100th Millennium Wiki


Eiar is the 8th and last planet orbiting Castro, in the Castro-Lux system. It is a hydrocarbonia warmed up by tidal heating from its moon, Ver. What is interesting is that Ver is actually nearly as massive as Eiar. Ver is 99.5% the mass of Eiar, making the two a binary planet. They orbit Castro every 6.9 years.


Eiar is far too cold for anything to live on the surface without support, but it has a strangely large amount of radioactive material in its core, which allows a safer temperature to be reached in the deep caves. Life always finds a way, and eventually the Areial species evolved. The Areial have since constructed vast cities in the deep pockets beneath the surface, and they were recently contacted by the United Nations of the Florathel Galaxy, allowing them to expand outwards, colonizing the entire Castro-Lux System.


Roughly 1.4 billion years ago, Eiar formed from a series of planetesimals colliding around the red dwarf Castro. around 100 million years later, it was forced inward by Lux's rapid mass gain to the region of prehistoric Ver. At this point, Ver impacted Eiar, forming a synestia at the location, and this recoalesced into two new planets, again named Eiar and Ver.

Around 1 billion years ago, Eiar has cooled enough to form globe-spanning oceans of liquid water, but this rapidly froze as they were maintained by only internal heat. Hydrocarbons and other molecules like ammonia rain down, replacing the frozen water oceans. At this point, Ver looks like it does today.

The Areial species begins to evolve at just over 500,000 years ago, and reach their present biological state 140 thousand years ago. At this point, they slowly develop technology, arriving at their industrial revolution around 0 CE. However, because they live in the large interlinked ice caves beneath the surface, it took a very long time for them to break through and make contact with the wider universe, only doing so when a Garrean survey probe broke through the ice in 56452 CE.

After this, the Areial rapidly expanded, conquering the entire Treana Nebula, and forming the Areial Union with its capital at Eiar itself. Recently, the Amgorac Dynasty broke away, although this did not really affect the core regions.


Artist's depiction of early Eiar

Due to being in a binary planet, Eiar has some very interesting geological features.

Claw marks

Sometimes looking at Eiar, you can see what looks like claw markings. These are actually pools of moving methane centered on elongated valleys caused by tidal squeezing from Ver, and they are slightly eroded, making the pools harder and harder to drain out. They are still like this to this day.

Patchy areas

There are many patchy areas around the planet. It is not exactly known why these exist, but it is thought to have been the interaction between the ground and the exclusively-hydrogen atmosphere.

Patchy Areas

Claw marks

Binary Companion

Eiar's binary companion is in the form of the planet Ver. Ver is an ecumenopolis world that is actually more populous than Eiar itself due to less of a desire to preserve its natural form. Ver was fomerly a desolate world, forming from the collision between Eiar and an ancient planet.