Magnetosphere is the magnetic
field that surrounds a layer of celestial bodies. In addition to the Earth;
Mercury, Jupiter, Saturn, Uranus and Neptune are also shrouded in the
magnetosphere. Earth is covered by a magnetosphere, as well as other magnetized
planets, Mercury, Jupiter, Saturn, Uranus and Neptune. Moon of Jupiter,
Ganymede, is also magnetized, but its strength is too weak to trap solar wind
plasma. Mars has a surface magnetization plotted.
The term
"magnetosphere" is also used to describe the region where the
magnetic field of celestial bodies dominated, example the pulsar magnetosphere.
Earth's magnetosphere is caused
by the Earth's core is not stable. Molecules in the Earth's core (which is
generally tangible ions) always move very quickly because of the temperature
and the influence of the gravitational field, causing an electric current that
creates a magnetic field, called the magnetosphere giant. Earth's magnetosphere was
discovered in 1958 by Explorer 1 satellite during a study conducted during the
International Geophysical Year. Previously, scientists knew that the electric
currents flowing in space, because solar eruptions sometimes cause disturbances
"magnetic storms". But no one knows where the stream flows and why,
or that the solar wind was there. In August and September 1958, Project Argus
conducted to test theories about the formation of radiation belts that may have
tactical common use in the war.
Here we will discuss the formation of the Van Allen belts and the natural phenomenon of the aurora borealis or the northern lights and aurora australis.
Van
Allen radiation consist of charged particles (most are electrons and protons)
which move around the Earth along donut-shaped paths (Figure a). These
radiation belts were discovered in 1958 by a team of researchers led by James
van Allen. They discovered these radiation belts after evaluating data that was
collected by the equipment onboard the Explorer I satellite.
The
charged particles trapped by the Earth’s non-uniform magnetic field circle the
Earth’s magnetic field lines from pole to pole along spiral paths. These
particles come mostly from the Sun and some from starts and other celestial
bodies. Therefore, these particles are called cosmic rays. Most of these
cosmic rays are diverted by the Earth’s magnetic field and never reach the
Earth. However, some of the cosmic rays escape and become trapped. The trapped
cosmic rays are the ones that from the van Allen belts. When these
charged particles are in the Earth’s atmosphere over the poles, they collide
frequently with other atoms, causing them to radiate visible light. Such
a process causes the formation of the
beautiful aurora borealis or the northern lights (Figure b). The same
phenomenon is seen on the Earth’s southern hemisphere, which is called the aurora
australis.
 |
| (a) The Van Allen belts
consist of changed particles (electrons and protons) that are trapped in the
Earth’s non-uniform magnetic field. Note that the magnetic field lines and the
donut-shaped paths of the particles. (b) Aurora borealis or the northern
lights, photographed near Fairbanks, Alaska. Aurora occur when cosmic rays
(electrically charged particles that come mainly from the Sun) are trapped in
the Earth’s atmosphere over the magnetic poles and collide with other atoms,
generating radiation of visible light. |