{
  "family": "solar-system",
  "name": "Solar System Worlds",
  "generatedAt": "2026-10-14",
  "count": 5,
  "objects": [
    {
      "id": "sol:jupiter",
      "slug": "jupiter",
      "canonicalName": "Jupiter",
      "aliases": [
        "Jove",
        "Sol V"
      ],
      "constellation": "Ecliptic (Zodiac)",
      "path": "/objects/solar-system/jupiter/",
      "coordinates": {
        "raHours": 6,
        "raSexagesimal": "06h 00m 00.00s",
        "decDegrees": 23,
        "decSexagesimal": "+23° 00′ 00.0″",
        "epoch": "J2000.0",
        "sourceId": "src:jpl-horizons"
      },
      "classification": {
        "primaryClass": "Hydrogen-helium gas giant planet (most massive planet in the Solar System)"
      },
      "measurements": [
        {
          "id": "sol:jupiter:vmag",
          "entityId": "sol:jupiter",
          "property": "apparent_magnitude_v",
          "label": "Maximum opposition visual magnitude (V)",
          "value": -2.94,
          "unit": "mag",
          "uncertainty": {
            "kind": "range",
            "min": -2.94,
            "max": -1.66
          },
          "method": "JPL planetary ephemeris photometry (varies from −2.94 at perihelic opposition to −1.66 at conjunction)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:jupiter:sma",
          "entityId": "sol:jupiter",
          "property": "semi_major_axis_au",
          "label": "Orbital semi-major axis",
          "value": 5.2038,
          "unit": "AU",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.0001
          },
          "method": "JPL DE441 planetary ephemeris (e = 0.0489)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:jupiter:period",
          "entityId": "sol:jupiter",
          "property": "orbital_period_days",
          "label": "Sidereal orbital period",
          "value": 4332.59,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.01
          },
          "method": "JPL DE441 ephemeris (11.862 Julian years; synodic opposition period = 398.88 d)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:jupiter:mass",
          "entityId": "sol:jupiter",
          "property": "mass_earth",
          "label": "Planetary mass",
          "value": 317.828,
          "unit": "M⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.001
          },
          "method": "Juno/Galileo spacecraft radio-Doppler tracking (1.89813 × 10^27 kg)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:jupiter:radius",
          "entityId": "sol:jupiter",
          "property": "radius_earth",
          "label": "Equatorial 1-bar radius",
          "value": 11.209,
          "unit": "R⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.001
          },
          "method": "Radio occultation & imaging (71,492 km equatorial vs 66,854 km polar)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:jupiter:ang-size",
          "entityId": "sol:jupiter",
          "property": "angular_size_arcmin",
          "label": "Peak opposition equatorial diameter",
          "value": 0.835,
          "unit": "arcmin",
          "uncertainty": {
            "kind": "range",
            "min": 0.497,
            "max": 0.835
          },
          "method": "Spans 50.1 arcseconds at perihelic opposition down to 29.8 arcseconds at conjunction",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:jpl-horizons"
      ]
    },
    {
      "id": "sol:saturn",
      "slug": "saturn",
      "canonicalName": "Saturn",
      "aliases": [
        "Sol VI"
      ],
      "constellation": "Ecliptic (Zodiac)",
      "path": "/objects/solar-system/saturn/",
      "coordinates": {
        "raHours": 23.5,
        "raSexagesimal": "23h 30m 00.00s",
        "decDegrees": -5,
        "decSexagesimal": "-05° 00′ 00.0″",
        "epoch": "J2000.0",
        "sourceId": "src:jpl-horizons"
      },
      "classification": {
        "primaryClass": "Obate hydrogen-helium gas giant with extensive icy ring system"
      },
      "measurements": [
        {
          "id": "sol:saturn:vmag",
          "entityId": "sol:saturn",
          "property": "apparent_magnitude_v",
          "label": "Opposition visual magnitude (V)",
          "value": 0.4,
          "unit": "mag",
          "uncertainty": {
            "kind": "range",
            "min": -0.55,
            "max": 1.17
          },
          "method": "JPL ephemeris photometry (varies strongly with ring tilt angle from −0.55 wide-open to +0.8 edge-on)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:saturn:sma",
          "entityId": "sol:saturn",
          "property": "semi_major_axis_au",
          "label": "Orbital semi-major axis",
          "value": 9.5826,
          "unit": "AU",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.0002
          },
          "method": "JPL DE441 planetary ephemeris (e = 0.0565)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:saturn:period",
