A nuclear explosion occurs when a nuclear weapon detonates, releasing a massive amount of energy in the form of an explosion. This energy comes from nuclear reactions, either fission (splitting heavy atomic nuclei) or fusion (combining light atomic nuclei). The explosion produces a fireball, shockwave, and intense heat, causing widespread destruction and loss of life. The effects of a nuclear explosion can be devastating. The immediate blast can flatten buildings and create a lethal radius, while the heat can ignite fires over large areas. Additionally, radioactive fallout can contaminate the environment, posing long-term health risks to those exposed. Understanding the science behind nuclear weapons is crucial for global security and disaster preparedness.