What are examples of scientific theories that have changed?

Examples of scientific theories that have changed include the geocentric model, which posited that the Earth was the center of the universe, replaced by the heliocentric model that identifies the Sun as the center of our solar system. Another example is the theory of spontaneous generation, which suggested that living organisms could arise from non-living matter; this was debunked by experiments demonstrating that life arises from existing life. Additionally, the understanding of the atom has evolved significantly, from Dalton's solid sphere model to the current quantum mechanical model that describes complex interactions and behaviors.