The sun's solar wind plasma is a stream of charged particles ejected from the sun's upper atmosphere. The solar wind interacts with every planet in our solar system. It also defines the border between our solar system and interstellar space.

"The sun's million mile-per-hour solar wind inflates a protective bubble, or heliosphere, around the solar system. It influences how things work here on Earth and even out at the boundary of our solar system where it meets the galaxy," said Dave McComas, Ulysses' solar wind instrument principal investigator and senior executive director at the Southwest Research Institute in San Antonio, Texas. "Ulysses data indicate the solar wind's global pressure is the lowest we have seen since the beginning of the space age." (Source: NASA/JPL/CalTech Ulysses Home Page.)

The solar wind is nothing more than a stream of charged particles flowing outward from the Sun with an average velocity of about 400 km/sec. It is a natural consequence of the Sun being so hot - the corona gas has too much energy to be gravitationally bound to the Sun.
(Source: NASA/GSFC, Imagine the Universe - The Sun.)

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The Sun’s magnetic field and releases of plasma directly affect Earth and the rest of the solar system. Solar wind shapes the Earth’s magnetosphere and magnetic storms are illustrated here as approaching Earth. These storms, which occur frequently, can disrupt communications and navigational equipment, damage satellites, and even cause blackouts. The white lines represent the solar wind; the purple line is the bow shock line; and the blue lines surrounding the Earth represent its protective magnetosphere. The magnetic cloud of plasma can extend to 30 million miles wide by the time it reaches earth.  (View full-size image.) (Source: NASA/ESA/SOHO, the SOlar & Heliospheric Observatory, a project to study the Sun from its deep core to the outer corona and the solar wind.)