The alighting is an anticipated event in The CW science fiction series Roswell, New Mexico. Noah Bracken describes the alighting as the victors of the war on their home planet coming for Max Evans, and presumably returning to their home world.
Noah first mentions the alighting in his confrontation with Max in the turquoise mines. It's the reason he keeps Max, Michael, and Isobel alive, since he can leverage them in return for a ride back to their home world.
Max tells Liz Ortecho about it the following morning. Rosa Ortecho later mentions that the man in her nightmares (Noah) mentioned an alighting, and Liz realizes that Rosa is receiving memories from Max.
|Max:||"Why are you keeping us alive? What are you leveraging us for?"|
|Noah:||"The alighting. They're coming for us, Maximo. I'd hoped we could go as a family, but... plans change."|
|Max:||"What's the alighting? Who are "they"?"|
|Noah:||"I told you when we left. Our home was ravaged by war. They are the ones who were victorious. Whichever side won, they'd never just leave us here. Well... they'd never leave you here."|
|Max:||"Why me? What do they want with me?"|
|Noah:||"You're the savior. Now that you're all grown up, they'll come. Maybe not this year or the next, but it doesn't matter."|
- "He said I'm some kind of savior. That the victors of the war on our home planet would come for me. He called it the "alighting"."
- ―Max to Liz, episode 2.01