The air was thick with emotion when Carrie Underwood, Usher, Celine Dion, Jennifer Hudson and Smokey Robinson took the stage to pay tribute to Michael Jackson, and sing along with Michael on his recording of 'Earth Song' during the Grammy Awards Sunday night. Michael's longtime friend and 'We Are The World' collaborator, Lionel Richie, introduced the singers, after which Michael's voice filled the room, to say that he hated pollution and destruction of the earth ...

"That stuff really bothers me ... that's why I write these kinda songs, to give some kind of awareness and awakening and hope to people. I love the planet. I love trees. When the colors are changing in the leaves, I love it ... "

The performance that followed was set against a 3-D mini-movie, which was featured in Michael's 'This Is It' film. Michael's vocals were perfectly intertwined with those of the emotional vocals of the performers on the Grammy stage. At the end of the song, they all turned their backs to a spellbound audience to gaze reverently up at Michael's image, displayed high above the stage.

The moment was electric with emotion ... even during rehearsal, the day before.

"It's so bittersweet, of course," Carrie tells ETOnline. "I think we were all really feeling it when we were in rehearsal and on the stage practicing. The stuff that's going on behind us on the screen is absolutely heartwrenching and amazing. And towards the end, we all turn around ... and it's not about us, we don't even take the applause ... we just turn around and look up at Michael. It's just an amazing moment."

Immediately following the performance, Michael's children, Prince Michael and Paris, came onstage to an emotional outpouring of applause, to accept a Grammy lifetime-achievement award for their father.

"Our father was always concerned about the planet and humanity," Prince Michael, 12, said. "Through all his hard work and dedication, he has helped many charities and donated to all of them. Throughout his songs, his message was simple -- love. We will continue to spread his message and help the world. Thank you. We love you, Daddy."