{
    "GJ0b": {
        "_comment": "Mercury — barren rock, tidally locked, extreme temps",
        "orbit": { "axial_tilt_deg": 0.034 },
        "terrain": { "land_fraction": 1.0, "tectonics": "none" },
        "environment": { "geothermal_flux": "low", "substrate": "silicate" }
    },
    "GJ0c": {
        "_comment": "Venus — thick sulfuric acid clouds hide the surface completely",
        "orbit": { "axial_tilt_deg": 177.4 },
        "terrain": { "land_fraction": 1.0, "tectonics": "active" },
        "physical": { "atmosphere_color": [0.92, 0.85, 0.55] },
        "environment": { "geothermal_flux": "high", "substrate": "silicate" },
        "clouds": { "enabled": true, "coverage_base": 0.95 }
    },
    "GJ0d": {
        "_comment": "Earth — use real-world data pipeline",
        "orbit": { "axial_tilt_deg": 23.44 },
        "terrain": { "land_fraction": 0.29, "polar_ice_lat": 0.85, "tectonics": "active" },
        "environment": { "hydrosphere": "ocean", "geothermal_flux": "low" },
        "clouds": { "enabled": true, "coverage_base": 0.5 }
    },
    "GJ0d-1": {
        "_comment": "Luna — barren, tidally locked",
        "orbit": { "axial_tilt_deg": 6.68 },
        "terrain": { "land_fraction": 1.0, "tectonics": "none" },
        "environment": { "geothermal_flux": "low", "substrate": "silicate" }
    },
    "GJ0e": {
        "_comment": "Mars — thin atmo, partially terraformed in lore (800 years)",
        "orbit": { "axial_tilt_deg": 25.19 },
        "terrain": { "land_fraction": 0.98, "polar_ice_lat": 0.65, "tectonics": "none" },
        "environment": { "hydrosphere": "ice", "geothermal_flux": "low", "substrate": "silicate" }
    },
    "GJ0f": {
        "_comment": "Jupiter — gas giant, Great Red Spot",
        "gas_giant": {
            "band_palette": "jovian",
            "storm_count": 2,
            "storm_max_size": 0.12
        },
        "rings": false
    },
    "GJ0f-1": {
        "_comment": "Io — volcanic moon of Jupiter, tidal heating",
        "terrain": { "land_fraction": 1.0, "tectonics": "extreme" },
        "environment": { "geothermal_flux": "high", "substrate": "silicate", "chemosynthetic": false }
    },
    "GJ0f-2": {
        "_comment": "Europa — ice moon, subsurface ocean",
        "terrain": { "land_fraction": 1.0, "tectonics": "low" },
        "environment": { "geothermal_flux": "low", "substrate": "ice" }
    },
    "GJ0f-3": {
        "_comment": "Ganymede — largest moon, ice/rock dichotomy",
        "terrain": { "land_fraction": 1.0, "tectonics": "none" },
        "environment": { "geothermal_flux": "low", "substrate": "ice" }
    },
    "GJ0f-4": {
        "_comment": "Callisto — heavily cratered ice moon",
        "terrain": { "land_fraction": 1.0, "tectonics": "none" },
        "environment": { "geothermal_flux": "low", "substrate": "ice" }
    },
    "GJ0g": {
        "_comment": "Saturn — gas giant with prominent ring system",
        "gas_giant": {
            "band_palette": "saturnian",
            "storm_count": 1,
            "storm_max_size": 0.06
        },
        "rings": {
            "enabled": true,
            "inner_radius_factor": 1.12,
            "outer_radius_factor": 2.65,
            "opacity_base": 0.68,
            "ring_color": [0.88, 0.78, 0.55]
        }
    },
    "GJ0g-1": {
        "_comment": "Titan — dense atmosphere, methane cycle",
        "terrain": { "land_fraction": 0.60, "tectonics": "low" },
        "environment": { "hydrosphere": "rivers", "geothermal_flux": "low", "substrate": "ice" }
    },
    "GJ0g-2": {
        "_comment": "Enceladus — small ice moon, geysers",
        "terrain": { "land_fraction": 1.0, "tectonics": "low" },
        "environment": { "geothermal_flux": "moderate", "substrate": "ice" }
    },
    "GJ0h": {
        "_comment": "Uranus — ice giant, extreme axial tilt",
        "orbit": { "axial_tilt_deg": 97.8 },
        "gas_giant": {
            "band_palette": "icy",
            "storm_count": 1,
            "storm_max_size": 0.04
        },
        "rings": false
    },
    "GJ0i": {
        "_comment": "Neptune — ice giant, active storms",
        "gas_giant": {
            "band_palette": "neptunian",
            "storm_count": 3,
            "storm_max_size": 0.08
        },
        "rings": false
    }
}