A LOS CIELOS OSCUROS

Prologue
The Consejo Nacional de Ciencia y Tecnología (CONACYT)
not only supports human resource training, research projects and
links with industry, but is also committed to the communication
of scientific research to the general public and the dissemination of
knowledge between specialists. Reaching society and a knowledge
economy cannot be achieved without the support of the community,
nor without science becoming a part of citizen culture. Participating
in thematic years is an excellent strategy to reach this goal of
popularizing science, especially if the topic is related to our daily life,
as is light.
The United Nations General Assembly proclaimed 2015 as
the International Year of Light and Light-based Technologies
(IYL 2015), with Mexico acting as one of the promoters of this
initiative. CONACYT took advantage of this decision to promote
the communication of science and technology on this subject and
supported various activities designed to promote awareness of light
and its applications. It may seem contradictory that, among the
many projects carried out during the IYL2015 that highlighted
the application of light across various disciplines, an international
meeting on The Right to Dark Skies was organized by the
UNESCO Office in Mexico. Light should be a common good, but
sometimes it is necessary to turn it off.
It is always a big surprise to children when they are taught that
white light contains all colours, by demonstrating its diffraction
through a prism. There is no museum of science in the world that
doesn’t have a disc, known as the Newton disc, with wedges of
colour that appears to be white when spun. That all colour comes
from something that is apparently colourless is one of the many
wonders of nature. This decomposition of colours that we see in
a rainbow was thought of as a serpent of light by our indigenous
populations. Light that comes from the Sun and marks the difference
between night and day is the basis of life on our planet. Another
great surprise is that not all light is visible to the human eye. The
electromagnetic spectrum also covers, among others, infrared and
ultraviolet regions that we cannot see, but whose effects are equally
important. Humans, who have always been curious, have studied
not only the light of our stars, but also seek to learn about all the
other objects in the universe that send us information in both visible
and invisible light form.