Brahe, Tycho (1546 - 1601)
Tycho Brahe (14 December 1546 – 24 October 1601), born Tyge Ottesen Brahe,was a Danish nobleman known for his accurate and comprehensiveastronomical and planetary observations. He was born in Scania, then part of Denmark, now part of modern-day Sweden. Tycho was well known in his lifetime as an astronomer and alchemist.
His work as an astronomer was remarkably accurate for his time. Most importantly, it had a most significant impact which remains today.
In his De nova stella (On the new star) of 1573, he refuted the Aristotelian belief in an unchanging celestial realm. His precise measurements indicated that "new stars" (novae or also now known as supernovae), in particular that of 1572, lacked the parallaxexpected in sub-lunar phenomena, and were therefore not "atmospheric" tail-less comets as previously believed, but occurred above the atmosphere and moon. Using similar measurements he showed that comets were also not atmospheric phenomena, as previously thought, and must pass through the supposed "immutable" celestial spheres.
Source: wikipedia, NASA