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A celebration of light, peace and the night sky

The International Day of Light (IDL) celebrates the ubiquitous role light has in our lives. From Argentina to South Africa, Japan and Pakistan, several events have taken place across all continents on May 16. The date is a token for people around the globe to connect with the importance of light in science, technology, cultural and social development.

In the Netherlands, Leiden University has been involved in several activities that celebrate light and its myriad uses. On the day itself, Leiden researchers explored the many uses of light for modern astronomy at 'Spectaculaire Spectra', an informal gathering at Brasserie het Park.

Not May 16 alone

The activities are not restricted to May 16 alone – they peak on that date, but take place the whole year. Later in September, 'Seeing Stars' will turn the city center lights off so that Leiden residents and visitors can look up and marvel at the night sky. 

'The idea of an international day was a natural one'

Even right now, the International Day of Light is on the agenda with exhibit 'SNAP! The night sky through a Leidener’s lens', open for visitation at the BplusC Stevenshof Library. 'The exhibition is developed to show Leiden residents and visitors that astronomy is closer and more approachable than they think. It gives them the opportunity to connect with fellow Leideners through science and art, and we're very proud of being a moving force behind it,' says Sanne van Gammeren, Education and Community Engagement Manager at Leiden Observatory.

A successful endeavour

The IDL builds on the momentum of the International Year of Light (IYL) in 2015, when over 13,000 activities took place across 147 countries and reached over 100 million people. 

'It was a truly exceptional scientific year for UNESCO and everybody else, that we wanted to keep that consortium together, so the idea of an international day was a natural one,' says Joe Niemela, senior scientist at the Abdus Salam International Centre for Theoretical Physics, Trieste (ICTP) and co-chair of the IDL 2022 steering committee. 

On its fifth edition in 2022, the IDL celebrated light as a metaphor for peace. 'From its several aspects to all areas of our lives, peace seems the most urgent right now – especially in the face of what is happening not only between Ukraine and Russia, but also in other parts of the world such as Syria, Yemen, Myanmar and so many other places,' Niemela adds.

Image: Baoli Gong | SPIE - IDL 2021 Photo Contest

The International Day of Light is administered from the International Basic Science Programme (IBSP) of UNESCO by a Steering Committee that includes representatives from a broad range of international partners. The communications node of IDL 2022 operates from the Astronomy and Society Group, Leiden University. For more information, visit lightday.org.

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