2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/9726We estimate the contribution of galaxies to the cosmological density Omega_0 including also their extended dark halos. We find Omega_gal< 0.1, so implying that the matter in galaxies cannot by itself close the Universe but marginally could be baryonic. (latex file)two figures available upon request).4 pages, preprint SISSA, 24/94/AAstrophysicstext