How confident can astronomers be that the big bang theory is correct?

Astronomers have a high level of confidence in the Big Bang theory due to multiple lines of evidence supporting it, such as the observed expansion of the universe, the cosmic microwave background radiation, and the abundance of light elements like hydrogen and helium. These observations are consistent with predictions made by the theory. While science always allows for new evidence and theories, the Big Bang remains the leading explanation for the origin of the universe due to its robust framework and successful predictions.