The area between the Sun and the planets, the interplanetary medium, is a turbulent area dominated by a constant stream of hot plasma that billows out from the Sun's corona. This hot plasma is called the solar wind.

The first indication that the Sun might be emitting a "wind" came in the seventeenth century from observations of comet tails. The tails were always seen to point away from the Sun, regardless of whether the comet was approaching the Sun or moving away from it.

Basic Characteristics

The solar wind is composed mostly of protons and electrons but also contains ions of almost every element in the periodic table. The temperature of the corona is so great that the Sun's gravity is unable to hold on to these accelerated and charged particles and they are ejected in a stream of coronal gases at speeds of about 400 kilometers...