Light pollution first gained attention when people realized they could no longer see the night sky as they once did due to excess visible and ultraviolet light from cities. However, in recent years, it has become clear that artificial night lighting worries not only astronomers. Studies have shown that artificial night lighting harms a variety of animals. To preserve the natural darkness of the sky in the world, parks of the dark (or starry) sky are created, which are the areas of a unique natural environment that protect the natural night darkness from pollution by artificial light. They are the equivalent of nature reserves - territories with exceptional natural value. They perform protective functions for the darkest corners of our planet, where the night environment is not disturbed by artificial light. These parks perform not only ecological but also educational functions. Darkness protection is slowly being incorporated into existing conservation areas such as national parks. Darkness is a natural resource that needs protection.

            In 2016, Transcarpathian Dark Sky Park was created. For its registration and entry into the International Association of Dark Sky Parks, the brightness of the night sky was measured in different places in this park to determine the state of light pollution in this area. The results of the measurements fully satisfied the requirements for dark sky parks. In all places of the Transcarpathian Dark Sky Park where we performed measurements, the average value of the background of the night sky was ~21.50 mag/arcsec². In 2021, an application for registration of Transcarpathian Dark Sky Park in the International Association of Dark Sky Parks was accepted. Research into the state of light pollution on the outskirts of the Dark Sky Park is also ongoing, namely at two optical observation stations - Uzhhorod and Derenivka. The results of changes in the background of the night sky in these places over a 40-year time interval are presented.

Keywords: night sky background, light pollution, dark sky parks, artificial light, astroclimate, astrotourism.