COMPOSITION Neptune's composition predominantly consists of hydrogen (around 80%) and helium (around 19%). The remaining composition includes trace amounts of methane, water, ammonia, and other ices, along with rocky materials comprising a dense core at its center. Its blue appearance is due to methane absorbing red light, reflecting blue hues. This icy giant's atmosphere also contains clouds made of methane, ammonia, and water vapor, contributing to its dynamic weather patterns and vibrant appearance.