{
  "meta": {
    "source": "NASA Planetary Fact Sheet (selected values, rounded)",
    "notes": "Core physical/orbital values are approximate and intended for educational UI display."
  },
  "planets": [
    {
      "id": "mercury",
      "name": "Mercury",
      "symbol": "☿︎",
      "classification": "Terrestrial planet",
      "summary": "The smallest planet and closest to the Sun, with extreme day/night temperature swings.",
      "meanDistanceFromSun": {
        "kmMillions": 57.9,
        "au": 0.387
      },
      "orbitalPeriod": {
        "days": 87.969,
        "years": 0.241
      },
      "rotationPeriodHours": 1407.6,
      "radiusKm": 2439.7,
      "diameterKm": 4879.4,
      "massKg": 3.3011e23,
      "gravityMs2": 3.7,
      "escapeVelocityKms": 4.25,
      "axialTiltDeg": 0.03,
      "averageTempC": 167,
      "moons": 0,
      "atmosphere": "Extremely thin exosphere (oxygen, sodium, hydrogen, helium, potassium).",
      "notableFacts": [
        "A solar day lasts about 176 Earth days.",
        "Its surface is heavily cratered like Earth’s Moon."
      ]
    },
    {
      "id": "venus",
      "name": "Venus",
      "symbol": "♀︎",
      "classification": "Terrestrial planet",
      "summary": "Earth-sized but shrouded in dense clouds, with a runaway greenhouse effect.",
      "meanDistanceFromSun": {
        "kmMillions": 108.2,
        "au": 0.723
      },
      "orbitalPeriod": {
        "days": 224.701,
        "years": 0.615
      },
      "rotationPeriodHours": -5832.5,
      "radiusKm": 6051.8,
      "diameterKm": 12103.6,
      "massKg": 4.8675e24,
      "gravityMs2": 8.87,
      "escapeVelocityKms": 10.36,
      "axialTiltDeg": 177.36,
      "averageTempC": 464,
      "moons": 0,
      "atmosphere": "Very dense carbon dioxide with sulfuric acid clouds.",
      "notableFacts": [
        "Hottest planetary surface in the Solar System.",
        "Rotates retrograde (east-to-west)."
      ]
    },
    {
      "id": "earth",
      "name": "Earth",
      "symbol": "⊕",
      "classification": "Terrestrial planet",
      "summary": "The only known world with stable liquid water oceans and life.",
      "meanDistanceFromSun": {
        "kmMillions": 149.6,
        "au": 1.0
      },
      "orbitalPeriod": {
        "days": 365.256,
        "years": 1.0
      },
      "rotationPeriodHours": 23.934,
      "radiusKm": 6371,
      "diameterKm": 12742,
      "massKg": 5.97237e24,
      "gravityMs2": 9.807,
      "escapeVelocityKms": 11.186,
      "axialTiltDeg": 23.44,
      "averageTempC": 15,
      "moons": 1,
      "atmosphere": "Mostly nitrogen and oxygen.",
      "notableFacts": [
        "About 71% of the surface is covered by water.",
        "Plate tectonics helps regulate long-term climate."
      ]
    },
    {
      "id": "mars",
      "name": "Mars",
      "symbol": "♂︎",
      "classification": "Terrestrial planet",
      "summary": "A cold desert planet with the largest volcano and canyon in the Solar System.",
      "meanDistanceFromSun": {
        "kmMillions": 227.9,
        "au": 1.524
      },
      "orbitalPeriod": {
        "days": 686.98,
        "years": 1.881
      },
      "rotationPeriodHours": 24.623,
      "radiusKm": 3389.5,
      "diameterKm": 6779,
      "massKg": 6.4171e23,
      "gravityMs2": 3.721,
      "escapeVelocityKms": 5.03,
      "axialTiltDeg": 25.19,
      "averageTempC": -63,
      "moons": 2,
      "atmosphere": "Thin carbon dioxide atmosphere.",
      "notableFacts": [
        "Home to Olympus Mons and Valles Marineris.",
        "Evidence suggests ancient liquid water on its surface."
