Tides are the periodic rise and fall of ocean water on Earth caused by the gravitational pull of the Moon and the Sun. The core cause lies in "tidal force"—the difference in the gravitational pull of celestial bodies (mainly the Moon and the Sun) on different points on Earth. Although small, the Moon is closest to Earth, and its tidal force is more than twice that of the Sun, making it the dominant force. When the Moon, Earth, and Sun are aligned (new moon, full moon), the tidal forces of the Moon and the Sun combine, forming a "spring tide"; when they are at right angles (first quarter, last quarter), the tidal forces partially cancel each other out, forming a "neap tide." This is not only a magnificent natural phenomenon but also contains enormous tidal energy, a renewable and clean energy source. Our interactive exhibit on "Tides" uses a sophisticated three-sphere model of the Sun, Earth, and Moon to make this complex celestial mechanics process clear and operable. At the center of
