Weyr

A Weyr /ˈwɪər/ is a collection of dragons, their riders and support staff in Anne McCaffrey's fictional world of Pern.

The function of a Weyr is to fight Thread, a spore that originates in the Oort cloud of the Rukbat solar system, carried by a planetoid referred to as the Red Star with a loose elliptical orbit. The time during which Thread falls is called a Pass. These Passes last about 50 years, usually with a break of 200 years between, although extended periods have been known to occur due to orbital mechanics.

Geology

Weyrs are also the physical spaces in which dragons, their riders and support staff reside. Weyrs are usually built into the cliff faces of ancient volcanic calderas. Many of the living spaces are in natural cave systems within the cliff walls, but in early Passes when the colonists still had technology, plasma cutters were used to create extended systems and additional caves to meet the needs of the growing numbers of dragons. There are six ancient Weyrs as of beginning of the 9th Pass.