The practice of preventive conservation of cultural heritage consists of “all measures and actions aimed at avoiding and minimizing future deterioration or loss” of it (ICOM-CC, 2008). Unlike conservation treatments, preventive conservation deals with entire collections and their surrounding environment. It is known that exposing historical objects to the environment has a significant impact on their degradation process. Studying and managing risk factors is an indispensable practice within the management policies of any cultural institution. The National Institute for Astrophysics (INAF) holds some valuable historical collections, heritage derived from the Italian contribution to astronomy over the centuries. The management and protection of these collections faces many challenges. A preventive conservation plan, aimed at assessing and managing risks that threaten the collections, may offer many long-term benefits, allowing us to use available resources in the best possible way. In the past few years INAF-Astronomical Observatory “G.S.Vaiana” of Palermo has been working on the development of preventive conservation projects for its archival, bibliographic and scientific heritage. The present contribution reports on these ongoing experiences and intends to stimulate a discussion within the scientific community in order to individuate the problems we are called to respond to in Astronomical Observatories.

A night-sky luminance survey was carried on in Beijing to assess the level of light pollution. The luminance of the zenith night sky and skies in four directions at six sites with different distances from the city center was measured by using a photometric luminance meter. The Xinglong Station of National Astronomical Observatory was included to study the impacts of city lights on an astronomical observatory. The survey shows that the night-sky luminance decreases with increasing distance from the city center. Measurement results indicate that outdoor lighting in the Xinglong county town which is close to the observatory has non-negligible influence on the night sky at Xinglong Station.