Universo

Since 1998, when Margherita Hack described our understanding of the structure of the universe in this entry published in *Frontiere della vita* by the Istituto della Enciclopedia Italiana, astronomy has certainly made great strides: some ideas that were still in their infancy have been developed, and new discoveries have opened up entirely new avenues of research, as Francesca Matteucci explains in the introduction to this volume. However, the analysis by the author—one of the world’s most renowned astrophysicists—remains a cornerstone in this field: for the way she reconstructs the processes leading to the formation of a star, its evolution, and then its death; for the way she outlines the general characteristics of our galaxy, other galaxies, and galaxy clusters, and reports observations indicating the presence of dark matter; and, finally, for how she illustrates the findings regarding the origin of the universe and its history.