On the evening of Friday 22 September, CERN once again participated in “La nuit est belle!”. This initiative was launched four years ago by Greater Geneva, in collaboration with the Muséum d’histoire naturelle de Genève, the Société Astronomique de Genève and the Maison du Salève, and it aims to encourage municipalities in the area to switch off their public lighting for one night.

The three previous events explored themes of astronomy, nocturnal biodiversity and energy saving and this year the focus was on people and the night. Lighting has a significant impact on our bodies and habits, and “La nuit est belle!” provided an opportunity to reflect on two crucial issues: health and safety at night. On the one hand, excessive lighting around our homes can disrupt our circadian rhythm and lead to sleep disorders. On the other hand, switching off public lighting in the middle of the night raises safety concerns for people who are out and about, whether they are cyclists, pedestrians, persons with reduced mobility or persons with visual impairments.

This year, no fewer than 184 of the 209 municipalities that make up Greater Geneva participated in the event. Of these, 110 were in France, 29 were in the Nyon region and 45 were in the canton of Geneva. CERN also took part by turning off the lights at its sites – including the Globe, the Science Gateway, l'esplanade des Particules, gates A, B, C and E and the roads and carparks of the Meyrin and Prévessin sites, as well as the SPS and LHC sites – throughout the evening and the night.

Unfortunately, owing to adverse weather conditions, the stargazing event planned by the CERN Astronomy Club had to be cancelled. Nevertheless, CERN is proud to support this initiative to raise awareness about the importance of darkness for our wellbeing and environment.

For more information on this event, visit https://www.lanuitestbelle.org