Final answer:
Nicolaus Copernicus was the first to propose the heliocentric model in 1543, fundamentally changing the understanding of the solar system and leading to the modern field of astronomy.
Step-by-step explanation:
The first person to propose the heliocentric model in 1543 was Nicolaus Copernicus. Copernicus's heliocentric model positioned the Sun, not the Earth, as the center of the solar system, which was a significant shift from the geocentric model of Ptolemy that had been widely accepted for over a millennium. Copernicus's revolutionary work, De Revolutionibus Orbium Coelestium, published in the same year of his death, laid the foundation for modern astronomy and paved the way for future astronomers like Tycho Brahe, Johannes Kepler, and Galileo Galilei to further develop and confirm the heliocentric theory through their meticulous observations and mathematical analysis of planetary motions.