Here's why:
* Pupil Shape: A cat's pupil is vertical, like a slit. This shape allows for more light to enter in low-light conditions, giving them excellent night vision.
* Light Intensity: In bright light, the pupil constricts to a tiny slit, almost appearing as a thin line. This limits the amount of light entering, protecting the eye from damage.
* Dilation: In low light, the pupil dilates, becoming wider and more oval-shaped. This allows maximum light to enter, enhancing their vision in the dark.
So, what appears to be a color change is actually just a change in the pupil's shape due to the amount of light present.
The actual color of a cat's eye (iris) is generally consistent and is determined by genetics.