Gavin's atmosphere is composed of a liquid oxide alloy. Scientists believe Primary's Sun superheats an extremely dense metal core, which creats Gavin's unique atmosphere. The highly reflective atmosphere is poisonous to all known life (including the infamous, lifeless Deadhead), and too dense for any Cradian technology to navigate.
Due to its reflective qualities, Gavin is often viewed by more superstitious cultures and religions as being a literal connection to the psyche.
KAL-G, a highly-insulated research station, operates within Gavin's orbit, and keeps record of any anomalies.