Chapter 3: Planet Thexar

"She is not the largest, not the richest, not the oldest. But she is the only one who gave birth to us. And there is no other like her in all the galaxy." — From "Hymn to Thexar," classical work of the Flourishing Era

Related sections: see [Ch.01, "Cosmology"], see [Ch.02, "Star System"], see [Ch.04, "Biochemistry of Life"]

Introduction

Thexar (/ˈθɛk.sɑr/ — "earth-mother" in ancient Xha'Ruun) is the third planet of the Khar'Vex system and the only known body in the galaxy where life arose and developed. It is a world of astonishing geological diversity: from scorching equatorial deserts to polar ice caps; from the deepest ocean trenches to mountain peaks exceeding 9,500 sha.

From a planetological perspective, Thexar is distinguished by longer days, a more ancient and calm geological regime, a different atmospheric composition, and two small moons. These features shaped the unique evolutionary trajectory of local life — and, ultimately, intelligence.

Fig. 3.0. Sunset on Théxar: mountains, ocean, and both moons — Serrin and Thel.

3.1 Origin and Geological Evolution

3.1.1 Formation

Thexar formed ~6.5 billion cycles ago in the protoplanetary disk of Khar'Vex through accretion of planetesimals enriched with heavy elements (protoplanetary cloud metallicity: [Fe/H] = +0.12).

3.1.2 Internal Structure

PROFILE: Internal Structure of Thexar

Layer	Composition	State	T (°X)
Continental crust	Granite, basalt	Solid	19…534
Oceanic crust	Basalt, gabbro	Solid	45…317
Upper mantle	Peridotite (olivine+pyroxene)	Solid	534…698
Asthenosphere	Partially molten peridotite	Viscous	698…806
Lower mantle	Perovskite, ferropericlase	Solid (plastic)	806…2,057
Outer core	Fe (85%), Ni (10%), S, O (5%)	Liquid	2,057…2,710
Inner core	Fe (90%), Ni (8%), elements	Solid	2,710…2,873

3.1.3 Plate Tectonics

Thexar has active plate tectonics — the movement of lithospheric plates across the asthenosphere surface. This process is a key factor in the carbon cycle and long-term climate stability.

TABLE 3.1: Lithospheric Plates of Thexar

Plate	Type	Direction	Speed (sha/year)
Thalas (oceanic)	Oceanic	NW	3.9
Kharrak (continental)	Continental	NE	3.4
Ruval (continental)	Continental	S	5.0
Gharra (oceanic)	Oceanic	SE	3.0
Vexar (continental)	Continental	W	2.3
Northern (oceanic)	Oceanic	E	6.5
Marginal (6 small)	Mixed	Various	0.6–8.5

Plate boundary types:

• Divergent (spreading): mid-ocean ridges — 4 main (Thalass, Southern, Western, Northern)
• Convergent (colliding): subduction zones — 6 active (along the edges of continent Kharak and Rhuval)
• Transform (sliding): 4 major faults (largest — Thash Fault, ~3,900 mo long)

KEY FACT

The average speed of tectonic movements on Thexar is 2.8 sha/year. This is due to the slow cooling of the mantle (lower mass but effective insulation). Slow tectonics means longer geological cycles — in particular, the carbon cycle takes ~120 million years.

3.2 Atmosphere

3.2.1 Composition and Structure

PROFILE: Atmosphere of Thexar

Parameter	Value
Surface pressure	1 tyazh
Average surface temperature	51.6°X
Temperature range	19°X … 75°X
Average molecular mass	28.8 g/mol
Scale height	10,000 sha
Transparency (visible range)	0.72

Chemical composition (dry air, at surface):

KEY FACT

At a stellar luminosity of 0.41 L☉ and a distance of 0.63209 AU, the flux at Théxar’s orbit is about 1.026 times Earth’s solar constant. Surface temperature also depends on reflection, atmosphere, clouds and ocean heat transport.

Vertical structure of the atmosphere:

3.2.2 Sky Color

The color of Thexar's sky is one of its most striking visual features. Due to:

1. Scattering by air molecules and suspended aerosols
2. Presence of H₂S (scatters differently)
3. Orange-yellow spectrum of Khar'Vex (peak ~570 nm)

— the sky of Thexar has a characteristic golden-bronze hue, transitioning to orange near the horizon and rose-purple closer to the zenith. Sunsets are deep orange with red flashes.

3.2.3 Weather and Climate

Global atmospheric circulation is determined by:

1. Slow planetary rotation (27.3 h)
2. Active tectonics (CO₂ and SO₂ emissions)
3. Ocean currents
4. Axial tilt (14.2°)

Circulation cells:

Thexar has a 6-cell model of atmospheric circulation:

• Kharrak cell (equatorial): 0°–28° — ascending motion, abundant precipitation
• Tor cell (temperate): 28°–55° — descending motion, dry zones
• Thela cell (polar): 55°–90° — weak, cold

Due to slow rotation, the cells are wider and weaker — trade winds and monsoons are less pronounced, but winds are generally more predictable.

