Copernican Revolution Earth from the center of the universe, set the heavenly bodies in rotation around the Sun, and introduced Earth's daily rotation on its axis. While Copernicus's work sparked the "Copernican Revolution", it did not mark its end. In fact, Copernicus's own system had multiple shortcomings that would have to be amended by later astronomers. Tycho Brahe (1546–1601) was a Danish nobleman who was well known as an astronomer in his time. Further advancement in the understanding of the cosmos would require new, more accurate observations than those that Nicolaus Copernicus relied on and Tycho made great strides in this area.
Planetary nebula the French astronomer Antoine Darquier de Pellepoix described in his observations of the Ring Nebula, "...a very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". Whatever the true origin of the term, the label "planetary nebula" became ingrained in the terminology used by astronomers to categorize these types of nebulae, and is still used by astronomers today. Most planetary nebulae form at the end of the star's life, and are a relatively short-lived phenomenon, lasting perhaps a few tens of thousands of years, compared to a typical stellar lifetime spanning several billion years.