The Solar Wind
The Sun makes itself known throughout much of
the Solar System by the influence the
solar wind of high-speed charged particles constantly blowing off the Sun.
Extension of the Corona
The solar wind may be viewed as an extension of the outer atmosphere of the Sun
(the corona) into interplanetary space. As we have noted earlier, it is thought that the solar wind escapes from
coronal holes, where the Sun's magnetic field lines do not close and thus don't trap charged particles.
Components of the Solar Wind
The solar wind contains roughly equal number of electrons and
protons, along with a few
heavier ions, and blows continously (with superposed bursts)
from the
surface of the Sun. At the Earth, the solar wind has an average velocity of about 400 km/s and the
corresponding density of particles is several per cubic centimeter. This is a
remarkable velocity: particles in the solar wind from the Sun's surface travel
at a speed that would allow them to go from Los Angeles to San Francisco in
less than 2 seconds!