      ]
    },
    {
      "id": "jupiter",
      "name": "Jupiter",
      "symbol": "♃︎",
      "classification": "Gas giant",
      "summary": "The largest planet, with powerful storms and a deep atmosphere of hydrogen and helium.",
      "meanDistanceFromSun": {
        "kmMillions": 778.6,
        "au": 5.203
      },
      "orbitalPeriod": {
        "days": 4332.59,
        "years": 11.86
      },
      "rotationPeriodHours": 9.925,
      "radiusKm": 69911,
      "diameterKm": 139822,
      "massKg": 1.8982e27,
      "gravityMs2": 24.79,
      "escapeVelocityKms": 59.5,
      "axialTiltDeg": 3.13,
      "averageTempC": -110,
      "moons": 95,
      "atmosphere": "Mostly hydrogen and helium.",
      "notableFacts": [
        "The Great Red Spot is a centuries-old storm.",
        "Its magnetic field is the strongest of any planet."
      ]
    },
    {
      "id": "saturn",
      "name": "Saturn",
      "symbol": "♄︎",
      "classification": "Gas giant",
      "summary": "Known for its bright ring system made largely of ice particles.",
      "meanDistanceFromSun": {
        "kmMillions": 1433.5,
        "au": 9.537
      },
      "orbitalPeriod": {
        "days": 10759.22,
        "years": 29.45
      },
      "rotationPeriodHours": 10.656,
      "radiusKm": 58232,
      "diameterKm": 116464,
      "massKg": 5.6834e26,
      "gravityMs2": 10.44,
      "escapeVelocityKms": 35.5,
      "axialTiltDeg": 26.73,
      "averageTempC": -140,
      "moons": 146,
      "atmosphere": "Mostly hydrogen and helium.",
      "notableFacts": [
        "Its average density is lower than water.",
        "Rings are broad but extremely thin."
      ]
    },
    {
      "id": "uranus",
      "name": "Uranus",
      "symbol": "♅︎",
      "classification": "Ice giant",
      "summary": "An ice giant that rotates on its side relative to its orbital plane.",
      "meanDistanceFromSun": {
        "kmMillions": 2872.5,
        "au": 19.191
      },
      "orbitalPeriod": {
        "days": 30688.5,
        "years": 84.02
      },
      "rotationPeriodHours": -17.24,
      "radiusKm": 25362,
      "diameterKm": 50724,
      "massKg": 8.681e25,
      "gravityMs2": 8.69,
      "escapeVelocityKms": 21.3,
      "axialTiltDeg": 97.77,
      "averageTempC": -195,
      "moons": 28,
      "atmosphere": "Hydrogen, helium, methane.",
      "notableFacts": [
        "Its sideways tilt likely comes from an ancient giant impact.",
        "Methane in the atmosphere gives it a blue-green color."
      ]
    },
    {
      "id": "neptune",
      "name": "Neptune",
      "symbol": "♆︎",
      "classification": "Ice giant",
      "summary": "A distant, dynamic world with supersonic winds and dark storm systems.",
      "meanDistanceFromSun": {
        "kmMillions": 4495.1,
        "au": 30.07
      },
      "orbitalPeriod": {
        "days": 60182,
        "years": 164.8
      },
      "rotationPeriodHours": 16.11,
      "radiusKm": 24622,
      "diameterKm": 49244,
      "massKg": 1.02413e26,
      "gravityMs2": 11.15,
      "escapeVelocityKms": 23.5,
      "axialTiltDeg": 28.32,
      "averageTempC": -200,
      "moons": 16,
      "atmosphere": "Hydrogen, helium, methane.",
      "notableFacts": [
        "Fastest sustained winds measured on any planet.",
        "Triton, its largest moon, orbits in retrograde."
      ]
    },
    {
      "id": "pluto",
      "name": "Pluto",
      "symbol": "♇︎",
      "classification": "Dwarf planet",
      "summary": "A Kuiper Belt dwarf planet with nitrogen ice plains and a complex seasonal cycle.",
      "meanDistanceFromSun": {
        "kmMillions": 5906.4,
        "au": 39.48
      },
      "orbitalPeriod": {
        "days": 90560,
        "years": 248.0
      },
      "rotationPeriodHours": -153.3,
      "radiusKm": 1188.3,
      "diameterKm": 2376.6,
      "massKg": 1.303e22,
      "gravityMs2": 0.62,
      "escapeVelocityKms": 1.21,
      "axialTiltDeg": 122.53,
      "averageTempC": -225,
      "moons": 5,
      "atmosphere": "Thin, variable nitrogen atmosphere with methane and carbon monoxide.",
      "notableFacts": [
        "Charon is large enough that Pluto-Charon is often described as a binary system.",
        "First close-up images were captured by New Horizons in 2015."
      ]
    }
  ]
}