The possession of this instrument was peculiarly fortunate for Tycho, for an event now occurred which roused him from his golden visions, and directed all his faculties into their earlier and purer current. On the 11th November 1572, when he was returning to supper from his laboratory, the clearness of the sky inspired him with the desire of completing some particular observations. On looking up to the starry firmament he was surprised to see an extraordinary light in the constellation of Cassiopeia, which was then above his head. He felt confident that he had never before observed such a star in that constellation, and distrusting the evidence of his own senses, he called out the servants and the peasants, and having received their testimony that it was a huge star such as they had never seen before, he was satisfied of the correctness of his own vision. Regarding it as a new and unusual phenomenon, he hastened to his observatory, adjusted his sextant, and measured its distances from the nearest stars in Cassiopeia. He noted also its form, its magnitude, its light, and its colour, and he waited with great anxiety for the next night that he might determine the important point whether it was a fixed star, or a body within, or near to, our own system.
For several years Tycho had been in the practice of calculating, at the beginning of each year, a sort of almanac for his own use, and in this he inserted all the observations which he had made on the new star, and the conclusions which he had drawn from them. Having gone to Copenhagen in the course of the ensuing spring, he shewed this manuscript to John Pratensis, a Professor, in whose house he was always hospitably received. Charles Danzeus, the French ambassador, and a person of great learning, having heard of Tycho’s arrival, invited himself to dine with him at the house of Pratensis. The conversation soon turned upon the new star, and Tycho found his companion very sceptical about its existence. Danzeus was particularly jocular on the subject, and attacked the Danes for their inattention to so important a science as astronomy. Tycho received this lecture in good temper, and with the anxious expectation that a clear sky would enable him to give a practical refutation of the attack which was made upon his country. The night turned out serene, and the whole party saw with astonishment the new star under the most favourable circumstances. Pratensis conceived that it was similar to the one observed by Hipparchus, and urged Tycho to publish the observations which he had made upon it. Tycho refused to accede to this request, on the pretext that his work was not sufficiently perfect; but the true reason, as he afterwards acknowledged, was, that he considered it would be a disgrace for a nobleman, either to study such subjects, or to communicate them to the public. This absurd notion was with some difficulty overcome, and through the earnest entreaties and assistance of Pratensis, his work on the new star was published in 1573.
This remarkable body presents to us one of the most interesting phenomena in astronomy. The date of its first appearance has not been exactly ascertained. Tycho saw it on the 11th November, but Cornelius Gemma had seen it on the 9th, Paul Hainzel saw it on the 7th of August at Augsburg, and Wolfgangus Schulerus observed it at Wittenberg on the 6th. Tycho conjectures that it was first seen on the 5th, and Hieronymus Munosius asserts that at Valentia, in Spain, it was not seen on the 2d, when he was shewing that part of the heavens to his pupils. This singular body continued to be seen during 16 months, and did not disappear till March 1574. In its appearance it was exactly like a star, having none of the distinctive marks of a comet. It twinkled strongly, and grew larger than Lyra or Sirius, or any other fixed star. It seemed to be somewhat larger than Jupiter, when he is nearest the earth, and rivalled Venus in her greatest brightness. In the first month of its appearance it was less than Jupiter; in the second it equalled him; in the third it surpassed him in splendour; in the fourth it was equal to Sirius; in the fifth to Lyra; in the sixth and seventh to stars of the second magnitude; in the eighth, ninth, and tenth, to stars of the third magnitude; in the eleventh, twelfth, and thirteenth, to stars of the fourth magnitude; in the fourteenth and fifteenth to stars of the fifth magnitude; and in the sixteenth month to stars of the sixth magnitude. After this it became so small that it at last disappeared. Its colour changed also with its size. At first it was white and bright; in the third month it began to become yellowish; in the fifth it became reddish like Aldebaran; and in the seventh and eighth it became bluish like Saturn; growing afterwards duller and duller. Its place in the heavens was invariable. Its longitude was in the 6th degree and 54th minute of Taurus; and its latitude 53° 45´ north. Its right ascension was 0° 26⅖´ and its declination 61° 46¾´. It had no parallax, and was unquestionably situated in the region of the fixed stars.
After Tycho had published his book, he proposed to travel into Germany and Italy, but he was seized with a fever, and he had no sooner recovered from it, than he became involved in a love affair, which frustrated all his schemes. Although Tycho was afraid of casting a stain upon his nobility by publishing his observations on the new star, yet he did not scruple to debase his lineage by marrying a peasant girl of the village of Knudstorp. This event took place in 1573, and in 1574 his wife gave birth to his daughter Magdalene. Tycho’s noble relations were deeply offended at this imprudent step; and so far did the mutual animosity of the parties extend, that the King himself was obliged to effect a reconciliation.
The fame of our author as an astronomer and mathematician was now so high, that several young Danish nobles requested him to deliver a course of lectures upon these interesting subjects. This application was seconded by Pratensis, Danzeus, and all his best friends; but their solicitations were vain. The King at last made the request in a way which ensured its being granted, and Tycho delivered a course of lectures, in which he not only gave a full view of the science of astronomy, but defended and explained all the reveries of astrology.
Having finished his lectures, and arranged his domestic affairs, he set out on his projected journey about the beginning of the spring of 1575, leaving behind him his wife and daughter, till he should fix upon a place of permanent residence. The first town which he visited was Hesse-Cassel, the residence of William, Landgrave of Hesse, whose patronage of astronomy, and whose skill in making celestial observations, have immortalized his name. Here Tycho spent eight or ten delightful days, during which the two astronomers were occupied one half of the day in scientific conversation, and the other half in astronomical observations; and he would have prolonged a visit which gave him so much pleasure, had not the death of one of the Landgrave’s daughters interrupted their labours. Passing through Frankfort, Tycho went into Switzerland; and, after visiting many cities on his way, he fixed upon Basle as a place of residence, not only from its centrical position, but from the salubrity of the air, and the cheapness of living. From Switzerland he went to Venice, and, in returning through Germany, he came to Ratisbon, at the time of the congress, which had been called together on the 1st of November, for the coronation of the Emperor Rudolph. On this occasion he met with several distinguished individuals, who were not only skilled in astronomy, but who were among its warmest patrons. From Ratisbon he passed to Saalfeld, and thence to Wittemburg, where he saw the parallactic instruments and the wooden quadrant which had been used by John Pratensis in determining the latitude of the city, and in measuring the altitudes of the new star.
Tycho was now impatient for home, and he lost no time in returning to Denmark, where events were awaiting him which frustrated all his schemes, by placing him in the most favourable situation for promoting his own happiness, and advancing the interests of astronomy.