A LOS CIELOS OSCUROS

Introduction
When we talk to friends or colleagues about dark and starry skies,
we almost automatically think of places far from urban centres that
are very distant and isolated. We are easily reminded of nights with
celestial views that amazed us, of star filled skies in deserts, forests or
beaches far from what we call civilization. Almost as if these forests,
deserts and seas were the only places in the world where so many
stars existed. . . . . .
Nothing could be further from reality: stars abound and shine
equally anywhere around our planet. Clearly, constellations change
with the seasons and between the Hemispheres, but the sky is
essentially the same for everyone. We see this during the day, in the
sunlight, but we literally lose sight of it at night when the greatest
contrasts between urban and isolated or uninhabited areas occur.
The lights that illuminate the cities we live in have a huge impact
on the skies. Effectively, street lighting, illuminated billboards, the
powerful lighting of sports stadiums and car lights, among other
light contaminants, emit a huge quantity of light into the sky.
This light is dispersed by atmospheric gas and dust, and generates a