BİRİNCİ FEN · İKİNCİ BÂB · DÖRDÜNCÜ FASIL · İkinci Madde
Second Article
It describes the outer eccentric sphere (felek-i hâricü’l-merkez) [491] of the planet Jupiter with its forms and movements.
O Noble One! Know that astronomers have said: For the order of the movements of the planet Jupiter, there exists a second sphere, called the carrier sphere, within the Common Eccentric Sphere, which is situated at a distance of five and a half degrees from the center of the world’s center towards the western direction, encompassed by two outer, inclined surfaces parallel to each other, forming a spherical body. And the convex surface of this sphere touches the convex surface of the first sphere (felek-i evvel) at a point which they call the “western point.” And because that place is the furthest point relative to the center of the world, when Jupiter reaches that point, it becomes very far and high from the center of the earth. Similarly, the concave surface of this second sphere is tangent to the concave surface of the first sphere at a common point which they call the “eastern point.” For it is the place closest to the center of the world. When this planet descends to that point through the movement of the carrier sphere, it has descended and approached the nearest point to the earth’s center.
Now, with this explanation and determination, when the second sphere separates from the first sphere and transforms into the form mentioned; necessarily, two different spheres of varying thickness remain behind from the first sphere, one of which contains and encompasses (hâvî) the second sphere, while the other is encompassed (mahvî) along with the second sphere. The thin side of the encompassing sphere (küre-i hâvî) faces towards the western point; its thick side comes towards the eastern point. The thin and thick sides of the sphere that is encompassed by the other are contrary to what has been described above, namely the thin and thick sides of the encompassing sphere. And the completion of these two spheres occurs when their entry points on the carrier sphere are completed, so one is called the completer (mütemmim-i hâvî) of the encompassing sphere, and the other is called the completer (mütemim-i mahvî) of the sphere encompassed by the other.
Since every sphere has its own particular movement and it is certain that it completes its revolution rotating on its own specific axis (mihver) and poles, the inclined orbit of the planet Jupiter causes the Common Eccentric Sphere of the planet Mars to move westward to eastward with its own particular movement within its Common Eccentric Sphere, carrying the star along with it. In this way, the planet Jupiter remains in each sign for a year [492], completing its orbit around the Sun once every twelve years. Because Jupiter is further from the earth than the other planets below it and has a wider circle, its movement appears slower compared to the other planets beneath it.