Waves that have wavelengths between about 0.4 millionths and ten billionths of a meter are known as visible light.

Here's why:

* Visible light is the portion of the electromagnetic spectrum that humans can see.

* 0.4 millionths of a meter is equivalent to 400 nanometers, which corresponds to the wavelength of violet light.

* Ten billionths of a meter is equivalent to 10 nanometers, which is in the range of ultraviolet radiation, but is still close to the visible spectrum.

So, the wavelengths you provided fall within the range of visible light, which is why we can see colors!