Sorry, but your eye is gay.
A water droplet in the air acts as a prism. It bends light into its component colour wavelengths which your eye sees as a rainbow.
If it moves about then it is a floater. This happens when the jelly in the eye develops cracks. They often heal.
They just float around randomly, they have no resting place.
After a short visit at the opticians, they told me that it was called a 'floater'... Its when a bit of the jelly in your eye-ball comes loose and goes to the front of your eye, hence the black dot. It may be irritating, but there is nothing you can do about it. Your brain will adjust to it, but you just have to get used to it.
An Egg A floater that can sometimes be seen in the eye when looking into a blue sky. These were left over blood vessels that were helping to form your eyes before you were born.
There is no color your eye can see that is not in the rainbow.
There is no color your eye can see that is not in the rainbow.
Glaucoma
It is likely to be another floater but you should still get her eyes checked by an Optometrist- better to be safe than sorry.
Yes, water vapor can act like a prism. A rainbow is caused by raindrops, not by vapor. When light enters a raindrop at an angle to its surface, different colors refract at different angles as in a prism. A reflection occurs at the far side of the drop, and more refraction occurs as the light exits the drop, to be seen by your eye. Multiple reflections inside the drop are the cause of multiple ("double", even "triple") rainbows.
All colors visible to the human eye are in the rainbow. They have no specific meaning.
It is a little black speck inside your eyeball. It's usually blood or tissue that is floating around inside the jelly part of your eye. They're a normal part of aging.