Corpus of Electronic Texts Edition
An Irish Astronomical Tract (Author: [unknown])

Caibidil 28

Concerning the spheres of the sun.


I declare that the sun has two spheres. The first in accordance with the very great sphere147, which moves westwards, and advances from the east to the west of the world. If the motion of that sphere did not check the sun, it would be six full months journeying from the west to the east of the world above the earth without setting. It would be an equal length of time moving from the east to the west of the world invisible, and thus half of the year would be one day and the other half night.

The second sphere of the sun, called "the eccentric sphere,"148 is like that of the moon. The motion of this sphere is from the west to the east of the world, and this sphere containing the sun within it is near the earth on one side, and distant from it on the other side. When the sun is near the earth149 in that sphere it parches the southern portion of the earth greatly, so that that land is uninhabitable; and when it is furthest from the earth in the same sphere, its heat does not reach the earth, and a corresponding portion of the northern part of the earth is uninhabitable150 from excessive cold.

Now I will make a figure to show how those two orbits of the sun are within each other.