We take it for granted that the universe changes. It began with the Big Bang, is still expanding; stars generate, die and are recycled. But until the sixteenth everyone believed – as the great Greek philosopher Aristotle had taught – that the heavens are eternal and unchanging.
Then in 1572, a new star appeared. That shouldn’t happen. It was all supposed to be eternal and unchanging, after all. Comets were just about OK, as they moved across the sky and disappeared again, so people assumed that they were actually in Earth’s atmosphere. But the new star stubbornly remained still and bright for many months, before eventually fading away.Fading away made it worse if anything – that was two changes. The new star astounded many people, not least Tycho Brahe, an astronomer in Denmark.
Tycho was a colourful character. Born Tyge in 1546, he was one of twin boys. (He changed his name later to sound more academic.) His twin died at birth, and Tycho later maintained that he had to do the work of both of them to make up for his brother’s death. When he was a year and half old, Tycho was kidnapped by his uncle, who subsequently brought him up. His parents don’t seem to have been fussed – they didn’t claim him back. He became interested in astronomy, probably after seeing a spectacular eclipse in 1560. His intellectual foster/kidnap mother Inge Oxe encouraged his interests in academic subjects and he went to university. He wasn’t a quiet student, and lost part of his nose in a sword fight with another Danish nobleman, possibly over a maths question. Warning: don’t take maths too seriously. Ever after, he wore a metal fake nose to cover the wound. (In his portrait, it looks as though he has covered it with powder to make it blend in.) His regular nose was made of brass, but he might have had silver and gold noses for special occasions.
Tycho was already an astronomer when he saw the new star. In fact, it was the opposite of a new star – it was an old star dying. It was a supernova – a star far, far away that was exploding, but he didn’t know that. The supernova eventually faded away and was not seen again until 1952 when the radio telescope at the Jodrell Bank Observatory revealed its remains.
Tycho proved by making measurements that the star must be far beyond the moon – up with the other stars. This was mind-blowing: it meant everything everyone believed about the stars being unchanging forever was wrong. In 1576, a comet appeared and he was able to demonstrate that comets, too, are further away than the moon. A double whammy for the unchanging-universe theory.
Tycho’s life continued to be interesting. He was given an entire island on which to build an observatory, and he ruled it like a small kingdom. A very small kingdom – the island was called Hven and it was in the river Sont, Copenhagen. His observatory, Uraniborg, was the finest in Europe and he used it to build up an astonishing set of data from very accurate astronomical observations. But it wasn’t all work. There was a lot of feasting and socialising, though it didn’t always end well. Tycho famously had a pet moose (elk). We know about the moose because he wrote in a letter of its death: it drank too much beer at a feast and fell down the stairs of a castle. The letter was to someone he had promised to led the moose to. Who would have thought there was a market in moose-lending in sixteenth-century Europe?
Among Brahe’s assistants was the young Johannes Kepler, who would later become an equally great astronomer. Kepler left an account of his boss’s death, which came after another unfortunate social occasion. He states that Brahe refused to leave a feast to urinate (it would be impolite) and developed a terrible bladder condition straight afterwards. He died an agonising death eleven days later in 1601. A suggestion that Kepler murdered Brahe in order to make use of his data was overturned in 2010 when scientists examining his body found no trace of the poison Kepler was said to have used against him – so he really did die from refusing to go to the bathroom.
(You will – eventually – be able to read more about Tycho Brahe in The Story of Astronomy, coming out in 2017.)