Dante and the early astronomers

by M. A. Orr

Now if a stone could be dropped from this pole of ours [the northern], it would fall far away yonder in the ocean just where, if a man were standing, he would always have the Pole Star exactly overhead. [“La stella”[383] is the Pole Star, [see p. 291]]. And I believe (Dante says) that from Rome to the north pole, in a direct line, is a distance of about 2,700 miles. To fix our ideas, let us imagine that at this spot there is a city called Maria, and let us imagine another city, called Lucia, at the spot exactly opposite, where a stone would fall if dropped from the other pole. And I believe that from Rome southwards to this second place would be a distance of about 7500 miles. Thus the distance between the two cities, in whatever direction the measuring cord be stretched, would be 10,200 miles, that is, half the circumference of the globe,[384] and the inhabitants of Maria would have their feet opposite the feet of those of Lucia. [If any two spots on a sphere are exactly antipodal, but in no other case, the distance may be measured in an infinity of directions, and always come out the same.]

Lastly, let us imagine a circle on the globe, which will be at equal distances everywhere from Maria and Lucia [the equator]. According to the opinions of the astrologers, if I understand them aright, and according to what is said by Albertus Magnus and by Lucan, this circle would divide the dry land from the ocean there in the south, approximately along the extremity of the First Climate, where amongst others live the Garamantes, who go almost always naked, to whom Cato went when fleeing from Cæsar.

“Approximately,” because the southern extremity of the First Climate, according to Alfraganus, lay a little north of the equator, although land extended, and was sparsely inhabited, as far the equator ([see p. 186]).

Dante speaks again of these extra-climatal races in De Mon. I. xiv. 43-51, where he contrasts the Scythians who live beyond the seventh climate, and therefore endure extreme inequality of days and nights, and suffer almost intolerable cold, with the Garamantes who live under the equator, where days and nights are always equal, and the heat is so intense that they can scarcely bear any clothing. Since “the astrologers who determine the climates”[385] had fixed their northern limit at 50½°, nearly the whole of Britain also lay, like barbarous Scythia, in this scarcely habitable region of long nights and bitter cold!

When we have marked these three places on the globe, i.e. the two poles and the equator, it is easy (Dante goes on) to see how the sun circles. I say then, that the heaven of the sun turns from west to east, not directly against the diurnal movement—that is, the movement which produces day and night—but obliquely against it, and so that its middle circle, which is similarly between its two poles, and on which is the body of the sun [i.e. the ecliptic], cuts in two opposite points the circle of the two first poles [the equator], that is, at the beginning of Aries and the beginning of Libra; it diverges from that circle in two arcs, one north and the other south. The highest points of these arcs are equally distant from the first circle in either direction, being 23 degrees and a little more; and the one summit is at the beginning of Cancer, and the other at the beginning of Capricorn.

Therefore, when the sun is in the beginning of Aries, travelling in the mid-circle of the first poles [the equator], Maria will see this sun circling the world, low down on the ground, or on the sea, like a mill-stone only half of which is seen, and day after day he will be seen to rise, like the screw of a press, until he has performed about ninety revolutions, or a little more. When these revolutions are accomplished, he will be as high in the sky above Maria as he stands in the sky of the Garamantes at middle-tierce at the time of equal days and nights.[386]

[From Conv. IV. xxiii. and III. vi., where Dante explains the use of temporal hours, we learn that mid-tierce on the day of the equinox is an hour and a half after sunrise, or 7.30 a.m. Since the sun moves through 360 degrees divided by 24, that is 15 degrees, in an hour, and his motion is vertical in equatorial countries at the equinox, it would bring him in 1½ hours to 22½ degrees above the horizon. His greatest height above the horizon at the pole is only one degree more than this, for it is obviously equal to the greatest distance between the equator and the ecliptic, i.e. 23½ degrees, since at the pole the equator coincides with the horizon. This gives a good idea, therefore, of the appearance of the sun in the sky to the people at Maria, and is a striking illustration of the difference between the polar sun and the equatorial. For at the time mentioned, the sun has only a quarter the height which it will attain at noon, when it will pass through the zenith of the Garamantes; yet this is the highest position in which the inhabitants of Maria can ever see it].

If a man stood upright in Maria, and kept turning his face to the sun, he would see it move to his right [as we do].

After reaching his greatest height in the sky, the sun would begin to descend again, in the same spiral way like a screw turning, for another ninety revolutions or so, until once more he was circling down on the horizon, only half his body visible.

Then he would be lost to sight altogether, and would begin to be seen in Lucia, where he would rise and descend in just the same way as in Maria. But if a man faced the sun in Lucia, he would see it moving to his left [as one does in Australia where it goes north at noon].