The Great Plume of Agosoria was the religious term used by Borothan pilgrims to describe a neutron blast that was emitted by a specific protostar within a stellar nursery every eleven years. The Borothans believed this to be a sacred event, as it represented the continuing cycle of creation, with the stellar nursery in which it occurred being the location where the universe was formed. Groups of Borothan pilgrims would book passage aboard a transport ship to witness the event first-hand.
When the Plume reached its full brilliance, it was custom to drink a beverage known as voo-sinteel, as it "enhances the experience". Another tradition was the "Invocation of Renewal", a Borothan prayer that the entire group would recite during the occurrence of the Plume.
In 2151, officers aboard the NX-class Enterprise were also witness to this event when Captain Jonathan Archer invited a group of Borothan pilgrims to watch the Plume from the mess hall of the Starfleet ship. Unfortunately, Archer and several members of his crew were unable to observe the Plume as they discovered that Silik, a Suliban, had arrived aboard Enterprise disguised as a Borothan pilgrim. (ENT: "Cold Front", "Detained")