The document discusses the Danish astronomer Tycho Brahe and his contributions to astronomy during the Renaissance period. It describes how Brahe dedicated his life to improving astronomy through careful observation and new inventions like the quadrant. Using his quadrant and other instruments, Brahe made extensive observations over 20 years from his own island observatory. His observations later helped Kepler discover his laws of planetary motion and Newton develop his law of gravity.

1. The renaissance, Tycho Brahe and the Quadrant
When the reformation ended in the 15th century in Denmark the renaissance began.
During the reformation in Denmark the Catholic Church owned most of the land, but that all
changed when King Frederik II and the nobility took over.
The historical time period was a reincarnation of the Antique world. Our ancestors went back
in time and used ancient knowledge to create a more modern world with focus on
individualism instead of God.
King Frederik II chose to spend a lot of money on the advancement of science.
The people became more intelligent and interested in exploring the universe. The world
picture as they knew it, began to be questioned, especially by one man, Tycho Brahe.
He was one of Frederik’s closest friends, and his discoveries helped shape modern science.
Tycho came from a noble family, and was fluent in Latin at the age of 12, where he also started
studying law at Copenhagen University. After experiencing a solar eclipse, Tycho became very
interested in astronomy. Tycho Brahe did not listen to his parents though, and chose to devote
his life to study the stars. But after spending a lot of time reading astronomy books and
looking at the sky, he discovered that a lot of the things written by earlier astronomers were
imprecise, or even wrong, and that he could only trust his own observations.
Tycho Brahe decided to dedicate his life to improve and renew astronomy. To do these
things, he created a string of new inventions to measure the stars in the sky and to calculate
their appearance in the future.
When he was 19 years old he got into an argument with a fellow nobleman, Manderup
Parsberg, about who the best mathematician was. Since they could not come to an agreement,
they had a duel. Unluckily for Tycho Brahe, he got his nose chopped off during the fight, and
had a replacement nose made for him, out of silver.
He studied alchemy and astrology until he was 22 years old, where he moved to Augsburg,
Germany, and worked for the mayor. Here Tycho invented a quadrant to measure the
positions of the stars in the sky.
In 1572 he discovered the, for him, biggest wonder in the world since the creation of life: He
saw with his own eyes a new star being “born” in the Cassiopeia constellation. Back then, they

2. were sure that God had created the world in six days, but now they could see that a new star
was born, and that the world was changeable, which was strongly in contrast to what they had
always believed.
Brahe wrote a book, “De nova stella”, about the new star, and became famous in Europe. At
this point he was only 26 years old.
Frederik the II offered Tycho Brahe his own island to observe the stars on, Ven, which is
located in Øresund, between Denmark and Sweden. Tycho accepted, and in 1576 he started
building his own stargazing castle, Uranienborg. After it was finished, Tycho found out that
the castle was not so great for stargazing, so he built an underground crypt, Stjerneborg,
where the things he invented would be stable and dry. He observed from Ven for 20 years,
during which he developed instruments, conducted extensive observations and calculation
programs, and showed his work in the form of scientific publications.
Tycho Brahe’s inventions included a celestial globe, upon which all the stars that he could see
were depicted. Sadly it burned in a fire many years later.
King Christian IV took over when Frederik II died in 1588. Tycho Brahe had been given
around 2% of Denmark’s income, both for research, but also to take care of the people of Ven
and other obligations. Brahe neglected to do this, though, and since Christian IV did not like
him, he stopped giving Tycho Brahe money. Tycho was not very happy about this, and moved
to Prague, where he met his scientific successor, Johannes Kepler from Germany.
Here he lived the last years of his life, finishing astronomical charts and preparing for his final
book, Astronomia insta-ura-tæ mechanica, which was published after his death. People are
suspicious as to whether Brahe died of natural reasons, or if he was poisoned by someone,
possibly Kepler, as Brahe had kept a lot of his observations secret, and many people wanted to
use them for their own work.
Brahe was one of the first astronomers to use his theories in practice. Most of the other
scientists only used theory.
Brahe’s instruments were still in use for high performance research even after his death.
Through his tireless stargazing on Ven through twenty years, he created an entirely new basis

3. for astronomy. Kepler later based his three laws on Brahe’s
observations, which helped Newton in discovering the law of gravity.
The Augsburg quadrant was Tycho Brahe’s largest and most precise
invention. The large quadrant was build to make measurements of the starry sky. It was built
with oak and iron. The quadrant had a radius of 5,43 m. Because of its size it was put 8-9
meters underground, and was close to 10 meters above ground. The quadrant needed
multiple people to control it.
At the time, the Augsburgs quadrant was the most precise instrument used to measure the
stars. Unfortunately, a storm broke the quadrant, and Brahe never rebuilt it because of its
large size.
When Brahe died, his successors inherited his sketches and theories. The most notable one
was Johannes Kepler.
Since the quadrant was so unstable and impractical, Brahe created a ring sphere. The ring
sphere was able to directly measure the coordinate differences in the system we still use, the
Equator system. It looks like the Ecliptic only celestial equator chosen as the basic great circle.
Brahe’s inventions was not only the best you could get in his time, but also today, as we
continue to use his ideas, and a few of his inventions, in astrology.

4. 3D-model