### Instruction: What is heliocentrism?
### Response: Heliocentrism is an astronomical model in which the sun lies at the center, and planets revolve around it. The model was published by Nicolaus Copernicus shortly before his death in 1543, and became one of the most significant events in the history of science. Before the acceptance of heliocentrism, it was widely believed that Earth was the center of the entire universe.