09-08-2008 Great astronomers: Tycho Brahe. (Article 149)

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Simon Kenny
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09-08-2008 Great astronomers: Tycho Brahe. (Article 149)

Post by Simon Kenny » Tue Dec 30, 2008 9:27 pm

Great astronomers: Tycho Brahe. (Article 149)

Tycho Brahe and Johannes Kepler are mainly responsible for the great advances in astronomy in the late sixteenth century. From their observations and discoveries came the basic model of the Solar System we have to this day, with the Sun at its centre and planets, including Earth, rotating at various speeds around it. The observational genius of Tycho, who charted the night sky in unprecedented detail and the mathematical genius of Kepler, who worked with Tycho, led to a new understanding of orbital motion and the structure of planetary systems.

Tycho Brahe was born to a noble family in Southern Sweden in 1546. Always interested in astronomy, he realised that understanding the universe required careful observations recorded over long periods of time. He built an observatory on an island between Denmark and Sweden and filled it with equipment built to his own designs. One of his famous discoveries was the ‘Stella Nova’, or ‘new star’ that suddenly appeared in 1572 in the constellation Cassiopeia. It led him to question the long held belief that the stars were fixed in space forever. This new star was clearly changing- it appeared from nowhere and slowly disappeared over the next two years. It is now known as ‘Tycho’s Nova’, SN 1572, located about 7500 light-years from Earth.

Tycho had great respect for traditional religious thought on the structure of the universe. In his day, the Earth was considered the centre of the universe, in accordance with biblical teaching. Phrases like this: “You have made the world firm, unshakable” (Psalms 93:1 and 96:10) still had a powerful influence on the emerging scientific method of inquiry. In Tycho’s lifetime, there were two competing models of the universe: the traditional earth-centred model of Ptolemy, and the new sun-centred Copernican model. Tycho devised a compromise model to combine the two and reconcile religious belief with current scientific observations. In his system, the Sun orbits the Earth and the other planets orbit the Sun. This model, known as the ‘Tychonic System’, was for a while more popular than the more accurate sun-centred model devised by Copernicus.

Tycho was fortunate to have been funded by the kings of Denmark and other European royalty. Their interest in his work was not for scientific discovery, but for reading their futures through his astrological charts. Tycho made a serious study of the influence of the stars on human events and tried to give it a proper scientific foundation. However, his greatest contribution to astronomy is his careful observations of the changing skies over many years, which led directly to Kepler’s Laws that are the foundation of modern astronomy. Remarkably, he achieved all this before the age of the telescope!

Tycho is appropriately remembered on the Moon’s surface, by a large crater bearing his name. During the full Moon, crater Tycho can be seen to the South as a bright circle with rays radiating from it in all directions like spokes of a wheel.

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