The travels of light
Light is sent out from a source from all directions. The energy in a light beam travels in a straight line at the speed of light (about 186,000 miles per second).
Light can be reflected, absorbed, or scattered. Most objects reflect light from their surface in all directions, no matter what direction the light started from. In most cases, only part of the light is reflected, while some is absorbed by the object.
The idea that light travels in straight lines conflicts with our everyday experience on Earth because we are surrounded by reflecting and scattering objects. Indoors, walls reflect light so that light produced by a source will have an effect on us from all directions. Outdoors, the daytime sky is not dark because impurities in the atmosphere scatter light. This makes it difficult to understand why, for example, the Moon glows so brightly in the nighttime sky, when it appears to be just a rocky ball in the daytime sky.
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