The earth at the centre?

Tycho Brahe (1546–1601)
De nova stella
Frankfurt: Godefrid Tampachius, 1610

Tycho Brahe placed the Earth at the centre of his system, around which the sun orbited, but concluded that all the other bodies orbited the sun. Observation again upset this theory. The ‘Great Comet’ of 1577 appeared in the Earth’s atmosphere, observed and recorded by Brahe. How could a star suddenly burst forth in the unchanging heavens?

Adams.6.61.2, pp. 478–479

Tycho Brahe was an accomplished astronomer and instrument maker who, unlike Copernicus, made many celestial observations. Built over the years 1576-1580 he founded an astronomical observatory named Uraniborg, situated on the Danish (now Swedish) island of Hven in the northern reach of the Øresund that was to become the model for our modern era with its buildings constructed for the purpose and the installation of the most accurate instruments available.

All the Hven observations were made with the naked eyes of the Uraniborg observers as these were the decades before the invention of the telescope, the placing of two lenses at the correct separation to produce a magnified image. Tycho had a strong Protestant faith and this led him to discard the ideas of Copernicus, as he felt that God must have ordained that the Earth occupy the centre of the Solar System. He was the only significant proponent of the Tychonic planetary system he postulated, where all the planets except the Earth revolved about the Sun; the Earth was at the centre of the orbit of Sun. Though this arrangement may have served to bring contemporary observations and theory into some agreement it remained one of some complexity and unarguably failed the test of Ockham’s razor in comparison to the uncomplicated Copernican system.

In November 1572 Tycho observed the explosion of a star, the supernova of today’s cosmology, in the constellation Cassiopeia. He published in his account in his Astronomiæ instauratæ progymnasmata or Introduction to the new astronomy of 1588. The phenomenon demonstrated another flaw in the argument that the heavenly sphere above the Earth was perfect and unchanging as part of God’s creation.

Tycho became the Imperial Mathematician at the court of the Holy Roman Emperor in Prague. An early practitioner of the emerging method of empirical investigation, the basis of science, his central aim was to make his observations as precise as possible. As important in the history of science was that, due to his recognition of the other’s inestimable mathematical ability, he brought Johannes Kepler to Prague and employed him to analyse his planetary observations for a year before his death.

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