Final answer:
Nicolaus Copernicus investigated a sun-centered, or heliocentric, model of the universe, differing from the Earth-centered Ptolemaic view.
Step-by-step explanation:
Nicolaus Copernicus, influenced by his studies and religious beliefs, was motivated to investigate a sun-centered model of the universe. This model, known as the heliocentric model, proposed that the Sun is at the center of the solar system, which was a significant shift from the then-prevailing Ptolemaic model that placed Earth at the center. Copernicus's heliocentric model was revolutionary because it provided a simpler and more accurate understanding of the solar system, aligning with observations better than the geocentric Ptolemaic model could.
The heliocentric model also paved the way for further developments in astronomy, including the work of Kepler and Newton in understanding planetary motions and gravity, respectively.