How do visible light waves travel

Here is a false-color image of Phoenix. How does it compare to the true-color and space shuttle images on this page? We often use visible light images to see clouds and to help predict the weather. We not only look at the Earth from space but we can also look at other planets from space. This is a visible light image of the planet Jupiter.

It is in false color - the colors were chosen to emphasize the cloud structure on this banded planet - Jupiter would not look like this to your eyes. When looked at this way, quantities of light can be counted, like beads on a string. Humans have evolved to sense a small part of the light spectrum. Our eyes contain cells known as rods and cones. Pigments in those cells can interact with certain wavelengths or photons of light. When this happens, they create signals that travel to the brain.

The brain interprets the signals from different wavelengths or photons as different colors. The longest visible wavelengths are around nanometers and appear red. The range of visible light ends around nanometers.

Those wavelengths appear violet. The whole rainbow of colors falls in between. Most of the light spectrum, however, falls outside that range. Bees, dogs and even a few people can see ultraviolet UV light. These are wavelengths a bit shorter than violet ones. Even those of us without UV vision can still respond to UV light, however. Our skin will redden or even burn when it encounters too much. Many things emit heat in the form of infrared light.

Mosquitoes and pythons can see in this range. Imagine holding one end of a piece of rope. If you shake it up and down, you create a wave, with the rope as your medium.

When your hand moves up, you create a high point, or crest. But the crests and troughs do move away from your hand as the wave travels along the rope. The same thing happens in other waves. If you jump in a puddle, your foot pushes on the water in one spot. This starts a small wave. The water that your foot hits moves outward, pushing on the water nearby. This movement creates empty space near your foot, pulling water back inwards.

The water oscillates, moving back and forth, creating crests and troughs. The wave then ripples across the puddle. The water that splashes at the edge is a different bit of water than where your foot made contact.

The energy from your jump moved across the puddle, but the matter the molecules of water only rocked back and forth. Light, or electromagnetic radiation, also can be described as a wave. The energy of light travels through a medium called an electromagnetic field. This field exists everywhere in the universe. It oscillates when energy disturbs it, just like the rope moves up and down as someone shakes it. They can cross empty space because their medium does not involve physical matter.

Scientists use several properties to measure and describe all these types of waves.