Kirby Runyon, a PhD candidate in planetary geology at the Johns Hopkins University, and co-authors are proposing to rewrite the textbooks to say that the Solar System has 110 planets. Every discovered planet in the Solar System under 10,000 km in diameter, to scale. The geophysical definition of planet includes 110 known planets. Image credit: Emily Lakdawalla, Planetary Society / K.D. Runyon et al. Runyon and his colleagues argue for a definition...
