Introductory Astronomical Writings of the Ancients

introduction to astrology, were inscribed upon the sphere. For the arctic circle defines those stars that are always visible. The summer tropical circle contains the turning, and is the limit of the sun’s transition toward the north. The equinoctial circle contains the equinoxes. The winter tropical circle is the end of the sun’s approach toward the south, and contains the winter turning. The antarctic circle defines those stars which are not visible. Having, therefore, defined principles and results for the introduction to astrology, they were reasonably inscribed upon the sphere.

Of the aforementioned five parallel circles, the arctic circle is held entirely above the earth; the summer tropical circle is cut into two unequal parts by the horizon. And the greater segment is held above the earth, while the lesser [is] below the earth. The summer tropical circle is not cut by the horizon in the same way for every region and city; rather, according to the variations of the climates, it happens that the excess of the segments becomes different. And for those dwelling further north than us, it happens that the summer [circle] is cut by the horizon into more unequal parts. And there is a limit—a certain region—in which the entire summer tropical circle becomes above the earth. For those dwelling further south than us