The 11 recognized planets are Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto and Eris. Ceres, Pluto and Eris are considered dwarf planets.
National Geographic Children's Books created the contest in response to the recent announcement about the planets.
The Riverview Elementary School student's mnemonic will be published in astronomer David Aguilar's next National Geographic book, "11 Planets: A New View of the Solar System."
It also will be recorded into a song by Grammy-nominated singer and songwriter Lisa Loeb.
Both are scheduled to be released in March.
