One night in 1572, Danish astronomer Tycho Brahe saw what he thought was a brilliant new star in the constellation Cassiopeia. (We now know he was observing a supernova.) In 1604, a second supernova was observed. These discoveries caused scientists to seriously question Ptolemy's theory that all stars were contained in an outermost sphere of the universe that never changed.
Eina náttina í 1572 sá danski stjørnufrøðingurin, Tycho Brahe, tað, sum hann helt var ein nýggj glógvandi stjørna í stjørnumyndini Kassiopeia.(Vit vita nú, at hann eygleiddi eina sprongstjørnu.) Í 1604 varð sketta eftir eini aðrari sprongstjørnu. Hesar uppdagingar fingu náttúruvísindafólk í álvara at seta spurnartekin við ástøðið hjá Ptolemeus, at allar stjørnur funnust í uttasta himmallagnum í alheiminum, sum ogantíð broytist.