light and space
Light is made up of little packets of electrical energy called photons. Light travels through space in waves but unlike sound it does need any matter to carry its energy along. This means light can travel through a vacuum. Nothing can travel faster than light energy and the speed of light is one of the most important numbers in physics. Light also comes in different frequencies from radio waves through to gamma rays. The amount of energy in a light wave is related to its frequency. High frequency light such as gamma rays have more energy than low frequency light such as radio waves. Because light travels in straight lines it can't travel around corners. It continues until it hits something and is either reflected, refracted or absorbed. Radiation from the sun travels through space until it hits the Earth. The radiation warms the molecules of our atmosphere and they warm other molecules. This heat transfer is called conduction.