In The Whisperer in Darkness, Yuggoth is identified as an outpost on Pluto.
The story presents Yuggoth as a distant world associated with the Mi-Go, an extraterrestrial race of fungoid beings. The alien visitors describe journeys between Earth and Yuggoth, and they try to persuade Albert Wilmarth to join them. Their technology includes devices that can remove and preserve a human brain in a cylinder for transport and communication.
Lovecraft wrote the novella from February to September 1930, and Weird Tales published it in August 1931. In the story's cosmic geography, Yuggoth is not merely an abstract dimension: it is treated as a physical planetary outpost at the edge of the solar system.
The name is often connected with Pluto, which had been discovered in 1930, shortly before Lovecraft completed the story. A common mix-up is assuming Yuggoth is Cthulhu's home world or a purely mythological realm. In this tale, its key association is with the Mi-Go and their operations beyond Earth.