A distant planet may lurk far beyond Neptune
If Planet X exists, it may be anywhere from 250 to 1,000 times as far from the sun as Earth
THE LOST WORLD A hidden planet (foreground) might lurk in the uncharted realms of the solar system, leaving clues to its existence only in the orbits of dwarf planets or of chunks of ice in the outer edges of the Kuiper belt.
Nicolle Rager Fuller
Out beyond Neptune, the solar system resembles the deep ocean: dark, remote and largely unexplored.