The theory that explains the origin of the universe through a massive explosion is known as the Big Bang Theory. This model proposes that the universe began approximately 13.8 billion years ago from a hot, dense state and has been expanding ever since. The theory is supported by several lines of evidence, including the cosmic microwave background radiation and the observed redshift of distant galaxies. The Big Bang Theory provides a comprehensive framework for understanding the formation and evolution of astronomical structures and cosmic phenomena.