De revolutionibus orbium coelestium divided into six "books" (sections or parts), following closely the layout of Ptolemy's "Almagest" which it updated and replaced: Copernicus argued that the universe comprised eight spheres. The outermost consisted of motionless, fixed stars, with the Sun motionless at the center. The known planets revolved about the Sun, each in its own sphere, in the order: Mercury, Venus, Earth, Mars, Jupiter, Saturn. The Moon, however, revolved in its sphere around the Earth. What appeared to be the daily revolution of the Sun and fixed stars around the Earth was actually the Earth's daily rotation on its own axis. Copernicus adhered
Planets of the Hainish Cycle current estimate. On the other hand, giant stars last 100 million years or so, which is much less time than Earth needed to evolve complex life. It is probable that the native humanoids are of Hainish origin, as are many other indigenous populations in the Hainish Cycle, descendents of genetically modified Hanish colonists from the ancient Hanish colonial epoch, similar to other planets in the cycle. This would account for the successful imbreeding, which should not be possible if they had evolved from completely different biospheres. In 1.5 million years, Eltanin will pass within 28 light years of Earth. At