This visualization animates a sunrise and sunset over a layered mountain landscape using only SVG elements and SMIL animations. A sky gradient transitions from aliceblue to indigo as a sun circle moves downward and back, while two terrain paths with linear gradients shift color to simulate changing light. The scene uses inline `<animate>` tags within SVG `radialGradient` and `linearGradient` definitions to cycle colors and the sun’s `cy` position over 15-second loops. No JavaScript or D3 is involved; rendering relies entirely on native SVG markup.