had certainly been no bright star visible when his attention had last been directed to that part of the heavens.  Such a phenomenon was so startling that he found it hard to trust the evidence of his senses.  He thought he must be the subject of some hallucination.  He therefore called to the servants who were accompanying him, and asked them whether they, too, could see a brilliant object in the direction in which he pointed.  They certainly could, and thus he became convinced that this marvellous object was no mere creation of the fancy, but a veritable celestial body—­a new star of surpassing splendour which had suddenly burst forth.  In these days of careful scrutiny of the heavens, we are accustomed to the occasional outbreak of new stars.  It is not, however, believed that any new star which has ever appeared has displayed the same phenomenal brilliance as was exhibited by the star of 1572.

This object has a value in astronomy far greater than it might at first appear.  It is true, in one sense, that Tycho discovered the new star, but it is equally true, in a different sense, that it was the new star which discovered Tycho.  Had it not been for this opportune apparition, it is quite possible that Tycho might have found a career in some direction less beneficial to science than that which he ultimately pursued.

[Plate:  The observatory of Uraniborg, island of Hven.]

When he reached his home on this memorable evening, Tycho immediately applied his great quadrant to the measurement of the place of the new star.  His observations were specially directed to the determination of the distance of the object.  He rightly conjectured that if it were very much nearer to us than the stars in its vicinity, the distance of the brilliant body might be determined in a short time by the apparent changes in its distance from the surrounding points.  It was speedily demonstrated that the new star could not be as near as the moon, by the simple fact that its apparent place, as compared with the stars in its neighbourhood, was not appreciably altered when it was observed below the pole, and again above the pole at an interval of twelve hours.  Such observations were possible, inasmuch as the star was bright enough to be seen in full daylight.  Tycho thus showed conclusively that the body was so remote that the diameter of the earth bore an insignificant ratio to the star’s distance.  His success in this respect is the more noteworthy when we find that many other observers, who studied the same object, came to the erroneous conclusion that the new star was quite as near as the moon, or even much nearer.  In fact, it may be said, that with regard to this object Tycho discovered everything which could possibly have been discovered in the days before telescopes were invented.  He not only proved that the star’s distance was too great for measurement, but he showed that it had no proper motion on the heavens.  He recorded the successive changes in its brightness from week to week, as well as the fluctuations in hue with which the alterations in lustre were accompanied.