          "entityId": "sol:saturn",
          "property": "orbital_period_days",
          "label": "Sidereal orbital period",
          "value": 10759.22,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.05
          },
          "method": "JPL DE441 ephemeris (29.457 Julian years; synodic period = 378.09 d)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:saturn:mass",
          "entityId": "sol:saturn",
          "property": "mass_earth",
          "label": "Planetary mass",
          "value": 95.159,
          "unit": "M⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.001
          },
          "method": "Cassini spacecraft radio-Doppler tracking (5.6834 × 10^26 kg)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:saturn:radius",
          "entityId": "sol:saturn",
          "property": "radius_earth",
          "label": "Equatorial 1-bar radius",
          "value": 9.449,
          "unit": "R⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.001
          },
          "method": "Cassini radio occultations (60,268 km equatorial vs 54,364 km polar)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:jpl-horizons"
      ]
    },
    {
      "id": "sol:mars",
      "slug": "mars",
      "canonicalName": "Mars",
      "aliases": [
        "The Red Planet",
        "Sol IV"
      ],
      "constellation": "Ecliptic (Zodiac)",
      "path": "/objects/solar-system/mars/",
      "coordinates": {
        "raHours": 4.5,
        "raSexagesimal": "04h 30m 00.00s",
        "decDegrees": 22,
        "decSexagesimal": "+22° 00′ 00.0″",
        "epoch": "J2000.0",
        "sourceId": "src:jpl-horizons"
      },
      "classification": {
        "primaryClass": "Rocky terrestrial planet with thin CO2 atmosphere and seasonal polar caps"
      },
      "measurements": [
        {
          "id": "sol:mars:vmag",
          "entityId": "sol:mars",
          "property": "apparent_magnitude_v",
          "label": "Peak perihelic opposition magnitude (V)",
          "value": -2.94,
          "unit": "mag",
          "uncertainty": {
            "kind": "range",
            "min": -2.94,
            "max": 1.86
          },
          "method": "JPL ephemeris photometry (swings by 4.8 magnitudes between perihelic opposition and aphelic conjunction)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:mars:sma",
          "entityId": "sol:mars",
          "property": "semi_major_axis_au",
          "label": "Orbital semi-major axis",
          "value": 1.52368,
          "unit": "AU",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.00001
          },
          "method": "JPL DE441 planetary ephemeris (eccentricity e = 0.0934)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:mars:period",
          "entityId": "sol:mars",
          "property": "orbital_period_days",
          "label": "Sidereal orbital period",
          "value": 686.98,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.01
          },
          "method": "JPL DE441 ephemeris (1.8808 Julian years; synodic opposition period = 779.94 d)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:mars:mass",
          "entityId": "sol:mars",
          "property": "mass_earth",
          "label": "Planetary mass",
          "value": 0.10745,
          "unit": "M⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.00001
          },
          "method": "Spacecraft tracking (6.4171 × 10^23 kg)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:mars:radius",
          "entityId": "sol:mars",
          "property": "radius_earth",
          "label": "Mean volumetric radius",
          "value": 0.532,
          "unit": "R⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.001
          },
          "method": "MOLA laser altimetry (3,389.5 km)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:mars:ang-size",
          "entityId": "sol:mars",
          "property": "angular_size_arcmin",
          "label": "Apparent diameter at opposition",
          "value": 0.418,
          "unit": "arcmin",
          "uncertainty": {
            "kind": "range",
            "min": 0.058,
            "max": 0.418
          },
          "method": "Ranges from 3.5″ at conjunction to 13.8″ at aphelic opposition and 25.1″ at perihelic opposition",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:jpl-horizons"
      ]
    },
    {
      "id": "sol:titan",
      "slug": "titan",
      "canonicalName": "Titan (Saturn VI)",
      "aliases": [
        "Saturn VI"
      ],
      "constellation": "Saturn System (Ecliptic)",
      "path": "/objects/solar-system/titan/",
      "coordinates": {
        "raHours": 23.505,
        "raSexagesimal": "23h 30m 18.00s",
        "decDegrees": -5,
        "decSexagesimal": "-05° 00′ 00.0″",
        "epoch": "J2000.0",
