Note 664 — SECOND PART. The Astronomy of Dante. (continued 4)
Reading edition
Rabbi Abraham ben Chija, in his Sphæra Mundi, written about 1100 a.d., says that Earth’s shadow extends as far as the distance of Mercury, not of Venus (Delambre, Histoire de l’astronomie ancienne, and Dreyer, Planetary Systems); but this does not agree with the figures given by Alfraganus.