3.2.4 Hazardous Phenomena

3.3 Hydrosphere

3.3.1 Oceans

PROFILE: Oceans of Thexar

Parameter	Thalas (Northern)	Gharra (Southern)
Average depth	4,488 sha	3,841 sha
Maximum depth	10,268 sha (Khar-Tor Trench)	12,009 sha (Thash Deep)
Average surface T	55°X (eq.) / 43°X (pol.)	53°X (eq.) / 43°X (pol.)
Salinity	3.5%	3.3%
pH	7.9–8.1	7.8–8.2

Current system:

Thexar possesses a complex system of ocean currents:

• Tor Warm Current — transports warm water from the equatorial zone along the continent of Kharak toward the polar region
• Thash Cold Current — return current along the continent of Rhuval
• Gharra Circumpolar Current — circles the southern continent of Vexar

3.3.2 Seas

3.3.3 Rivers and Lakes

The three continents of Thexar are crossed by an extensive river network. The largest river systems:

The largest lake is the Khar Inland Sea (lake on Kharak, area 5,870 mo²), a remnant of an ancient inland sea.

3.4 Climate Zones

TABLE 3.4: Climate Zones of Thexar

Zone	Latitudes	Average T (°X)	Precipitation	Characteristic biome
Equatorial	0°–12°	60…68	2,000–4,500 mm/year	Humid jungles
Tropical	12°–28°	55…66	800–2,000 mm/year	Savannas, monsoon forests
Subtropical	28°–38°	49…58	400–900 mm/year	Mediterranean type
Temperate	38°–54°	44…55	500–1,500 mm/year	Broadleaf and mixed forests
Subpolar	54°–66°	39…49	200–600 mm/year	Coniferous forests, tundra
Polar	66°–90°	19…42	50–200 mm/year	Ice caps, desert

3.4.1 Equatorial Zone

Hot and humid belt encompassing the central regions of Thexar. Characterized by:

• Average annual temperature +63.6°X (daily range: 8–12°C → 4–7°X)
• Two rainy seasons (after equinoxes)
• Dense multi-tiered jungles with high biomass
• Red soils (iron oxides — "ferralite")
• Biodiversity: ~70% of all species on the planet

3.4.2 Polar Regions

Due to the axial tilt (14.2°), the polar regions of Thexar are covered by a permanent ice sheet.

3.5 Geography

3.5.1 Overview

3.5.2 Continent Kharak

Kharak (from the root khar- — "light," "star") is the largest continent, located in the Northern Hemisphere.

PROFILE: Kharak

Parameter	Value
Area	65.721 million km²
Population	~1.1 billion (39% of planet)
Largest city	Khar-Vexar (18.6 million)
Highest point	Mt. Verksan (9,537 sha)
Largest river	Khar-Tor (870 mo)
Climate zones	Equatorial — Polar
Natural resources	Fe, Cu, U, Pt, P, H₂S sources

Regions of Kharak:

3.5.3 Continent Rhuval

Rhuval (from the root rhuun — "great," "people") is the second largest continent, mostly in the Southern Hemisphere.

PROFILE: Rhuval

Parameter	Value
Area	42.249 million km²
Population	~0.9 billion (32% of planet)
Largest city	Ven-Khal (12.4 million)
Highest point	Mt. Moraat (7,915 sha)
Largest river	Thash-Ven (776 mo)
Climate	Tropical — Subpolar
Natural resources	Au, Ag, Zn, oil, gas

Regions of Rhuval:

• Raal Plateau — highland plateau, mining center
• Thash-Ven Valley — densely populated agricultural area
• Irkhen Coast — resort zone, ancient ports

3.5.4 Continent Vexar

Vexar (from the root vex- — "to give," "to create") is the smallest of the three continents, the most isolated.

PROFILE: Vexar

Parameter	Value
Area	37.555 million km²
Population	~0.5 billion (18% of planet)
Largest city	Shan-En (7.8 million)
Highest point	Mt. Sharrus (7,451 sha)
Largest river	Sharrus (638 mo)
Climate	Subtropical — Subpolar
Natural resources	Ti, Mn, Cr, Co, rare earths

3.5.5 Island Territories

3.6 Magnetosphere and Radiation Belt

3.6.1 Magnetic Field

Thexar possesses an active magnetic field, generated by the dynamo effect in the liquid outer core.

