This contribution describes an editorial project created in 2012 o enhance the cultural heritage of the Italian observatories: a regular column “Cieli di inchiostro” (Cosmic ink) devoted to valorize the astronomical historical archives and published in the “Giornale di astronomia”, the journal of Società Astronomica Italiana (Italian astronomical Society). In every issue of the journal a significant bygone fragment is presented and described. A letter, a diary page, a photograph, a map, a drawing etc... is pulled out from the archival folders to talk about its history. Not only science, instruments, discoveries and observations but also people, travels, public and private relationships, etc.. all the important scientific and human aspects an historical archives is able to offer. Furthermore the aim of this project is to raise awareness of activities of reordering, inventoring and valorization of the historical archives belonging to the National Institute for Astrophysics and the Department of Physics and Astronomy of the Bologna University. One more reason for this column is to invite historians, amateurs, students to search and use the documents kept in the archives of the observatories.