Pluto is now called a "dwarf planet." Its orbit is farther from the Sun than Neptune's—most of the time. Sometimes its elongated orbit around the Sun puts Pluto inside the orbit of Neptune. Pluto orbits in a region of the solar system called the Kuiper [KI-per] belt, along with thousands of other icy objects. Pluto is made mostly of water ice. Deep inside are heavier iron and rock.
This image by the Hubble Space Telescope.
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