2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/6120Following the coincidence A x atomic year ~ Earth year (s), (A = Avogardo number, atomic year=a_B/alpha c, a_B=Bohr radius, alpha= fine structure constant, c=light velocity) and considering the "niche" for alpha, i.e. 180^{-1}<alpha<85^{-1}, the Ecosphere radius is calculated. Key words: Fine structure constant; Planet orbit radii.6 pagesAstrophysicstext