The Big Bang is the leading scientific explanation for the origin of the universe. It suggests that around 13.8 billion years ago, the universe began as an extremely hot and dense point, which then rapidly expanded. This expansion caused the universe to cool, allowing particles to form and eventually leading to the creation of atoms. As the universe continued to expand, these atoms combined to form stars and galaxies. Over billions of years, the universe evolved, giving rise to the vast cosmos we observe today, filled with galaxies, stars, and planets.