than within the atmosphere of Earth. Craig tried to contradict Tycho by using his own observations of the comet, and by questioning his methodology. Tycho published an apologia (a defense) of his conclusions, in which he provided additional arguments, as well as condemning Craig's ideas in strong language for being incompetent. Another dispute concerned the mathematician Paul Wittich, who, after staying on Hven in 1580, taught Count Wilhelm of Kassel and his astronomer Christoph Rothmann to build copies of Tycho's instruments without permission from Tycho. In turn, Craig, who had studied with Wittich, accused Tycho of minimizing Wittich's role in developing some of the trigonometric methods used by Tycho. In his dealings with these disputes, Tycho made sure to leverage his support in the scientific community, by publishing and disseminating his own answers and arguments. Exile and later years When Frederick died in 1588, his son and heir Christian IV was only 11 years old. A regency council was appointed to rule for the young prince-elect until his coronation in 1596. The head of the council (Steward of the Realm) was Christoffer Valkendorff, who disliked Tycho after a conflict between them, and hence Tycho's influence at the Danish court steadily declined. Feeling that his legacy on Hven was in peril, he approached the Dowager Queen Sophie and asked her to affirm in writing her late husband's promise to endow Hven to Tycho's heirs. Nonetheless, he realized that the young king was more interested in war than in science, and was of no mind to keep his father's promise. King Christian IV followed a policy of curbing the power of the nobility by confiscating their estates to minimize their income bases, by accusing nobles of misusing their offices and of heresies against the Lutheran church. Tycho, who was known to sympathize with the Philippists (followers of Philip Melanchthon), was among the nobles who fell out of grace with the new king. The king's unfavorable disposition towards Tycho was likely also a result of efforts by several of his enemies at court to turn the king against him. Tycho's enemies included, in addition to Valkendorff, the king's doctor Peter Severinus, who also had personal gripes with Tycho, and several gnesio-Lutheran Bishops who suspected Tycho of heresy—a suspicion motivated by his known Philippist sympathies, his pursuits in medicine and alchemy (both of which he practiced without the church's approval) and his prohibiting the