which passed the meridian nearly at the same time, both at upper and lower culmination, and found no difference whatever; whereas he shows that there would have been a parallax at lower culmination equal to 5812′ if the star had been as near to us as the moon is.[1] Therefore the star could not be situated in the elementary region below the moon, nor could it be attached to any of the planetary spheres, as it would have been moved along with the sphere in question in a direction contrary to that of the daily revolution of the heavens, while his observations show that it has since its first appearance remained immovable. Consequently, it must belong to the eighth sphere, that of the fixed stars; and it cannot be a comet or other fiery meteor, as these are not generated in the heavens, but below the moon, in the upper regions of the air, upon which all philosophers agree, unless we are to believe Albumassar, who is credited with the statement that he had observed a comet farther off than the moon, in the sphere of Venus. Here again Tycho expresses the hope that he will some time get a chance of deciding this matter (as to the distance of comets); but anyhow, he adds, this star cannot have been a comet, as it had neither the appearance of one nor the proper motion which a comet would have been endowed with.
The third paragraph deals with the magnitude and colour of the star. The volume of a star is very considerable; the smallest are eighteen times as great as the earth, those of the first magnitude 105 times as great. Therefore the new star must have been of immense size. He then describes its gradual decline, until it "now, at the beginning of May, does not exceed the second magnitude." It must,
- ↑ He assumed that the parallax would be = 0 at the upper culmination, but in his later work he remarks that this is a mistake, and that it would be nearly 7′.
