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Vocabulary:
* light - energy that travels in a straight line
* reflection - the bouncing back of light
* refraction - the bending of light
* opaque - no light passes through
* transparent - all light passes through
* translucent - some light passes through
* magnify - appear larger
* illuminate - to light up
* speed of light - light travels at 300,000km per second
Light is a kind of energy
But why does light make this journey at all? As you probably know, the Sun is a nuclear fireball spewing energy in all directions. The light that we see it simply the one part of the energy that the Sun makes that our eyes can detect. When light travels between two places (from the Sun to the Earth or from a flashlight to the sidewalk in front of you on a dark night), energy makes a journey between those two points. The energy travels in the form of waves (similar to the waves on the sea but about 100 million times smaller)—a vibrating pattern of electricity and magnetism that we call electromagnetic energy. If our eyes could see electricity and magnetism, we might see each ray of light as a wave of electricity vibrating in one direction and a wave of magnetism vibrating at right angles to it. These two waves would travel in step and at the speed of light.