If you think light is easy to see, think again! The universe is filled with light, and most of it is invisible to us.

Light is a form of electromagnetic radiation that exists in a spectrum that moves in waves across space. These include microwaves, infrared radiation, X-rays- radio waves, ultraviolet radiation, and gamma waves. The waves we are able to see are called “visible light waves,” which fall between about 380 and 750 nanometers (between infrared and ultraviolet). 

We humans see visible light waves as “colors of the rainbow,” each with their very own wavelength. From longest to shortest, these include: red, orange, yellow, green, blue, and violet.

There are some types of light that animals can see that we can’t. For example, birds can see in ultraviolet light, which contains waves that are shorter than visible light but longer than x-rays. Snakes, as well as some insects and fish, can see infrared light, which humans cannot see but can feel in the form of heat.

Light is super important for so many reasons besides vision. Light is Earth’s energy source. Without light, plants wouldn’t be able to create energy through photosynthesis. Simply put, light is the substance of life on Earth, and without it, life would cease to exist. 

What is the International Day of Light?

International Day of Light is a global initiative that is “an annual focal point for the continued appreciation of light and the role it plays in science, culture and art, education, and sustainable development, and in fields as diverse as medicine, communications, and energy,” according to its website. 

Looking for a way to celebrate? Check out this list of events happening around the globe!

TryEngineering Tuesday: Photonics

What do light, lasers, and fiber optics all have in common? Photonics! Without a doubt, photonics is really cool! From smartphone applications and laser shows to solar power and biomedical advancements, photonics is making our world a better place. Check out IEEE TryEngineering Tuesday: Photonics today.