He attempted to calculate the sizes and distances of the Sun and Moon, establishing that the Sun is much larger than the Earth and much farther off than the Moon. To Aristarchus is due the first heliocentric theory. He placed the Sun at the centre of the Earth’s orbit, and the fixed stars on a sphere a great distance from the Sun. The theory attracted little support mainly because Aristotle’s geocentric theory was held in high esteem, but also because the idea of a moving Earth was disliked.