Introduction: Origins and Environmental Catalysts#

Kethra Almanac • Approved 19 September 2026 • drafted 18 September 2026

Status: approved. Briana approved the whole almanac on 19 September 2026 (the Almanac Approval Decision). Where this file calls something a proposal, read it as approved, except the open points that decision lists.

Status before approval: §0.1 restates canon. Everything else is a proposal built on the spine.

0.1 Cosmic Context & Planetary Metrics#

Canon except where marked.

The Aion system. Kethra orbits Theia (frontier name: Sól), a yellow-white G-class star. Theia is about 5.5 billion years old and about 10% brighter than our Sun is today. Far outside Kethra's orbit, the red giant Hyperion (frontier name: Surtr) swings between about 150 and 450 AU, completing one orbit in about 3,500 Earth years (about 3,204 Kethran years). The system also contains:

• a gas giant at about 5 AU, named Kronos in the capital and Ymir on the frontier (these names are a proposal);
• the Cinderbelt, a rubble belt at about 50 AU, at the edge of Theia's system.

Where Hyperion is now (proposal, AL 2314). Hyperion is about 195 AU away and closing. It adds about 0.76% to the heat Kethra receives, and red nights are about 250 lux: roughly the light of a dim room, coloured deep red-orange. It will reach its closest point around AL 2539. Over a single human lifetime the red nights brighten by about a fifth. That is enough for any grandparent to notice, and enough to argue about.

0.2 The Cradle: Original Habitats & Geography#

The ground itself#

Kethra is geologically alive. Plate tectonics recycles its crust, which keeps its carbon cycle and climate stable over long ages, as on Earth.

The Stair#

Every warm era raises the seas and every cool one lowers them, while the land along Calathe's southern coast slowly rises. Over hundreds of thousands of years this has left a staircase of raised beaches: bands of old shoreline stepping up the coasts. These are called the Stair. The youngest step, from the last hot era about 3,000 Earth years ago, stands about 12 m above today's sea. The oldest steps in the Thess estuary stand about 140 m up, and the slopes between steps are steep. The steps are flat, well drained and easy to build on. The Founders built on them, and so has almost everyone since. Aletheia, the capital, rises in terraces up the Thess estuary Stair.

The working behind these dates: Hyperion's last closest approach was around AL −665, about 726 Earth years before Landfall. Add the roughly 2,528 Earth years since Landfall and the peak was about 3,250 Earth years ago. Seas lag behind temperature by centuries, so the seas stood highest a few centuries after the peak, roughly 2,800 to 3,100 Earth years ago. They were still falling when the Founders arrived.

Native biomes#

Native plants are dark: deep purple, bronze and near-black. Their pigments absorb both Theia's yellow-white light and Hyperion's red. Native biomes were named in Landspeech by the Founders:

The first habitats#

Why the Founders chose Landfall. They picked the south coast of Calathe at the mouth of the Thess, for four reasons:

• It is temperate.
• The river gives fresh water.
• The Stair offered flat, freshly exposed ground where native life was thin and Earth soil cultures could take hold quickly.
• The deep tidal estuary made a harbour.

The Seven Terraces. The first settlement was built on seven steps of the Stair above the estuary. It is still called the Seven Terraces, and it is now a quarter of the town of Landfall.

Spreading out. From Landfall, settlement spread up the Thess valley and along the Calathe coast. It moved only as fast as native ground could be seeded with Earth life (see 0.4). This is why the old heartland is a long chain of river-valley farmland, with Wild on either side.

0.3 Climatological Drivers#

What makes Kethra's weather different from Earth's#

1. Slower spin. A 26-hour day gives slightly weaker spin effects on the winds than Earth's. As a result:
   • the tropical wind belts are wider;
   • the dry subtropical deserts sit a little further from the equator, at about 33–38° latitude instead of Earth's 30°;
   • tropical storms grow larger and move more slowly.
2. Stronger tilt. At 27°, summers are hotter and winters colder than at the same latitude on Earth. Polar nights are longer.
3. Richer air. With 23% oxygen, fires ignite more easily and burn hotter.
4. Two moons. Tides are strong and complex, and shallow coasts mix constantly with the open ocean.
5. Hyperion. It gives light through the red-night season and a slowly rising share of heat over the centuries.

