Mashallah postulated a ten-orb universe rather than the eight-orb model offered by Aristotle and the nine-orb model that was popular in his time. In all Mashallah's planetary model ascribes 26 orbs to the universe , which account for the relative positioning and motion of the seven planets. Of the ten orbs, the first seven contain the planets and the eighth contain the fixed stars. The ninth and tenth orbs were named by Mashallah the "Orb of Signs" and the "Great Orb", respectively. Both of these orbs are starless and move with the diurnal motion, but the tenth orb moves in the plane of the celestial equator while the ninth orb moves around poles that are inclined 24° with respect to the poles of the tenth orb. The ninth is also divided into twelve parts which are named after the zodiacal constellations that can be seen beneath them in the eighth orb. The eight and ninth orbs move around the same poles, but with different motion. The ninth orb moves with daily motion, so that the 12 signs are static with