Plasma

Plasma is superheated matter – so hot that the electrons are ripped away from the atoms, forming an ionised gas. It comprises over 99% of the visible universe. In the night sky, plasma glows in the form of stars. That branch of lightning that cracks the sky is plasma. So is the sun… and so are neon signs on city streets. Plasma is often called ‘the fourth state of matter’, along with solids, liquids and gas. Just as a liquid will boil, changing into a gas when energy is added, heating a gas will form a plasma – a soup of positively charged particles (ions) and negatively charged particles (electrons).