Helios is a Greek word and in that language the word is used for the sun. You can find the word as a prefix in various terms ands the prime among them are heliocentric and heliocentrism.
Heliocentrism is a belief that says that the sun is located at the centre of the universe and also of the solar system. This theory was first proposed by Aristarchus of Samos but unfortunately his writings were lost but the information he provided were crucial to the development of the theory. Later some other thinker provided some important information about the theory and most notable among them was Archimedes. He is considered more important because he lived in the third century BC and considered as the contemporary of Aristarchus.
Heliocentrism is a belief that says that the sun is located at the centre of the universe and also of the solar system. This theory was first proposed by Aristarchus of Samos but unfortunately his writings were lost but the information he provided were crucial to the development of the theory. Later some other thinker provided some important information about the theory and most notable among them was Archimedes. He is considered more important because he lived in the third century BC and considered as the contemporary of Aristarchus.