Cats, dogs, and many nocturnal animals appear to have glowing eyes at night. This is because the back of their eyeballs include a special reflective layer. This helps animals (cats in this case) see better in low light by working like a mirror to reflect the light back through the eyes, giving them a second chance to absorb the light. These glowing colours are easier to see at night because the animal's pupils are wider.
Humans don't have this layer. That partially explains why when photos are taking using a flash, people's eyes have red spots in them. This is caused by the light from the flash traveling through the pupil and lighting up the blood-cell rich retina at the back of our eyes.
The secret behind so-called "red-eye-reducing cameras" is that they use two quick flashes instead of one. The theory being that the first flash will cause the subject's pupils to close up a little and let in less light, while the second will be used for the actual picture.
Humans don't have this layer. That partially explains why when photos are taking using a flash, people's eyes have red spots in them. This is caused by the light from the flash traveling through the pupil and lighting up the blood-cell rich retina at the back of our eyes.
The secret behind so-called "red-eye-reducing cameras" is that they use two quick flashes instead of one. The theory being that the first flash will cause the subject's pupils to close up a little and let in less light, while the second will be used for the actual picture.
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