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Early years

Tycho was born on 14 December 1546, at his family's ancestral seat at Knutstorp (Knudstrup borg; Knutstorps borg), about 8 kilometres (5.0 mi) north of Svalöv in then Danish Scania. He was the oldest of 12 siblings, 8 of whom lived to adulthood, including Steen Brahe and Sophia Brahe. His twin brother died before being baptized. Tycho later wrote an ode in Latin to his dead twin, which was printed in 1572 as his first published work. An epitaph, originally from Knutstorp, but now on a plaque near the church door, shows the whole family, including Tycho as a boy.

When he was only two years old Tycho was taken away to be raised by his uncle Jørgen Thygesen Brahe and his wife Inger Oxe, sister to Peder Oxe, Steward of the Realm, who were childless. It is unclear why Otte Brahe reached this arrangement with his brother, but Tycho was the only one of his siblings not to be raised by his mother at Knutstorp. Instead, Tycho was raised at Jørgen Brahe's estate at Tosterup and at Tranekær on the island of Langeland, and later at Næsbyhoved Castle near Odense, and later again at the Castle of Nykøbing on the island of Falster. Tycho later wrote that Jørgen Brahe "raised me and generously provided for me during his life until my eighteenth year; he always treated me as his own son and made me his heir".

From ages 6 to 12, Tycho attended Latin school, probably in Nykøbing. At age 12, on 19 April 1559, Tycho began studies at the University of Copenhagen. There, following his uncle's wishes, he studied law, but also studied a variety of other subjects and became interested in astronomy. At the university, Aristotle was a staple of scientific theory, and Tycho likely received a thorough training in Aristotelian physics and cosmology. He experienced the solar eclipse of 21 August 1560, and was greatly impressed by the fact that it had been predicted, although the prediction based on current observational data was a day off. He realized that more accurate observations would be the key to making more exact predictions. He purchased an ephemeris and books on astronomy, including Johannes de Sacrobosco 's De sphaera mundi, Petrus Apianus 's Cosmographia seu descriptio totius orbis and Regiomontanus 's De triangulis omnimodis.

Jørgen Thygesen Brahe, however, wanted Tycho to educate himself in order to become a civil servant, and sent him on a study tour of Europe in early 1562. 15-year old Tycho was given as mentor the 19-year-old Anders Sørensen Vedel, whom he eventually talked into allowing the pursuit of astronomy during the tour. Vedel and his pupil left Copenhagen in February 1562. On 24 March, they arrived in Leipzig, where they matriculated at the Lutheran Leipzig University. In 1563, he observed a close conjunction of the planets Jupiter and Saturn, and noticed that the Copernican and Ptolemaic tables used to predict the conjunction were inaccurate. This led him to realise that progress in astronomy required systematic, rigorous observation, night after night, using the most accurate instruments obtainable. He began maintaining detailed journals of all his astronomical observations. In this period, he combined the study of astronomy with astrology, laying down horoscopes for different famous personalities.

When Tycho and Vedel returned from Leipzig in 1565, Denmark was at war with Sweden, and as vice-admiral of the Danish fleet, Jørgen Brahe had become a national hero for having participated in the sinking of the Swedish warship Mars during the First battle of Öland (1564). Shortly after Tycho's arrival in Denmark, Jørgen Brahe was defeated in the action of 4 June 1565, and shortly afterwards died of a fever. Stories have it that he contracted pneumonia after a night of drinking with the Danish King Frederick II when the king fell into the water in a Copenhagen canal and Brahe jumped in after him. Brahe's possessions passed on to his wife Inger Oxe, who considered Tycho with special fondness.