The Crack In The Sky, also known as The Crack was an in-game entity that spawned late in Season 4 (June 30th 2018, Blast Off Event) And disappeared after spawning The Cube (Aug 24, 2018, Crack Closure Event).
The Crack formed after the Blast Off event of Season 4. It expanded until the end of Season 4 spawning Rifts. During Season 5 the Crack started to shrink. After a while, the Crack started to shoot Purple Lightning into the Greater Paradise Palms area the lightning formed into The Cube. After The Cube formed, the Crack quickly closed.