Just how big is the galaxy? Learners read information about the size of the Milky Way galaxy to better comprehend its size. Pupils develop an understanding of the number of stars in the galaxy by finding just how big a billion is and...

This page is a continuation of a tutorial about light reflection and refraction. It contains a diagram and suggestions on how to derive Snell's Law, which governs the refraction of light in a medium. For background to this derivation,...

A physics usenet listing of frequently asked questions relating to relativity, answered by a number of scientists. Administrivia and Reference, Speed of Light, Special Relativity, General Relativity and Cosmology, Black Holes. Loads of...

Kids learn about the science of light. Energy made of waves and particles called photons traveling at the top speed in the universe. What is refraction? The difference between transparent, translucent, and opaque.