One of the Starlight Foundation “Astronomical Monitors and Guides” training courses took place at Sigüenza starting at June the 28th. The Medieval City of Sigüenza has become one of the main tourist destinations in Castilla la Mancha. It was declared a Historic-Artistic Site in 1964. This small city has beautiful small streets that take us to a medieval period. Sigüenza is located in a rural region of Spain with dark skies and the region will probably be declared Starlight Reserve.
ACTION researchers had the opportunity to teach about the impacts of Light Pollution and how to raise awareness about this problem. During the practical work the students learned how to measure the sky brightness at night using photometers.
Since we had 30 students (and some teachers) eager to collaborate, we proposed to map the entire city of Sigüenza using the StreetSpectra method. After the distribution of some diffraction gratings and hands on instructions, the students took observations with their smartphones all over the city as shown in the following map.
The results show that Sigüenza street lamps are mostly High Pressure Sodium (HPS) providing warm color to the medieval buildings and stone paved streets. Unfortunately, there are some streets with white Light Emitting Diode (LED) lights, some of them very blue. The good news is that there is also some warm amber LED lighting on some streets.
The nocturnal illumination of Sigüenza, that encourages a walk during the night, is threatened by a wild plan of ornamental lights at the main square and the Cathedral. Some citizens helped by researchers are fighting to reverse the excessive ornamental lighting. You can browse this opinion piece published in the local paper ‘La Plazuela’ with pictures of the problem.