Sometimes the magnetic field emerges from the lower regions and loops back
down into the Sun. These magnetic structures can be seen extending up into
the corona. As particles follow the path created by the magnetic field they
form dynamic loops and arches that are most readily visible with special
telescopes. These structures are known as solar prominences. Below is an
image of a solar prominence taken by the Soft X-ray Telescope
on the Yohkoh satellite currently orbiting the earth.
Particles from the corona also stream out along the magnetic field lines of
the Sun that extend into interstellar space. This "solar wind" transports
particles through space at 400 kilometers per second. When
the solar wind reaches the earth the magnetic field of the earth will
sometimes trap these electrons and protons and pull them into the earth's
atmosphere. Atoms in the earth's atmosphere interact with these high energy
particles by accepting energy from them and then releasing that energy in the
form of colored light. This display of light is known as the Aurora Borealis
when it occurs in the northern hemisphere.
The corona emits energy of many different wavelengths, from long wavelength
radio waves, to short wavelength X-rays. The short wavelength X-rays do not
make it through the earth's atmosphere so X-ray images of the corona must be
taken above our atmosphere from telescopes in space. Soft X-ray images of
the corona are taken by a telescope on the Yohkoh satellite mentioned above.
(X-rays come in a wide range of energies. Soft X-rays are at the lower
end of the energy range and the term hard X-rays is given to those at the
higher end.)
By viewing the Sun with many different instruments, each tuned to a particular
wavelength of the Sun's energy, scientists can use their "different eyes" to
help look for answers to the many questions that still surround our nearest
star.