International Day of Light

(Also known as IDL)

International Day of Light is observed next on Tuesday, May 16th, 2023 (101 days from today).

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International Day of Light on May 16th raises awareness for the appreciation of light and the role it plays in science, art, education, and sustainable development.

Imagine one day you think about how we can make a difference in science, culture, the arts, education and sustainability. There is a day to explore in the fields of medicine, media and energy and aim to unite them in search of a better world. May 16th is that day, recognized by UNESCO as the International Day of Light. As light is a key tool that enables innovation and technology creation in medical devices, high-speed Internet, energy-efficient lighting, high-sensitivity sensors, online data storage, conservation of cultural property, renewable energy… and much more.

History of International Day of Light

Although everyone knows what light is, it is difficult to define. Light is not just the opposite of darkness. It is electromagnetic radiation in the electromagnetic spectrum that is perceived by the human eye. Wavelengths of light that are visible are between 400 and 700 nanometers. Another way to define light is as a stream of photons traveling with wave-like properties at the speed of light.

While we perceive the world in many ways, light is one of the most important ways for us to understand the world around us. In addition, light energy comes in many forms including visible light, infrared waves, ultraviolet rays, gamma rays, and radio waves. According to Audrey Azoulay, director general of UNESCO, understanding light allows us to make the greatest advances in science and technology.

These are just a few of the many applications that light is used for:

  • Lamps are used to illuminate spaces, such as homes and offices.
  • UV lamps are used in phototherapy to treat certain diseases.
  • UV energy is used to kill bacteria and viruses from the air and water.
  • Light is used in fiber optic networks, helping to transmit information.
  • Lighting is essential for safety, such as vehicle headlights and traffic lights.
  • They are used in many household appliances, such as television sets, microwave ovens, and cell phones.
  • Natural light helps plants grow and brings many benefits to human health.
  • It seems like every part of our lives is affected by light in some way.

Because of the success of the International Year of Light and Light-Based Technologies 2015, UNESCO decided to organize a day dedicated to light. The first official International Day of Light was celebrated on May 16th, 2018. May 16th marks the anniversary of the laser's first successful operation. American physicist and engineer, Theodore Maiman is credited with inventing the laser. The first laser was appeared and fired since 1960.

International Day of Light is a global initiative that provides a platform for continued appreciation of light and its role in science, culture and the arts, education and sustainable development as well. as in fields as diverse as medicine, media and energy. The broad theme of light will enable diverse segments of society around the world to participate in activities that demonstrate how science, technology, art and culture can help achieve UNESCO's goals including education, equality and peace.

After a wildly successful International Year of Light, highlighting the importance of light-based science and technology and seeing more than 13,168 activities carried out in 147 countries, the Executive Committee of UNESCO, at its 200th session, established the International Day of Light May 16 every year (200 EX / QD 27). The 39th Congress adopted this decision in text 39 C/40.

The International Day of Light will be an annual celebration, providing a platform to continue to appreciate the central role light science and technology play in the lives of citizens from around the world. It will also provide a long-term follow-up of the achievements of the International Year of Light by raising the profile of science and technology globally and highlighting its applications in promoting education, improving improve quality of life worldwide and achieve the Sustainable Development Goals set forth in the United Nations 2030 Agenda for Sustainable Development.

The International Day of Light will help build new bridges between the sciences, education and the arts, meet the critical need for interdisciplinary science, and improve dialogue between citizens, scientists, decision makers, industry leaders and NGOs.

The International Day of Light will encourage community-driven actions around the world in access to science and education. The International Day of Light will provide an opportunity for UNESCO to fulfill its mission of promoting international cooperation in the fields of basic science and STEM Education, and will contribute to achieving its goal of bringing science, technology and innovation accessible to life.

How to celebrate International Day of Light

Worldwide events to celebrate this day include a light festival featuring an entertaining optical show, a science lecture, and a photo contest. Participation:

  • Think about the ways you benefit from light and how it helps you in your daily life.
  • Do some light fun activities with your child, such as making a periscope or rainbow?
  • Watch a science video on light.
  • Share amazing photos of light via the social media. When you do, make sure to use the hashtag #InternationalDayOfLight or #IDL.


International Day of Light has been observed annually on May 16th.


Sunday, May 16th, 2021

Monday, May 16th, 2022

Tuesday, May 16th, 2023

Thursday, May 16th, 2024

Friday, May 16th, 2025

Also on Tuesday, May 16th, 2023

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