Astronomers argue that there’s an undiscovered giant planet far beyond the orbit of Neptune. A newly discovered rocky body has added evidence to the circumstantial case for it.
About the author
Shannon Hall is a freelance science journalist based in the Rocky Mountains. She has bachelor’s degrees in astrophysics and philosophy and master’s degrees in astrophysics and science reporting. Her work has appeared in Scientific American, The New York Times, National Geographic, Nature, Discover, Sky & Telescope, New Scientist and other publications.