Portal:Discworld/Article of the day/12

Article of the day

The Discworld is the setting for all of Terry Pratchett's Discworld fantasy novels. It consists of a slightly convex disc, complete with edge-of-the-world drop-off and consequent waterfall. The disc rests on the backs of four huge elephants (named Berilia, Tubul, Great T'Phon, and Jerakeen), who are standing on the back of an enormous turtle, named Great A'Tuin, as it slowly swims through space. The Discworld is a fantasy land in the Tolkien and Brothers Grimm mould, complete with witches, wizards, dragons, trolls, and dwarfs; however, over time it has largely evolved into its own distinct culture, as its denizens find more sophisticated ways to outgrow their narrative conventions. The Disc is heavily influenced by magic and, while having similarities to (and in some cases, based on) planet Earth, it conforms to its own laws of physics.

The narration has described A'Tuin as "the only turtle ever to feature on the Hertzsprung-Russell diagram." The substance it swims through is called aether, and may be identical to the ancient Greek mythical fifth element of the same name, or to the 19th century concept of luminiferous aether. The idea for a world supported by elephants on top of a giant turtle was first mentioned by British philosopher John Locke when questioning the source of knowledge. Great A'Tuin frequently rolls on its belly to avoid asteroid and comet collisions, or even to snatch these projectiles out of the sky. This doesn't affect the Disc's population, other than to induce severe seasickness on anyone who happens to be looking at the night sky at that time. Due to Great A'Tuin's traveling through the universe, the night sky of the Discworld changes markedly over the course of decades, as the turtle departs older constellations and enters new ones. This means that astrologers must constantly update and alter their horoscopes to incorporate all-new zodiacs.