        "sourceId": "src:jpl-horizons"
      },
      "classification": {
        "primaryClass": "Planetary-scale icy moon with dense nitrogen-methane atmosphere and surface lakes"
      },
      "measurements": [
        {
          "id": "sol:titan:vmag",
          "entityId": "sol:titan",
          "property": "apparent_magnitude_v",
          "label": "Opposition visual magnitude (V)",
          "value": 8.4,
          "unit": "mag",
          "uncertainty": {
            "kind": "range",
            "min": 8.2,
            "max": 9
          },
          "method": "JPL planetary satellite ephemeris photometry",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:titan:period",
          "entityId": "sol:titan",
          "property": "orbital_period_days",
          "label": "Orbital period around Saturn",
          "value": 15.94542,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.00001
          },
          "method": "Cassini & ground-based astrometric ephemeris (semi-major axis = 1,221,870 km / 20.27 R_Saturn)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:titan:radius",
          "entityId": "sol:titan",
          "property": "radius_earth",
          "label": "Solid-surface radius",
          "value": 0.4043,
          "unit": "R⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.0002
          },
          "method": "Cassini radar altimetry & radio occultation (2,574.7 km — larger than Mercury!)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:titan:mass",
          "entityId": "sol:titan",
          "property": "mass_earth",
          "label": "Satellite mass",
          "value": 0.0225,
          "unit": "M⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.0001
          },
          "method": "Cassini flyby radio-Doppler tracking (1.3452 × 10^23 kg, 1.83 × Moon)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:titan:teq",
          "entityId": "sol:titan",
          "property": "effective_temperature_k",
          "label": "Surface temperature",
          "value": 93.7,
          "unit": "K",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.6
          },
          "method": "ESA Huygens lander in-situ surface measurement (−179.5 °C at 1.45 bar)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:jpl-horizons"
      ]
    },
    {
      "id": "sol:europa",
      "slug": "europa",
      "canonicalName": "Europa (Jupiter II)",
      "aliases": [
        "Jupiter II"
      ],
      "constellation": "Jupiter System (Ecliptic)",
      "path": "/objects/solar-system/europa/",
      "coordinates": {
        "raHours": 6.002,
        "raSexagesimal": "06h 00m 07.20s",
        "decDegrees": 23,
        "decSexagesimal": "+23° 00′ 00.0″",
        "epoch": "J2000.0",
        "sourceId": "src:jpl-horizons"
      },
      "classification": {
        "primaryClass": "Galilean silicate moon with young water-ice shell and global subsurface ocean"
      },
      "measurements": [
        {
          "id": "sol:europa:vmag",
          "entityId": "sol:europa",
          "property": "apparent_magnitude_v",
          "label": "Opposition visual magnitude (V)",
          "value": 5.29,
          "unit": "mag",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.05
          },
          "method": "JPL planetary satellite photometry (geometric albedo = 0.67)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:europa:period",
          "entityId": "sol:europa",
          "property": "orbital_period_days",
          "label": "Orbital period around Jupiter",
          "value": 3.551181,
          "unit": "d",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.000001
          },
          "method": "Galilean 1:2:4 Laplace resonance ephemeris (semi-major axis = 671,100 km / 9.39 R_Jup)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:europa:radius",
          "entityId": "sol:europa",
          "property": "radius_earth",
          "label": "Mean solid radius",
          "value": 0.245,
          "unit": "R⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.0002
          },
          "method": "Galileo spacecraft limb imaging (1,560.8 ± 0.5 km, 90% of Moon's radius)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        },
        {
          "id": "sol:europa:mass",
          "entityId": "sol:europa",
          "property": "mass_earth",
          "label": "Satellite mass",
          "value": 0.008035,
          "unit": "M⊕",
          "uncertainty": {
            "kind": "symmetric",
            "plusMinus": 0.000001
          },
          "method": "Galileo & Juno flyby radio-Doppler tracking (4.7998 × 10^22 kg)",
          "sourceId": "src:jpl-horizons",
          "datasetVersion": "DE441 (2021/2026)",
          "qualityStatus": "definitive"
        }
      ],
      "sources": [
        "src:jpl-horizons",
        "src:jwst-archive"
      ]
    }
  ]
}