A spectacular eruption from a protostar that recurs every eleven years and is held sacred by pilgrims, whom Enterprise joined to witness it in 2151.
The Great Plume of Agosoria is a stellar phenomenon seen in the Enterprise episode Cold Front. A protostar inside a nebula throws out an immense plume of matter once every eleven years.
A religious order makes pilgrimages to watch it, believing the plume to be a renewal of the moment at which the universe began. In 2151 Enterprise meets a transport full of pilgrims on the way and Archer invites them aboard to view the event from the ship.
One of the guests is the Suliban Silik in disguise, who secretly prevents an accident that would have destroyed Enterprise. The crewman Daniels then reveals himself to Archer as an agent from the future, making the visit the crew's first clear look at the Temporal Cold War.