What is the heliocentric theory?
The heliocentric theory is/was the theory that is the center of .
“helios” is the Greek word for sun.
The heliocentric theory replaced the geocentric theory; in the geocentric theory the earth (“geo”) was modeled as the center of the universe.
The heliocentric model is often still employed when limited to our solar system but is no longer accepted as a working model for the universe.