3.6.2 Radiation Belt

Thexar has two radiation belts:

• Inner belt: altitude 1,463–5,488 sha, consists of high-energy protons
• Outer belt: altitude 9,756–21,951 sha, consists of electrons

KEY FACT

The magnetosphere is one of the reasons the Xha'Ruun developed increased radiation resistance (see [Ch.05, "Physiology"]). Evolution "got used" to a somewhat higher level of cosmic radiation penetrating through the weakened magnetosphere.

3.7 Biomes and Key Ecosystems

3.7.1 Biome Map

3.7.2 Unique Ecosystems

Deep-sea hydrothermal vents — in the Gharra Ocean, at depths of 4,268–9,146 sha, ecosystems based on H₂S chemosynthesis have formed around 6 hydrothermal vent fields (see [Ch.04, "Biochemistry"]). These "oases" of life contain endemic species found nowhere else on the planet.

Cave ecosystems — in the limestone massifs of Kharak and Vexar, large subterranean ecosystems have been discovered (total area ~9,917 mo²), isolated from the surface for millions of years. Many species are blind, depigmented.

RELATION

The biodiversity of Thexar and key evolutionary adaptations are described in detail in see [Ch.04, "Biochemistry"] and see [Ch.05, "Xha'Ruun Species"].

3.8 Natural Resources

TABLE 3.8: Mineral Resources of Thexar

Resource	Reserves	Main region	Use
Iron	1.27 × 10¹¹ ru	Kharak (Khar-Tor Range)	Industry
Copper	1.94 × 10⁹ ru	Rhuval (Raal Plateau)	Electrical, alloys
Uranium	5.09 × 10⁶ ru	Kharak (Shan Desert)	Energy (historically)
Thorium	2.48 × 10⁷ ru	Vexar (coast)	Thermonuclear energy
Platinum group	1.70 × 10⁵ ru	Kharak (Khar-Tor)	Catalysts, electronics
Rare earths	5.58 × 10⁷ ru	Vexar	Electronics, superconductors
Gold	9.09 × 10⁴ ru	Rhuval (Thash-Ven)	Electronics, jewelry
Phosphates	5.15 × 10¹⁰ ru	Kharak (sedimentary)	Fertilizers

Energy resources:

3.9 Natural Threats

3.9.1 Earthquakes

Due to active tectonics, Thexar experiences ~15,000 earthquakes of magnitude > 2.0 annually.

3.9.2 Volcanism

Thexar has ~180 active volcanoes, of which ~30 are supervolcanoes (capable of VEI-8 eruptions).

3.9.3 Impact Events

Thexar is subjected to asteroid and comet impacts with a frequency of ~1 major event (crater >10 km) every 500,000 years. Planetary defense system — see [Ch.09, "Planetary Defense"].

3.10 Thexar in Culture

QUOTE

"Three continents — three characters. Kharak — old, wealthy, wise. Rhuval — young, passionate, warlike. Vexar — detached, mysterious, proud. So say the geographers. But the inhabitants of each are certain that their continent is the best. And each is right in their own way."

— "Geography for Travelers," popular edition, +2,500 y.E.U.

In Xha'Ruun culture, Thexar is perceived as a living entity — the "Great Mother." The oceans are associated with the circulatory system, the mountains with the skeleton, the winds with breath. This metaphor is deeply rooted in the language: the verb "to breathe" (shal-ven) and "to blow (of wind)" (shal-thar) share a common root.

RELATION

The attitude toward the planet as a living being is not only a poetic metaphor but also the foundation of Xha'Ruun ecological ethics (see [Ch.08, "Culture"]), as well as an element of religious worldview (see [Ch.10, "Mythology"]).

Chapter 3 Summary

Key Takeaways

1. Thexar is a geologically active planet with a fully differentiated core, plate tectonics (7 main plates), and volcanism
2. Atmosphere is rich in CO₂ (0.8%) — this is compensation for low insolation, not a greenhouse catastrophe
3. The sky is golden-orange due to atmospheric composition and stellar spectrum
4. Hydrosphere: 2 oceans, 5 seas, 67% of surface covered by water
5. 3 continents: Kharak (65.721 million km²), Rhuval (42.249 million km²), Vexar (37.555 million km²)
6. Magnetosphere is moderate (42 µT), atmosphere compensates for its weakening
7. Rich mineral resources — especially Fe, Cu, Th, Pt on Kharak
8. Energy: 62% — thermonuclear, solar and hydroelectric power

Links to Other Chapters

• see [Ch.02, "Star System"] — position of Thexar in the system and habitable zone
• see [Ch.04, "Biochemistry"] — how Thexar's geochemistry shaped the biochemistry of life
• see [Ch.05, "Xha'Ruun Species"] — evolutionary adaptations to the environment
• see [Ch.09, "Technologies"] — use of geothermal energy and resources
• see [APP:physical-ref] — complete planet profile