Tycho

Tycho Brahe (1546-1601), a Danish nobleman, was one of the greatest astronomers of all time. Before Tycho’s time only Hipparchus was better. Tycho tried to prove Copernicus wrong but his work, continued by Kepler after his death, only proved Copernicus right once and for all.

Copernicus said that the planets went round the sun. Ptolemy said they went round the earth. Tycho said something in between: yes, the planets went round the sun, but the sun went round the earth!

Tycho turned to astronomy when he saw an eclipse while at university. He once got in a fight there in the middle of the night over a point of mathematics. He lost his nose and later got a metal nose made to put in its place.

Although he was a nobleman who was often full of himself, he did fall in love with a simple country girl and married her.

In the universities they taught Aristotle: the earth was the centre of the world, a place of endless change, but the heavens above the moon were perfect and unchanging. What about comets? Aristotle said they were below the moon, part of the earth’s weather.

Tycho proved the heavens were anything but unchanging. He became famous when he found a new star that was not there before. It was called Tycho’s star (we call it a nova). It soon became brightest star in the sky.

Tycho also proved that comets were not part of the weather but farther than the moon. By gathering observations from different parts of Europe he could tell that its position in the sky against the stars changed less than the moon’s, meaning it was farther away.

The king built an observatory for Tycho on the island of Ven in between Denmark and Sweden. There Tycho studied the stars with the best instruments in the world. He carefully recorded the motion of the sun and the planets. His measurements were five times better than anything ever made. He even took into account the effects of the air and the limits of his own instruments. He wanted to prove Copernicus wrong.

Tycho wrote a letter to Galileo and told him that if Copernicus were right, then we should be able to measure how far away the stars were. Galileo had no answer for that. What neither of them knew was how unimaginably far away the stars were.

When the king died Tycho had to leave the island. He travelled to Prague. There he met Kepler. Kepler knew what a gold mine Tycho’s tables of numbers were. He promised Tycho to continue his work after he died and prove Copernicus wrong once and for all.

Kepler did continue his work, but in the end he had to admit that Copernicus, with a few changes, was right after all.

Later in the 1600s Tycho’s old observatory was burned down by war. Riccioli, who named the craters of the moon, named the brightest one Tycho in his honour.

See also:

• Copernicus
• Aristotle
• Hipparchus
• Kepler
• Ptolemy
• Galileo