Today we know, and this will be the subject of this article, that the universe is in continuous evolution, even revolution. This observation has been possible only quite recently. It was necessary to wait for the observations of distant galaxies, undertaken between 1930 and 1950 by Edwin P. Hubble, the astronomer who was the first to show that the universe as a whole is presently expanding. We know now also that the form of the constellations closest to us, such as the Great Bear, has been modified over the last millennia. Ancient astronomers, and with them the rest of humanity, imagined at that time that the universe was eternal and unchangeable. Astrophysicists today are convinced, in the large majority, that twenty billion years ago the universe went through a unique phase during which it was very hot and very dense. To this phenomenon they have given the name of the original or primordial explosion. As will be seen later, certain people believe that the universe will once again experience this great “heat”, which will be generated during future contractions. Others foresee an increasingly frozen and empty future for the universe. Between this glorious past and this uncertain future, the universe each day reveals more of its splendor thanks to the arrival of modern techniques of observation and the beginning of the conquest of space. The purpose of this article is to give a brief survey of the manner in which astronomers see the universe today; working from the position of man in the universe, his relation to it begins to be understood better.