Copernicus to the Big Bang -
Tycho Brahe

Tycho Brahe

Tycho Brahe's Instruments

  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 & Kepler: The Unlikely Partnership That Forever 
Changed Our Understanding of the Heavens
by Kitty Ferguson
Walker Books, March 2002
ISBN-13: 9780802713902
ISBN-10: 0802713904

  On his deathbed in 1601, the Danish nobleman and greatest
  naked-eye astronomer, Tycho Brahe, begged his young
  colleague, Johannes Kepler, "Let me not seem to have lived
  in vain." For more than thirty years-- mostly in his native
  Denmark and then in Prague under the patronage of the Holy
  Roman Emperor, Rudolph II-- Tycho had meticulously observed
  the movements of the planets and the positions of the stars.
  From these observations he developed his Tychonic system of
  the universe-- a highly original, if incorrect, scheme that
  attempted to reconcile the ancient belief that the Earth
  stood still with Nicolaus Copernicus's revolutionary
  rearrangement of the solar system some fifty years earlier.
  Tycho knew that Kepler, the brilliant young mathematician he
  had engaged to interpret his findings, believed in
  Copernicus's arrangement, in which all the planets circled
  the Sun; and he was afraid his system-- the product of a
  lifetime of effort to explain how the universe worked--
  would be abandoned.

  In point of fact, it was. From his study of Tycho's
  observations came Kepler's stunning three Laws of Planetary
  Motion-- ever since the cornerstone of cosmology and our
  understanding of the heavens. Yet, as Kitty Ferguson
  reveals, neither of these giant figures would have his
  reputation today without the other. The story of how their
  lives and talents were fatefully intertwined is one of the
  more memorable sagas in the long history of science.

  Set in a singularly turbulent and colorful era in European
  history, at the turning point when medieval gave way to
  modern, Tycho & Kepler is both a highly original dual
  biography and a masterful recreation of how science
  advances. From Tycho's fabulous Uraniborg Observatory on an
  island off the Danish coast to the court of the Holy Roman
  Emperor, Rudolph II; from the religious conflict of the
  Thirty Years' War that rocked all of Europe to Kepler's
  extraordinary leaps of understanding, Ferguson recounts a
  fascinating interplay of science and religion, politics and
  personality. Her insights recolor the established characters
  of Tycho and Kepler, and her book opens a rich window onto
  our place in the universe.