Solar phenomena move about and can travel at a few hundred meters per second when they first appear. The solar wind is a stream of plasma released from the Sun's upper atmosphere. It consists of mostly electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in density, temperature and speed over time and over solar longitude. These particles can escape the Sun's gravity because of their high energy. The solar wind is divided into the slow solar wind and the fast solar wind. The slow solar wind has a velocity of about , a temperature
Plasma (physics) first used the word "plasma" in analogy with blood. Mott-Smith recalls, in particular, that the transport of electrons from thermionic filaments reminded Langmuir of "the way blood plasma carries red and white corpuscles and germs." Langmuir described the plasma he observed as follows: Plasma is a state of matter in which an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behaviour of the matter. The plasma state can be contrasted with the other states: solid, liquid, and gas. Plasma is an electrically neutral medium of unbound positive and negative particles