Since the celestial sphere appears to rotate counterclockwise around the North Star -- rising in the east, moving in an arc, then setting in the west -- it must mean that the earth is rotating from west to east.
(the celestial sphere; appears; ) (it; must mean; that the earth is rotating from west to east) Context(it must mean,List([153, 165))):(the earth; is rotating; from west to east)
it must mean,List([153, 165))
the celestial sphere it the earth
appears must mean is rotating
that the earth is rotating from west to east
from west to east