gargantua Whale is a walerian creature, with a shape with a slight resemblance to the aquatic whale organisms. Gargantua Whales are the largest floater creatures in the upper atmosphere, but the fifth largest creatures on the entire ecosystem of the planet Athena. Like most floater organisms, Gargantua Whales are primarily filter feeders, and feed off of small plankton and algae species floating around in the outer atmosphere. Gargantua Whales have four external sacks of helium and most of their body is composed of helium that it inflates and deflates to stay in the same layer of the atmosphere. This is the only way these massive beasts of almost half a kilometer in size can stay afloat in the atmosphere. Their entire body is also abnormally light, with only the most vital organs being present in their body.