Imagine the most vibrant colors you have ever seen. Perhaps you have gazed at a clear blue sky or envisioned lush green grass. Maybe you have been captivated by a breathtaking sunrise or sunset.
If you have been pondering with us for some time, you are aware of the origin of the colors you perceive. They are produced by the interaction of light waves with various objects. However, did you know that there are certain light waves that cannot be detected by the average human eye?
It’s true! Typically, humans can only see light with wavelengths ranging from 380 to 700 nanometers (nm). All the colors of the rainbow, from red to violet, fall within this range. However, ultraviolet (UV) light has wavelengths shorter than 380 nm, making it invisible to the human eye.
Curious about the origin of the term “ultraviolet”? You may already be aware that violet light has the shortest wavelength among all visible colors. This means that it travels faster and possesses more energy than other colors of light. The prefix “ultra-” means “beyond.” As such, ultraviolet light waves move faster than violet ones. Therefore, “ultraviolet” indicates that this type of light is beyond violet, which is the fastest color we can perceive.
Just because humans cannot see UV light does not mean it has no impact on us. The majority of UV rays are absorbed by the Earth’s atmosphere. However, those that reach us can cause sunburn and other harm. This is why the ozone layer is crucial. Without it, more UV light would reach the Earth’s surface.
Is UV light invisible to everyone? Surprisingly, no. Individuals with a condition called aphakia can see UV light waves. Those with aphakia lack an eye lens, often due to surgery or genetics. The absence of this lens enables them to perceive light beyond the visible spectrum, but it also leads to blurry vision and farsightedness.
In addition, some animals have the ability to see UV light. Scientists have long known that bees possess this ability, and it is also present in many birds and reptiles. Until recently, experts believed that UV light was invisible to all mammals. However, a recent study discovered that most mammals likely can see these light waves, including dogs, cats, and reindeer. The lenses in their eyes allow UV light to pass through.
What about the other end of the spectrum of visible light? Red light has the longest wavelength that humans can typically perceive. Light with longer wavelengths than red is known as infrared. Scientists used to believe that no one could see infrared light. However, current experts believe that many humans can perceive it, especially if multiple infrared photons reach the eye simultaneously.
How do you think the world would appear different if you could see UV light? Would you perceive a deeper shade of violet? Perhaps it would introduce an entirely new color!
Give it a Try
Still curious about ultraviolet light? Seek an adult who can assist you in further exploration with the activities provided below.
- Have you ever wondered what UV light looks like to birds and bees? You can see a simulation of it here. Consider why being able to see UV light is beneficial for other animals. Why do you think humans lack this ability? Discuss these questions with a friend or family member.
- Take some time to explore the topic of eyes and how they function. How do humans perceive visual information? How do our eyes differ from those of other organisms? Write a letter or email summarizing what you’ve learned for a friend or family member.
- Imagine how your surroundings would appear if you could see UV light. Visualize how objects around you might look. Then, grab some art supplies and create a picture depicting your imagination of how something nearby could appear. Be imaginative! Don’t forget to showcase your artwork once it’s complete.
Sources of Wonder
- https://science.nasa.gov/ems/10_ultravioletwaves (accessed 04 Aug. 2020)
- https://www.pbs.org/wgbh/nova/article/power-lines-look-like-terrifying-bursts-of-light-to-animals/ (accessed 04 Aug. 2020)
- https://www.ceenta.com/news-blog/why-cant-i-see-infrared-or-ultraviolet-light (accessed 04 Aug. 2020)
- https://www.bbc.com/future/article/20150727-what-are-the-limits-of-human-vision (accessed 04 Aug. 2020)
- https://www.healthline.com/health/eye-health/aphakia (accessed 05 Aug. 2020)
Leave a Reply