... Tonight's Sky . ... Gravitational wave search provides insights into galaxy evolution and mergers . ... galaxies . ... Four spiral galaxies in Leo . ... Cosmologists 'see' the Cosmic Dawn . Through scientific calculations, scientists look back in time and hope to learn how galaxies like our own were made and understand more about dark matter. ... The Cosmic Dawn began as galaxies formed out of the debris of massive stars that died explosively shortly after the beginning of the universe. ...