The Seasons of the Moon

[The duration of summer and winter on the moon, and the climate zones of the lunar globe]

Est autem circulus aliquis inter polos intermedius, vicem gerens nostri aequatoris terrestris, quo etiam nomine indigetabitur, bifariam secans tam divisorem, quam medivolvanum in punctis oppositis, cui quaecunque loca subsunt, eorum verticem Sol quam proximc quotidic et praecisc quidem diebus duobus oppositis in anno transit in puncto meridiei. Ceteris, qui versus polos utrinque habitant, in meridie Sol declinat a vertice ^100.

The circle intermediate between the poles, in the place of the equator of our Earth, we will call by the same name. On two sides the divisor and the Medivolva intersect at opposite points. For everyone underneath, the Sun passes nearly overhead each day and exactly overhead at noon on two opposite days of the year. For all the rest, who live towards both poles, the Sun declines from the zenith at midday.

Habent in Levania et nonnullam vicissitudinem aestatis et hiemis, sed eam nec comparandam varietate cum nostra, nec ut nos semper iisdem in locis, eodem anni tempore. Fit enim decem annorum spatio, ut aestas illa migret ab una parte anni siderei in partem oppositam, eodem loco supposito; quippe circulo annorum 19 sidereorum seu dierum 235 versus polos vicies fit aestas totiesque hiems, sub aequatore quadragies ^101; suntque apud illos quotannis sex dies aestivi, reliqui hiemales, ut apud nos menses ^102.

On Levania they also have some summer and winter changes, but they are not to be compared with the variety of our own. Nor are they, as with us, in the same places at the same time of the year. For in the space of 10 years, at any given location, the summer changes from one part of the sidereal year to the opposite part. Therefore, in a 19 sidereal-year cycle, or 235 lunar days, summer occurs 20 times near the poles, and winter as often, but 40 times beneath the equator. So for them, six summer days, each alike our months, go by in every year, and the rest are winter.

Ea vicissitudo vix sentitur circa aequatorem, quia Sol non ultra 5° iis locis rursum prorsumque ad latera vagatur. Magis sentitur juxta polos, quae loca Solem alternis semestribus habent aut non habent, uti penes nos in Terris ii, qui sub alterutro polorum habitant.

These changes are hardly sensed near the equator, because there the Sun roams no more than 5 degrees back and forth on either side. It is much more evident near the poles, which alternately see the Sun, and see it not, for six months at a time, as it is for those of us on Earth who live beneath either of the poles.

Itaque etiam Levaniae globus in quinque zonas abit, terrestribus nostris quodammodo respondentes ; sed torrida vix habet 10 gradus, ut et frigidae; totum reliquum cedit temperatarum nostrarum analogis ^103. Et transit torrida per meditullia hemisphaeriorum, semissis scilicet longitudinis per subvolvanos, reliquus semissis per privolvas.

Accordingly, the globe of Levania, too, is divided into five zones, corresponding in certain ways to our terrestrial zones. But the Torrid Zone spans barely 10 degrees, as does the Frigid zone. All of the remainder falls under the analogues of our Temperate Zones. The Torrid Zone crosses through the middle of the hemipsheres with half its length through the Subvolva and the remaining half through the Privolva.

Ex sectionibus circulorum aequatoris et zodiaci existunt etiam quatuor puncta cardinalia, ut sunt apud nos aequinoctia et solstitia, et ab iis sectionibus initium est zodiaci circuli ^104. Sed valde velox est motus stellarura fixarura ab hoc initio in consequentia, quippe annis viginti tropicis, id est una aestate et una hieme definitis, totum zodiacum transeunt, quod fit apud nos vix annis 26000 ^105. Atque haec de motu primo.

From the intersections of the equatorial and zodiacal circles arise four cardinal points just like our equinoxes and solstices, and the zodiacal cycle commences at these intersections. But as a consequence of this, the movement of the fixed stars is very swift, since in 20 tropical years – which are defined as one summer and one winter – the entire zodiac passes by, which happens with us once in nearly 26000 years. So much for the first motion.

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