Between the Sun and Earth - Solar wind
A constant stream of particles flies from the sun, with a temperature of about a million degrees. They fly with a velocity of about 450 kilometers per second, and this solar wind reaches out to at least the distance of the Voyager 2 space probe, and that is beyond Pluto's orbit at about 5914 million kilometers.
The origin of the solar wind lies in the Sun's corona. The solar wind
blows gas and dust oozing out of a cometary nucleus backward, creating the
characteristic `tails' of comets. This can be seen on the picture to the left.
(Click for a larger version).
To study the solar wind, the European space probe Ulysses has been
launced. Due to its unique orbit, it can for the first time study the
north and south polar regions of the Sun. It has shown that the solar wind is
very irregular, and much faster near the polar regions of the sun than
at equatorial latitudes.
