Learn why NASA scientists are so excited about all three of this year’s essay contest topics. All three of these moons are interesting to planetary scientists, because they have each been observed on only one side. What does the back of each of these moons look like? We don’t know! And neither does anyone else... yet.


Topic 1: Miranda, Moon of Uranus

Miranda, the fifth largest moon of Uranus, has only been explored so far by NASA’s Voyager 2 spacecraft in 1986. Its Frankenstein-like surface appears to be cobbled together from many types of rock and ice.

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Topic 2: Triton, Moon of Neptune

Triton, the largest moon of Neptune, has nitrogen ice on its surface and a core made of rock and metal. Triton is volcanically active, and it has a very thin nitrogen atmosphere. NASA’s Voyager 2 spacecraft flew by Triton in 1989.

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Topic 3: Charon, Moon of Pluto

Charon is the largest moon of the dwarf planet, Pluto. The New Horizons spacecraft flew by Charon in July 2015.

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