The movie started with $6.5 million from previews on Thursday and is aiming for about $42.5 million in the US, even though it cost $115 million to make.
The film has a group of actors including Emily Blunt, Josh O'Connor, Colin Firth, Coleman Domingo, and Eve Hewson, but Spielberg's name is the main reason people might want to watch it.
In the last ten years, Spielberg has mostly made serious dramas like The Post and The Fabelmans, and also did the musical West Side Story. He hasn't made a movie like this, full of action and excitement, since 2018's Ready Player One, which made over $607 million worldwide.
Spielberg started the UFO movie genre with Close Encounters of the Third Kind in 1977 and came back with War of the Worlds in 2005.
The movie has good reviews, with critics giving it an 82 percent rating on Rotten Tomatoes.
David Rooney, the chief film critic at The Hollywood Reporter, said, "There are allegories that can be read about fear of the unknown breeding cruelty and exploitation, but Disclosure Day is first and foremost a propulsive yarn with thematic roots in hope, truth, empathy, and perhaps even spirituality."
Universal is opening the movie, made by Spielberg's company Amblin, in 3,824 theaters.
