Abstract: The world at night offers a wealth of stimuli and opportunities as a resource for Optics education, at all age levels and from any (formal, non formal or informal) perspective. The starry sky and the urban nightscape provide a unique combination of pointlike sources with extremely different emission spectra and brightness levels on a generally darker, locally homogeneous background. This fact, combined with the particular characteristics of the human visual system under mesopic and scotopic conditions, provides a perfect setting for experiencing first-hand different optical phenomena of increasing levels of complexity: from the eye's point spread function to the luminance contrast threshold for source detection, from basic diffraction patterns to the intricate irradiance fluctuations due to atmospheric turbulence. Looking at the nightscape is also a perfect occasion to raise awareness on the increasing levels of light pollution associated to the misuse of public and private artificial light at night, to promote a sustainable use of lighting, and to take part in worldwide citizen science campaigns. Last but not least, night sky observing activities can be planned and developed following a very flexible schedule, allowing individual students to carry them out from home and sharing the results in the classroom as well as organizing social events and night star parties with the active engagement of families and groups of the local community. This contribution describes these possibilities and introduces some of the free resources available to put them in practice.

Abstract: Since the invention of electric lighting in the nineteenth century, the steadily increasing use of artificial light at night in outdoor spaces has grown to threaten the integrity of dark night skies and nocturnal terrestrial spaces. The conservation community has gradually come to accept the need to protect natural nighttime darkness, which finds expression in dark sky parks and similar protected areas. As these places begin to reap tangible economic benefits in the form of sustainable ‘astrotourism,’ the movement to actively protect them gains strength. The International Dark-Sky Association designates Dark Sky Parks and Reserves under a comparative ranking scheme that assigns night sky quality tiers according to a combination of objective and subjective characteristics, but shortcomings in the consistency of these ratings exist that undermine the consistency and reputation of the designation program. Here we consider potential changes to the qualification regime to make the ratings system more robust for the benefit of future designations.