DRoP-edia

Historical synopsis

Pern was colonised by settlers from Earth who wanted to return to an agrarian society with a low level of technology. The name was originally an acronym: Parallels Earth Resources Negligible (i.e., insufficient to support interstellar commercial investment). Shortly after the first colony was established, the settlers were devastated to discover that their chosen planet was not a safe place. Pern is subject to periodic attack from space by the destructive Thread, a spaceborne spore that destroys organic substances on contact. Unable to retreat from the peril, the settlers developed methods of combating the Thread. "Holds" were dug into the cliffs for them to live in, and Pernese scientists "upgraded" a local reptilian lifeform, the fire-lizard, into full-sized flame-breathing telepathic dragons, who were able to sear the Thread before it could fall to the ground. Dragonriders became a vitally important and highly respected profession, living in Weyrs, and as time progressed, the settlers forgot their Terran origins.

Planetary system data

Pern is the third of five planets in the Rukbat system (the Pernese star is also known as Alpha Sagittarius). In a departure from reality, Rukbat is a class G (yellow) star in the series; the real Rukbat is a blue, class B star -- although it could be that the star Pern orbits is simply a solar-type star that is near the real Rukbat which was given the brighter star's name for convenience. Pern has two moons, Belior and Timor (in order of distance). The Rukbat system in the novel also contains two asteroid belts and an Oort cloud. The Oort cloud and a rogue "sixth" planet, the Red Star (a Sedna-class inner Oort cloud object), play a major role in the series, as they are the source of Thread.

Geography

Pern bears three continents, four major oceans, and a large number of islands. The largest continent, the Southern, is noted for large areas of grassland and jungle, as well as high tectonic and volcanic activity (probably due to the two moons, although this increases with the coming of the Red Star). The Northern Continent, in contrast, is relatively infertile composed primarily of 'shield' bedrock and is the most tectonically stable landmass on the planet. Not much is known of the small Far Western Continent, as it has never been explored; its existence is known only from orbital satellite surveys and maritime expeditions.

Pern is noted for its high incidence of cave systems, particularly in the Northern Continent. This feature heavily influenced the development of human society on the planet, as humans forced to take shelter in these caves eventually developed an intricate culture associated with cave-dwelling in a feudal society at a medieval - Renaissance level of technology.

Pern is relatively lacking in most major metals. Nonetheless, sufficient deposits of petroleum and metals exist to supply a high-technology agrarian society, though not a high-technology industrial one.

Although Pern has four major oceans, the only ocean of major concern to most inhabitants of Pern is the Southern, which separates the Northern and Southern Continents. Few expeditions have explored the Western and Eastern Oceans to either side of the main continents, and the Ring Sea is known only from satellite observations.

The Southern Ocean is noted for its volatile weather and strong currents, which present a challenge for mariners. At least one tropical cyclone has occurred in the ocean in the course of the books.

Ecology

Pernese biomes have been profoundly affected by the cyclical appearance of Thread, a spore which destroys organic material. This has resulted in a relative dearth of terrestrial plants and animals. However, as Thread drowns in water, Pern has a much more populous and thriving aquatic ecology.

Pernese biomes contain both indigenous Pernese flora and fauna and introduced species from other worlds -- primarily Earth. (The original EEC team found that there was very little biodiversity, meaning that the colonists, coming two hundred years later, brought flora and fauna species with them.)

Thread!

Thread is a non-sentient life-form. Its sole purpose is to reproduce, which it does by consuming carbon--plants, animals, humans, clothing, soil...anything organic. When colonists first settled Pern, they noticed huge circular acreages where the plant life within was younger (sometimes several decades younger) than surrounding vegetation--that's what happens when Thread reaches the ground.

It burrows into the ground and builds a huge "nest" just under the surface which, when broken open, reveals a mass of Thread strands that look like a cat got ahold of a ball of yarn and tried to unravel it without finding the ends. The stuff writhes and is iridescent in color. It eats everything organic that it comes in contact with, which means plants lose all their roots and begin whithering immediately; a "single" strand can devour a herdbeast (cow) in under two minutes--as each strand eats, it grows in diameter, and when each strand gets enough food, it splits into two strands, growing exponentially. Animals caught in the "circle of death" will collapse the thin surface layer of dirt and be consumed by the Thread underneath.

Oddly, once Thread burrows reach a certain size, they begin to die, from the center out. It doesn't take much for Thread to starve to death, and the resulting...mass...is a sickly-smelling tar-like pool. Once the center begins to die, death comes quickly to the rest of the burrow; this is where the second--infrequently referenced and relatively unstudied--life cycle begins. The outer strands of a burrow break down into thousands of smaller strands, about the size of the last joint of your pinkie finger. These seem to be relatively harmless, and no permanent effect from them has ever been noted.

My personal theory about these "Thread grubs" is that the tar-like substance left from the dying Thread burrow is what would, in a zero-G or low-G environment (like that of the Red Star or the Oort Cloud) form the outer shell of the Thread ovoids, allowing the organism to penetrate the atmosphere, with the "grubs" contained inside, but in the higher gravity of Pern--and with the abundance of organic life--the "grubs" cannot seek shelter within the "tar" of their predecessors.