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Habitability
12/ 100
Uninhabitable

KZO-88+765543 b

0

Carbon World

Magnetic FieldModerate Activity
Why is this a Carbon World?Your planet's carbon (52.3%) outweighs its oxygen (0.0%), so the mineralogy flips from silicate rock to carbide - a graphite crust over a diamond mantle.
Carbon worlds form in carbon-rich disks where there isn't enough oxygen to bind it all into silicates. Instead carbon condenses directly into graphite, carbides, and - under pressure at depth - diamond. They form water-poor, so no life takes hold.
Classification Criteria:
✓ Carbon: 52.3% (>=20% required)✓ Carbon exceeds Oxygen: 52.3% > 0.0%✓ Mass: 1.8x Earth (<=8x hycean ceiling)
Habitability ScoreUninhabitable
12
Contributing Factors
water0
No water - the recipe has no hydrogen and oxygen to form it
geology90
Active geology recycles nutrients and drives carbon cycle
rotation100
Optimal rotation period - balanced day/night cycle, moderate weather, and good heat distribution
Organic Chemistry50
Carbon and hydrogen present - organic chemistry possible
atmosphere40
Atmosphere present but composition not ideal for life
temperature40
Extreme temperature - very difficult for life
magnetic Field100
Magnetic field provides radiation protection

Physical Properties

Mass
1.80x Earth (1.07e+25 kg)
Radius
1.22x Earth (7,750 km)
This planet: 1.22× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.22x Earth (11.9 m/s²)
Surface Temperature
393 K (120 °C / 248 °F)
Rotation Period
20.0 hours/day (faster than Earth)
This planet: 20 h/dayEarth: 24 h/day

Orbital Environment

Star Type
M-type (Red Dwarf)
Distance from Star
0.10 AU (15 million km)
Orbital Period
21 days

Atmosphere

Carbon monoxide and methane haze over a graphite surface

Elemental Composition

C - Carbon
52.3%
Fe - Iron
17.4%
Si - Silicon
17.4%

Surface Characteristics

Graphite plains and carbide ridges over a diamond mantle - a glittering coal-black world

Closest Real Exoplanet

TOI-4336 A c95% similar
Orbiting TOI-4336 A
YoursTOI-4336 A c
Mass1.80 × Earth1.55 × Earth
Radius1.32 × Earth1.25 × Earth
Density (composition)4.36 g/cm³4.37 g/cm³
Temperature393.2 K400.0 K
Starlight received4.00 × Earth4.24 × Earth
Star temperature3,050 K3,307 K
Discovered 2026 via transit · 73 light-years awaySource: NASA Exoplanet Archive
Surface views from three worlds: rocky ground under a ringed sky, a cloud deck, and a lit desert

New: Stand on Your World 🏔️

Every planet you build can now be seen from the ground. The terrain, the color of the sky, the weather and what hangs overhead are all read from the same numbers that shape the globe — so a thin-aired world gives you sunlit rock under a near-black sky crowded with stars, a runaway greenhouse seals you under an unbroken sulfur lid, and a gas giant leaves you in the cloud tops with nothing solid beneath you at all. If one of your moons wandered inside the Roche limit, what is left of it arcs overhead as rings.

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