Tycho Brahe was the most meticulous astronomical observer of his time. Brahe, who lived between 1546 and 1601, set out to solve the day's most pressing astronomical problem: to determine whether the Earth or the Sun was at the center of the Solar System. To do this he and his assistants created the first major astronomical observatory where they devised and used the most accurate pre-telescopic astronomical instuments. Tycho Brahe thus compiled tables of precise measurements of the positions and brightnesses of planets and stars. Brahe never solved the Solar System problem himself - but left data so impressively accurate his assistant Johannes Kepler was able to develop definitive laws. Brahe is also remembered for witnessing a supernova in 1572, showing that the Great Comet of 1577 was not an atmospheric phenomena, and for his metal nose.

Tycho believed that the earth was fixed in the center of the world. Around the earth circulated the moon and the sun. Around the sun orbited the rest of the planets. He based this view mostly on measurements of the apparent movement of Mars, and he did not think it was explained by the traditional ptolemaic geocentric world system, where the earth was in the center and everything orbited around the earth.
Tycho Brahe was born three years after Copernicus had publishes his revolutionary work, "De Revolutionibus Orbium Coelestium", which put the sun in the center of the world, and all planets including the earth orbit around it. This is called a heliocentric world system. Tycho Brahe thought Copernicus was a brilliant astronomer, but he did not accept his world system, primarily for religious reasons. The church stipulated that the earth was the center of the universe.
Even if Tycho's world system was not widely accepted, it can be said to be important in such a way, that when Tycho Brahe tried to prove his world system by observations, he made a table of planetary movements. These tables were later completed and used by his assistant Kepler to make his famous planetary laws, which showed that Copernicus was right, the sun was the center and the planets moved around the sun. But the planetary movements were elliptical not circular, something which Kepler first thought was absurd, but he to had to accept it, since Tycho's accurate measurements confirmed this theory. Picture of the Tychonic World System, including the known planets of the time, with Saturnus being the furthest from the Sun. Inside the stars are the twelve signs of the zodiac.

During his time in Rostock he allegedly had a controversy with another student over who was the best mathematician. This resulted in a duel where he got a deep wound in his nose. The rest of his life he covered the scar with a plate probably made of a silver-copper alloy to imitate the colour of the skin.

``Consecrated to the all-good, great God and Posterity. Tycho Brahe, Son of Otto, who realized that Astronomy, the oldest and most distinguished of all sciences, had indeed been studied for a long time and to a great extent, but still had not obtained sufficient firmness or had been purified of errors, in order to reform it and raise it to perfection, invented and with incredible labour, industry, and expenditure constructed various exact instruments suitable for all kinds of observations of the celestial bodies, and placed them partly in the neighbouring castle of Uraniborg, which was built for the same purpose, partly in these subterranean rooms for a more constant and useful application, and recommending, hallowing, and consecrating this very rare and costly treasure to you, you glorious Posterity, who will live for ever and ever, he, who has both begun and finished everything on this island, after erecting this monument, beseeches and adjures you that in honour of the eternal God, creator of the wonderful clockwork of the heavens, and for the propagation of the divine science and for the celebrity of the fatherland, you will constantly preserve it and not let it decay with old age or any other injury or be removed to any other place or in any way be molested, if for no other reason, at any rate out of reverence to the creator's eye, which watches over the universe.

It is important to remember that Tycho Brahe lived before the invention of the telescope. Astronomical observation were made by the naked eye. Galilei invents the telescope 9 years after Tycho Brahe's death. The devices Tycho Brahe used and constructed are therefore mainly devices for measuring angles and positions. Also clocks were very limited at that time, the pendulum clock was not invented either, so to measure time, Tycho usually chose to use the movements of the stars and planets, with admirably accurate results.