Some time in the third century BC, a fellow by the name of Aristarchus of Samos wrote a book in which he said the earth moved around the sun. The book's lost. We know about it because Archimedes quoted it with approval in a book of his own called

Archimedes clearly bought into the theory. He wrote

Archimedes finishes:

*The Sand Reckoner*.Aristarchus of Samos brought out a book in which the universe is many times greater than that now so called. His hypothesis is that the fixed stars and the sun remain unmoved, that the earth revolves about the sun in the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same center as the sun, is so great that the circle in which he supposes the earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface.That beats Copernicus by about 1,700 years. It's when you read things like this that you realize how much was lost when the classical world collapsed.

Archimedes clearly bought into the theory. He wrote

*The Sand Reckoner*to work out how many grains of sand it would take to fill up the universe, assuming Aristarchus was right. The numbers were so huge that to do it, Archimedes had to invent a whole new number system. The number of he got, in modern notation, was 8 x 10^{63}grains of sand, which is amazingly close to modern estimates for the number of known particles (though obviously we now know about massive amounts of vacuum too).Archimedes finishes:

I conceive that these things will appear incredible to the great majority of people who have not studied mathematics, but that to those who are conversant therewith and have given thought to the question of the distances and sizes of the earth, the sun and moon and the whole universe, the proof will carry conviction. And it was for this reason that I thought the subject would not be inappropriate for your consideration.