Severe weather#

Ocean and air currents#

• The Girdle Current runs westward along the equator. Every Rovessa route is built around it.
• The Warm Reach carries warm, wet tropical water along the southern and eastern coasts of Calathe. Rain-bearing winds come off it all year. This is why the Thess coast, where Aletheia stands at 34° N, is green and humid rather than part of the dry subtropical belt. The deserts at that latitude lie in the continental interiors and on the west-facing coasts.
• The Southern Cold flows up from the Southern Ice along western Eldvang. It keeps that coast foggy, dry and rich in native sea life.
• Winds follow bands like Earth's, but wider: easterlies in the tropics, westerlies at mid-latitudes, and polar easterlies near the poles.

How the seasons turn#

Why the red nights matter to farming#

Native plants photosynthesise in Hyperion's deep red light. Earth crops barely can. During every red-night season the native Wild keeps growing through the night, while Earth fields merely rest, so the Wild presses in on the farmland. As Hyperion brightens, the Wild's advantage grows. This is the practical engine of Kethra's environmental politics:

• The farmers of the capital call it "the Creep".
• The Living Worlds Movement calls it the planet reasserting itself.

Long cycles#

Hyperion and the gas giant together stretch and relax Kethra's orbit over tens of thousands of years. Combined with the slow wobble of Kethra's axis, this produces ice ages and warm periods. Ilyr scholars have reconstructed several of these cycles from sediment cores. The Cantorate's position is that they are of no religious concern.

0.4 Natural Resources & Abundance Variances#

The chemistry that shapes everything#

Native life on Kethra is built from carbon, water and proteins, like Earth life, but it evolved separately:

• Its sugars are mirror images of Earth's.
• It uses three amino acids that Earth life never uses.

The consequence is that most native food is indigestible to humans, and some is poisonous. Humans live on Earth-descended crops and livestock, grown in seeded ground called gardenland. Processed native foods can be eaten only because of the Gift, the Founder-engineered gut flora described in Chapter I. Even then, they have to be leached and cooked first.

Seeding the ground#

Native soil does not support Earth crops until it has been converted. Farmers do this with Earth soil cultures: bacteria, fungi and worms descended from the Founders' soil banks. Converting a field is known as the Seeding. It takes about 30 years to reach full yield. As a result:

• Farmland is precious and inherited.
• Taking another state's gardenland is the oldest reason for war.
• Converting new land is a multi-generation investment. The capital's banks lend against it.

Minerals and materials#

Water#

• Calathe: abundant rivers, fed by the Corran snows and the northern longstorms.
• Oreth: a wet western coast and a dry interior.
• The Line Isles: heavy rainfall, and cisterns in every town.
• Eldvang: well watered in the eastern highlands and along the rift; arid across the interior plateau. Water rights are the frontier's second great source of disputes, after the charters.

Energy reserves in brief#

Tidal power is Kethra's great renewable resource, and the Thess estuary is the best site on the planet. Fusion fuel comes from Kronos/Ymir. Thorium is plentiful. Solar power works, but gives less than it would on Earth at the same latitudes because of the long winter nights.

0.5 Flora and Fauna Trajectories#

Two kingdoms of life#

Naturalists divide all life on Kethra into two separate trees:

Native animals#

Most native land animals have six limbs. Some walk on all six; others walk on four and handle things with two. Native animals find humans as inedible as humans find them. Native predators therefore attack people to defend territory, or by mistake, not to eat them. Most learn to avoid humans. The exceptions are the ones people fear.

Domesticated species#

Earthkin that went wild#

• Rats arrived with the Founders against every precaution. They are the most successful Earth animal outside the gardenland, living on human stores and waste.
• Feral goats strip seeded ground at the edges of the Wild.
• Earth grasses invade the margins of the Wild. The Living Worlds Movement treats this as a harm to the native Wild.

Where the two kinds of life meet: the Hedge#

The boundary between gardenland and Wild is called the Hedge, and it is a live front. Earth weeds and feral animals push outward from the fields. Native growth, including blackthatch, a fast native creeper, pushes inward during every red-night season. Hedge work is its own trade: clearing, burning and re-seeding the boundary.

Where things are heading#

The Living Worlds Movement argues that the coming hot era is the native Wild's season, and that humanity must set limits on the Seeding before the planet sets them instead. The Cantorate teaches that the Father's Return will be a time of plenty. Farmers watch the Hedge.

Guidance for AI actors#

• Every scene has a red-night status. In the northern winter nights are red-lit; in the northern summer they are black. In the south it is the reverse. Characters plan around it.
• Food is never casual. Everyone knows which foods are Earthkin and which are processed native. Offering someone the wrong food is an insult, or a danger.
• Tides. People living on the coast know the moons' positions the way people on Earth know the weather.
• What a person knows about native animals depends on where they live. A capital clerk has never seen a tidehound. A frontier child can imitate its call.

Prepared by Claude.