When a light ray slows down and changes direction as a result of passing through different mediums – such as water or air.

Snell's Law, Reflection, and Refraction

In order to follow the quickest path through a system, a ray changes direction as it travels from a medium of one refractive index to another...


What is a Rainbow?

When sunlight encounters a drop of water in the atmosphere it can produce a colorful rainbow because the amount that light rays are bent as they...


Why do the Stars Twinkle?

Stars are actually very large, but they are very far away so they look small. In fact, stars are so far away from Earth that we commonly refer to...



Aberrations are errors in an image that occur because of imperfections in the optical system. Another way of saying this is that aberrations result...



If you’ve ever seen a rainbow or a prism split what appears to be white light into its rainbow of color components, you’ve seen...