The supernovæ are singular objects, they are extremely brilliant (being able to reach the luminosity of a whole galaxy), and can be even observed in full day. They were in Chinese astrology indicator boards of significant events (wars, famines...). They allowed later Tycho Brahé and Johannes Képler to bring a bright proof against the system aristotelician of the eight spheres.
We will describe in the continuation the first observations of this phenomenon, then we will present how the supernovæ were classified according to their observational characteristics.