At a little before 11:30 p.m. Eastern time Jan. 2, like a lightning bolt striking a Joshua tree, the annual music festival season commenced with a tweet. Promoter Goldenvoice had spoken, and lo: Childish Gambino, Tame Impala and Ariana Grande would headline the 2019 Coachella Music and Arts Festival. Joining them will be an exuberantly broad undercard that includes Spanish flamenco-pop breakout Rosalia, Nashville singer and songwriter Kacey Musgraves, Compton rapper YG, British electronic music innovator Aphex Twin, R&B breakout H.E.R., singer-songwriter Mac DeMarco, next-wave pop innovator Janelle Monae and dozens more. The event will take place in Indio, Calif., with identical lineups across the weekends of April 12 and April 19.