Figure 6-1The Sun and the Planets In this figure, photographs of the eight planets are shown to size scale. From left to right: The four planets that orbit nearest the Sun (Mercury, Venus, Earth, and Mars) are small and made of rock and metal. The next two planets (Jupiter and Saturn) are large and composed primarily of hydrogen and helium. Uranus and Neptune are intermediate in size and contain roughly equal amounts of ices, hydrogen and helium, and terrestrial material.