Pluto is a dwarf planet, and one of the most distant objects in the solar system. It is connected to the Shade Realm of Entropy.
Sleepers know that Pluto is a small, icy world with a proportionately large moon called Charon. There is a large hidden moon called Cerberus where the Euthanatos maintain a chantry in order to study the Shade Realm. They do not allow outsiders access, even those from their most closely allied Traditions; they do not hesitate to use force to repel the Technocracy, Marauders, or Nephandi who attempt to trespass, and none of the Traditions want to press their luck.
It has been suggested that the decision in 2006 to reclassify Pluto as a dwarf planet (alongside Ceres and Eris) was part of a Technocratic conspiracy, or perhaps an attempt by the Euthanatos themselves to further restrict access to the Shade Realm of Entropy.