Tyge (Latinized as Tycho) Brahe was born on 14 December 1546 in Skane, then in Denmark, now in Sweden. He was the eldest son of Otto Brahe and Beatte Bille, both from families in the high nobility of Denmark. He was brought up by his paternal uncle Jorgen Brahe and became his heir. He attended the universities of Copenhagen and Leipzig, and then traveled through the German region, studying further at the universities of Wittenberg, Rostock, and Basel. During this period his interest in alchemy and astronomy was aroused, and he bought several astronomical instruments. In a duel with another student, in Wittenberg in 1566, Tycho lost part of his nose. For the rest of his life he wore a metal insert over the missing part. He returned to Denmark in 1570.
In 1572 Tycho observed the new star in Cassiopeia and published
a brief tract about it the following year. In 1574 he gave a
course of lectures on astronomy at the University of
Copenhagen. He was now convinced that the improvement of
astronomy hinged on accurate observations. After another tour
of Germany, where he visited astronomers, Tycho accepted an
offer from the King Frederick II to fund an observatory. He was
given the little island of Hven in the Sont near Copenhagen,
and there he built his observatory, Uraniburg, which became the
finest observatory in Europe.
Tycho Brahe with metal insert over nose
Tycho designed and built new instruments, calibrated them, and instituted nightly observations. He also ran his own printing press. The observatory was visited by many scholars, and Tycho trained a generation of young
Sextant
astronomers there in the art of observing. After a falling out with
King Christian IV, Tycho packed up his instruments and books in
1597 and left Denmark. After traveling several years, he settled
in Prague in 1599 as the Imperial Mathematician at the court of
Emperor Rudolph II. He died there in 1601. His instruments were
stored and eventually lost
Sextant
Tycho's major works include De Nova et Nullius Aevi Memoria
Prius Visa Stella ("On the New and Never Previously Seen Star)
(Copenhagen, 1573); De Mundi Aetherei Recentioribus Phaenomenis
("Concerning the New Phenomena in the Ethereal World)
(Uraniburg, 1588); Astronomiae Instauratae Mechanica
("Instruments for the Restored Astronomy") (Wandsbeck, 1598;
English tr. Copenhagen, 1946); Astronomiae Instauratae
Progymnasmata ("Introductory Exercises Toward a Restored
Astronomy") (Prague 1602). His observations were not published
during his lifetime. Johannes Kepler used them but they remained
the property of his heirs. Several copies in manuscript
circulated in Europe for many years, and a very faulty version
was printed in 1666. At Prague, Tycho hired Johannes Kepler as
an assistant to calculate planetary orbits from his
observations. Kepler published the Tabulae Rudolphina in
1627. Because of Tycho's accurate observations and Kepler's
elliptical astronomy, these tables were much more accurate than
any previous tables.
Mural Quadrant
Tycho Brahe's contributions to astronomy were enormous. He not
only designed and built instruments, he also calibrated them and
checked their accuracy periodically. He thus revolutionized
astronomical instrumentation. He also changed observational
practice profoundly. Whereas earlier astronomers had been content
to observe the positions of planets and the Moon at certain
important points of their orbits (e.g., opposition, quadrature,
station), Tycho and his cast of assistants observed these bodies
throughout their orbits. As a result, a number of orbital
anomalies never before noticed were made explicit by
Tycho. Without these complete series of observations of
unprecedented accuracy, Kepler could not have discovered that
planets move in elliptical orbits. Tycho was also the first
astronomer to make corrections for atmospheric refraction. In
general, whereas previous astronomers made observations accurate
to perhaps 15 arc minutes, those of Tycho were accurate to
perhaps 2 arc minutes, and it has been shown that his best
observations were accurate to about half an arc minute.
Tycho Brahe
Tycho's observations of the new star of 1572 and comet of 1577,
and his publications on these phenomena, were instrumental in
establishing the fact that these bodies were above the Moon and
that therefore the heavens were not immutable as Aristotle had
argued and philosophers still believed. The heavens were
changeable and therefore the Aristotelian division between the
heavenly and earthly regions came under attack (see, for
instance, Galileo's Dialogue) and was eventually
dropped. Further, if comets were in the heavens, they moved
through the heavens. Up to now it had been believed that planets
were carried on material spheres (spherical shells) that fit
tightly around each other. Tycho's observations showed that this
arrangement was impossible because comets moved through these
spheres. Celestial spheres faded out of existence between 1575
and 1625.
Tychonic Universe
If Tycho destroyed the dichotomy between the corrupt and ever
changing sublunary world and the perfect and immutable heavens,
then the new universe was clearly more hospitable for the
heliocentric planetary arrangement proposed by Nicholas
Copernicus in 1543. Was Tycho therefore a follower of
Copernicus? He was not. Tycho gave various reasons for not
accepting the heliocentric theory, but it appears that he could
not abandon Aristotelian physics which is predicated on an
absolute notion of place. Heavy bodies fall to their natural
place, the Earth, which is the center of the universe. If the
Earth were not the center of the universe, physics, as it was
then known, was utterly undermined. On the other hand, the
Copernican system had a number of advantages, some technical
(such as a better lunar theory and smaller epicycles), and
others more based on harmony (an obvious explanation of
retrograde planetary motion, a strict demonstration of the order
and heliocentric distances of the planets). Tycho developed a
system that combined the best of both worlds. He kept the Earth
in the center of the universe, so that he could retain
Aristotelian physics (the only physics available). The Moon and
Sun revolved about the Earth, and the shell of the fixed stars
was centered on the Earth. But Mercury, Venus, Mars, Jupiter,
and Saturn revolved about the Sun. He put the (circular) path of
the comet of 1577 between Venus and Mars. This Tychonic world
system became popular early in the seventeenth century among
those who felt forced to reject the Ptolemaic arrangement of the
planets (in which the Earth was the center of all motions) but
who, for various reasons, could not accept the Copernican
alternative.
opposition- The situation of two heavenly bodies when their longitudes or right ascensions differ by 180? The moon is in opposition to the sun when the earth is directly between them.quadrature- Those points or moments at which a half moon is visible. More generally, it is the situation of two heavenly bodies when their longitudes differ by 90?atmospheric refraction- The change in direction of a ray of light as it passes from space into the atmosphere. This causes celestial objects to appear to be in a location different from their actual ones.retrograde planetary motion- At times the planets appear to be moving opposite to their direction of rotation. This is caused by the effect of the rotation of the earth on our observations of the other planets.