Chandra Sketches: Highlights of Light

Narrator (April Hobart, CXC): Light comes in different forms. The light that we see with our eyes is just a fraction of all light. Light also encompasses wavelengths ranging from radio waves to gamma rays.

Nothing in the Universe can travel faster than light. In a vacuum, light travels at over 300,000 kilometers (186,000 miles) per second. This means light could circle the Earth 7.5 times in one second.

As light travels, its path can be bent when it goes from one medium to another (such as air to water). It can also be blocked (when a shadow occurs, for example), reflected (as with a mirror), or absorbed (like when a stone is heated by infrared light (waves) from the Sun.)

Humans have learned how to harness light and employ it in technologies ranging from medical devices (MRI/laser) to cell phones to giant telescopes.