Uninhabitable volcanic world far from its sun; five moons and a composition heavy in uranium contribute to its internal heat even as most of the surface is extremely cold.
No life — too cold for liquid waterExtreme Activity
Why is this a Volcanic World?Runaway tidal heating from its moons drives volcanism across a cold crust - the planet is kneaded like Io.
Resonant, close-in moons pump orbital eccentricity, and the resulting tidal flexing dissipates enormous heat in the interior. Only a fraction of the surface is molten at once, so the ground between the vents stays as cold as the orbit allows - Io's own equilibrium temperature is about 110 K.
Classification Criteria:
✓ Close-in moons in a resonant configuration✓ Tidal heat flux beyond the runaway threshold- The orbit is not what melted it: 3.70 AU, 145K equilibrium
Habitability ScoreUninhabitable
0
Contributing Factors
water20
Very dry - minimal water
geology40
Extreme volcanic activity may be hazardous
rotation10
Near tidally locked - one hemisphere perpetually scorched, other frozen, narrow habitable twilight zone only
Organic Chemistry100
All CHNOPS elements present - building blocks of life
atmosphere16
Atmosphere present but composition not ideal for life (partially stripped by slow rotation)
temperature0
Very cold - water frozen, challenging for life (large moon stabilizes the axial tilt - steady seasons) (runaway tidal heating keeps the surface molten regardless of orbit)
magnetic Field35
No magnetic field - vulnerable to solar radiation (a large close moon may help stir the core dynamo (speculative))
Physical Properties
Mass
0.30x Earth (1.79e+24 kg)
Radius
0.67x Earth (4,265 km)
Surface Gravity
0.67x Earth (6.6 m/s²)
Surface Temperature
145 K (-129 °C / -200 °F)
Rotation Period
12.0 hours/day (faster than Earth)
Orbital Environment
Star Type
G-type (Yellow (Sun-like))
Distance from Star
3.70 AU (554 million km)
Orbital Period
7.12 years
Atmosphere
Volcanic outgassing - sulfur compounds and vaporized rock
Elemental Composition
U - Uranium
17.7%
O - Oxygen
13.6%
Si - Silicon
13.6%
Surface Characteristics
Runaway tidal heating drives volcanism across a cold crust - lava lakes and sulfur plains between frozen plains
Outside the synchronous orbit: slowly receding, like Luna (~cm per year).
Tidal braking locked the planet to its moon: one face forever moonward.
Moon 2merged1.0% - 6.2 radii
Merged with an adjacent moon: too close for both to hold a stable orbit.
Moon 3receding0.040% - 45.9 radii
Outside the synchronous orbit: slowly receding, like Luna (~cm per year).
Moon 4merged0.040% - 48.0 radii
Merged with an adjacent moon: too close for both to hold a stable orbit.
Moon 5stable0.010% - 92.3 radii
Small and distant: a quiet, stable companion.
+5 temperature: large moon stabilizes the axial tilt - steady seasons-85 temperature: runaway tidal heating keeps the surface molten regardless of orbit+5 magneticField: a large close moon may help stir the core dynamo (speculative)