Seven red bursts that appeared across the galaxy in 2257, created by a time traveller to guide Discovery toward preventing the extinction of all sentient life.
The Red Angel signals were seven red bursts of light that appeared without warning at points across the galaxy in 2257. Each signal was linked to sightings of a mysterious figure known as the Red Angel, who appeared at moments of crisis and seemed to intervene to save lives.
In the second season of Star Trek: Discovery, Christopher Pike takes command of the USS Discovery to investigate. The signals lead the crew to places such as Terralysium, Kaminar and Xahea, while Spock, who had visions of the Red Angel, becomes central to the mystery. The figure turns out to be a human in a time travel suit. Michael Burnham's mother, Gabrielle Burnham, had been thrown into the future by the suit, and Michael herself creates the signals, all as part of an effort to stop Control, a rogue artificial intelligence, from wiping out sentient life.
The arc ends with Burnham leading Discovery into the far future, which takes the sphere data out of Control's reach and sets up the series' move to the 32nd century.