"The most fascinating explanation of this mystery body, which is so cold it casts no light and
has never been seen by optical telescopes on Earth or in space, is that it is a giant gaseous
planet as large as Jupiter and as close to Earth as 50 trillion miles. While that may seem like a
great distance in earthbound terms, it is a stone’s throw in cosmological terms, so close in fact
that it would be the nearest heavenly body to Earth beyond the outermost planet Pluto."
https://www.timetobelieve.com/2013/01/planet-x-in-washington-post-1983/