This paper provides a comprehensive scientific analysis of Jupiter’s internal structure, challenging the long-standing but incomplete notion of the planet as a simple “gas giant.” Traditionally described as a vast sphere of swirling gases surrounding a compact, solid core, Jupiter is revealed—through decades of observation and recent advances—as a world of extraordinary physical and chemical complexity. Drawing on data from NASA’s Juno mission, along with historical insights from Pioneer, Voyager, and Galileo, this study integrates spacecraft measurements, gravitational mapping, and theoretical models of planetary formation to construct a modern understanding of Jupiter’s composition. The analysis demonstrates that beneath the planet’s iconic cloud tops lies a 20,000-kilometer-deep ocean of liquid hydrogen, which under immense pressure transitions into metallic hydrogen—an exotic, electrically conductive fluid responsible for generating the strongest planetary magnetic field in the solar system. Perhaps the most transformative discovery comes from Juno’s gravitational data: Jupiter’s core is not a compact, rocky sphere, as classical models proposed, but a diffuse, “fuzzy” region extending across nearly half of the planet’s diameter. This core consists of a turbulent mixture of rock, metal, and multiple hydrogen phases, with no distinct boundaries—an architecture that defies traditional planetary formation theories. By examining the Shoemaker-Levy 9 comet impact of 1994, this paper further illustrates how external events reveal the planet’s internal chemistry and dynamics. Together, these findings compel a fundamental reassessment of how gas giants form and evolve, reshaping our broader understanding of planetary science, the behavior of matter under extreme conditions, and the origins of planetary systems across the universe.