The Helix Nebula is an example of a planetary nebula. Though it looks like a bubble or eye from Earth's point of view, the Helix is actually a trillion-mile-long tunnel of glowing gases. In its center ...

To investigate the reflection of light by different types of surface, and the refraction of light by different substances. Remove the block. Join the crosses to show the paths of the light rays ...

It can only be seen by looking into the mirror. If a surface is rough, diffuse reflection happens. Instead of forming an image, the reflected light is scattered in all directions. This may cause a ...

Reflection can be a good thing ... They can get in the way of what you want to make pictures of. This usually happens with windows, where light bouncing off the glass can obscure your subject.

New observations with the Atacama Cosmology Telescope in Chile reveal the earliest-ever "baby pictures" of our universe, showing some of the oldest light we can possibly see.

Sahara dust colors the evening sky, glittering crystals shimmer in detail – This week, our gallery photographers once again show diversity.