Heliocentrism

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Overview

Heliocentrism is the view that the Earth and the other planets orbit the Sun, and that the Earth also turns daily on its axis. It replaced the long-standing picture in which a motionless Earth sat at the centre of the cosmos. The change mattered beyond astronomy. It showed that appearances can mislead, that careful observation and mathematics can overturn common sense, and that human beings occupy no special position in space. It also became the standard case study of conflict between new evidence and established authority.

Context

For about 1,400 years the dominant model was that of Ptolemy, a Greek-language astronomer in Roman Egypt, who explained planetary motion with circles upon circles around a still Earth. It predicted positions well enough for calendars and navigation, and it matched ordinary experience: the ground feels still and the sky appears to move. Church teaching and Aristotle's physics both supported it.