What is a plasma?
Plasma is a 'fourth state of matter' in which many of the atoms or molecules are ionized. Plasmas have unique properties compared to the other states of matter i.e solids, liquids, and gases. Most plasmas can be thought of at first as extremely hot gases, but their properties are generally quite different.
Some examples of plasmas include the sun, fluorescent light bulbs and other gas-discharge tubes, very hot flames, much of interplanetary, interstellar, and intergalactic space, the earth's ionosphere and parts of the atmosphere around lightning discharges. Plasmas actually make up nearly 99 per cent of the matter in the universe but are extremely rare on Earth. One of the most spectacular examples of a plasma is the aurora. Known as the Aurora Australis or the Southern Lights this plasma forms as a result of interactions between the Earth's ionosphere and the solar wind.