The Size of the Sun
These disagreements both as to the distance of the sun as well as its size derive from the fact that (1) these men, otherwise great scholars, have been very much preoccupied (ERRATUM, read “torserint” for “forcerint”) with the apogees and perigees of the two luminaries, namely the moon and sun, when, as a matter of fact, these bodies, especially the sun, are always at approximately the same distance from the earth, as will be seen in Book V, Chapter 11. (2) Then the fact that they have found the diameters of the sun and moon, as well as the shadow of the earth, to vary so much in size at different times (for it has been discovered that the orbs of the stars, even though they remain at the same distance from the earth and the same height above the horizon, now appear smaller, now greater. For the darker the night is, the larger they seem, and when rain has fallen and the air has cleared, they seem smaller. The atmosphere itself, moreover, is not always of the same height, and thus, when it is higher, they seem greater and nearer but when it is lower, they seem smaller and more distant. This will be demonstrated in Book V, Chapter 10. (3) Finally it is of greatest importance how the measuring of these heavenly bodies is carried out and what instruments are used, for if the measuring is not uniform, a variety of answers always results.
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