The Visible Spectrum Is a Very Narrow Window
Visible means able to be seen. Human eyes detect a narrow band of wavelengths, and everything else is invisible to us.
Visible means capable of being seen. The visible spectrum is startlingly narrow: roughly 380 to 700 nanometres, a small slice of an electromagnetic spectrum running from radio waves metres long to gamma rays smaller than an atom. Most of what surrounds us is, quite literally, invisible.
- Able to be seen. *Clearly visible.*
- Noticeable or public. *A visible improvement.*
- Visibility — how far you can see. *Poor visibility.*
Word forms
| Form | Word | Example |
|---|---|---|
| Adjective | visible | Barely visible. |
| Adverb | visibly | Visibly shaken. |
| Noun | visibility | Reduced visibility. |
| Opposite | invisible | Invisible to radar. |
| Related | vision | Night vision. |
How it is used in a sentence
- The comet is visible to the naked eye.Astronomy.
- Visibility was down to fifty metres.Weather.
- She was visibly relieved.Adverb: in a way that could be seen.
The electromagnetic spectrum
- Radio — the longest wavelengths
- Microwave — used for cooking and communications
- Infrared — felt as heat
- Visible — the narrow band our eyes detect
- Ultraviolet, X-ray, gamma — increasingly short and energetic
From Latin *visibilis*, from *videre*, to see — the same verb behind *vision*, *evident*, *provide* and *survey*.
Why can we see only that band?
Because our eyes evolved under sunlight filtered by the atmosphere, which lets that range through most strongly.
Can other animals see beyond it?
Yes. Many insects see ultraviolet, and some snakes detect infrared with specialised organs rather than eyes.