Solar wind

Solar wind is the plasma of charged particles (protons, electrons, and heavier ionized atoms) coming out of the Sun in all directions at very high speeds – an average of about 400 km/sec, almost a million mph! It is responsible for the anti-sunward tails of comets and the shape of the magnetic fields around the planets. Solar wind can also have a measurable effects on the flight paths of spacecraft.
The solar wind varies routinely through the 27-day rotation of the Sun, as well as sporadically, in response to violent eruptions in the corona. These eruptions can result in geomagnetic storms on Earth.
The composition of the solar wind reflects the composition of the solar corona, modified by solar wind processes. The exact mechanism of solar wind formation is not known. Accurately measuring its composition aids in separating the effects of these processes from the original makeup of the corona.