<P> According to Al - Biruni, Sijzi invented an astrolabe called al - zūraqī based on a belief held by some of his contemporaries "That the motion we see is due to the Earth's movement and not to that of the sky ." The prevalence of this view is further confirmed by a reference from the 13th century which states: </P> <P> According to the Geometers (or engineers) (muhandisīn), the earth is in constant circular motion, and what appears to be the motion of the heavens is actually due to the motion of the earth and not the stars . </P> <P> Early in the 11th century Alhazen wrote a scathing critique of Ptolemy's model in his Doubts on Ptolemy (c. 1028), which some have interpreted to imply he was criticizing Ptolemy's geocentrism, but most agree that he was actually criticizing the details of Ptolemy's model rather than his geocentrism . Abu Rayhan Biruni (b . 973) discussed the possibility of whether the Earth rotated about its own axis and around the Sun, but in his Masudic Canon, he set forth the principles that the Earth is at the center of the universe and that it has no motion of its own . He was aware that if the Earth rotated on its axis, this would be consistent with his astronomical parameters, but he considered it a problem of natural philosophy rather than mathematics . </P> <P> In the 12th century, some Islamic astronomers developed complete alternatives to the Ptolemaic system (although not heliocentric), such as Nur ad - Din al - Bitruji, who considered the Ptolemaic model as mathematical, and not physical . Al - Bitruji's alternative system spread through most of Europe in the 13th century, with debates and refutations of his ideas continued up to the 16th century . </P>

Who said the sun revolved around the earth