Final answer:
The heliocentric system is a model of the solar system with the Sun at the center, proposed by Nicolaus Copernicus in the 16th century. It explains the motions of the planets and their order of distance from the Sun. Copernicus' ideas were initially met with resistance but later gained support through further research.
Step-by-step explanation:
The heliocentric system is a model of the solar system that places the Sun at the center, with the planets including Earth orbiting around it. This system was proposed by Nicolaus Copernicus in the 16th century. Copernicus challenged the prevailing geocentric (Earth-centered) system and suggested that the Sun was actually at the center of the universe.
With the heliocentric model, Copernicus was able to explain the complex retrograde motions of the planets without using complicated epicycles. He also correctly ordered the planets in terms of their distance from the Sun and deduced that the closer a planet is to the Sun, the faster it orbits.
Although Copernicus' ideas were not widely accepted during his lifetime, they sparked further research and investigation. The heliocentric model was later supported by the precise observations of Tycho Brahe, the mathematical laws formulated by Johannes Kepler, and the telescopic observations of Galileo Galilei.