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Scientists discovered the Solar System’s third zone because of Pluto
While Pluto's icy neighbours are to blame for the planet's demise, they are also part of what makes the New Horizons mission so interesting. "Pluto may be the star witness to the entire third zone of the solar system," NASA's Jeff Moore told TIME. The solar system was thought to be divided into two zones until the Kuiper Belt was discovered: the inner zone, which contained the rocky planets from Mercury to Mars, and the outer zone, which contained the gas giants from Jupiter to Neptune. Pluto, on the other hand, introduced astronomers to the third zone of our solar system, which Moore described as a "vast region of ice planets."