Earth

"Our ancestor, Assur-nasi-apli, who was known as the cruellest of the cruel, seized the throne by slaying his own father and starting the reign of the sword. His conquests included the Uramia Lake region which led him for Commagene and Khabur. His son recieved tribute from the Shuites, from Tyre, Sidon, Gebel and even from Jehu, son of Omri, whose very name struck terror into thousands. The conquests which began with Assur-nasi-apli carried arms into Media and later into Israel, Damascus, Edom, Arpad, Babylon and Umlias. Does anyone remember these names and places now? I have given you enough clues: try to name the planet."

- The Stolen Journals

Earth, also called Old Earth, Terra, or Old Terra, was the third planet located in the Sol star system. The human race originated there. It was where the Commission of Ecumenical Translators converged to assemble the Orange Catholic Bible after the Butlerian Jihad.

The planet Earth is referred to as "no longer [existing]" by the God Emperor Leto II in his Stolen Journals, and as being "gone" (along with many of mankind's other former ancestral worlds) by the Bene Gesserit Reverend Mother Darwi Odrade when conversing with the young Miles Teg ghola, which suggests that the planet is no longer inhabited by the time period of Chapterhouse: Dune (several thousand years since the era of Paul Atreides).

Other References to Earth

 * Ghanima and Leto Atreides II, in a private moment between them, speak French, implied to be nearly an extinct language.
 * The Bene Gesserit Sisterhood possessed what was thought to have been an original Vincent Van Gogh oil painting ("Thatched Cottages at Cordeville").
 * Paul Atreides suggests Stilgar look into historical references to Genghis Khan and Adolf Hitler for a comparison to Paul.
 * References to animals and plants taken from Earth and reseeded on other worlds, sometimes genetically modified (such as laza tigers)
 * The God-Emperor Leto Atreides II, through his ancestral memory, recalled many things from Earth history, including Torquemada, the Romans and Greeks, the conquests of Assur-Nasir-Apli, musicians such as Mozart, Bach and Lipallo, Napoleon, Islam, and the Jesuits.
 * Scytale knew of Earth, mentioning the Golden Age of Old Earth and the camels of the planet.
 * The Bene Gesserit drew patterns of Old Earth on many planets, sometimes only a faint sketch, but sometimes succeeding, like on Chapterhouse.