You have answered this question for yourself. It was 'Nicolas Copernicus' , hencethe word 'copernican'.

Nicolaus Copernicus developed and published an astronomical model in 1543 that put the sun at the center of the universe. This model became known as Copernican heliocentrism.

The Copernican Revolution refers to the shift in scientific thought from the belief that Earth is the center of the universe (geocentrism) to the understanding that the Earth revolves around the Sun (heliocentrism). This revolution was initiated by the work of Nicolaus Copernicus in the 16th century and fundamentally changed how we perceive our place in the cosmos.

The church ordered Galileo to abandon the Copernican idea of heliocentrism because it conflicted with the prevailing biblical interpretation of a geocentric universe, where the Earth is the center of the universe. The church believed that this view would undermine the authority of the Bible and cause confusion among the faithful. Additionally, Galileo's advocacy for heliocentrism challenged the church's authority and power.