|
ADVENTURES
IN GEOSPACE
In addition to providing light and warmth, the Sun
blows a million tons of matter into space every second.  This
matter is in the form of hot electrified material -
mostly electrons and protons - in the fourth state
of matter called plasma. This steady stream of matter
called the solar wind travels
through space at an average speed of 400km/s ("900,000
miles/hr) with extremes from 300 km/s ("700,000
miles/hr) to 900km/s ("2 million miles/hr). Particularly
energetic events on the Sun - sunspots,
solar flares and coronal mass ejections (CME) - blast
more particles into space. A typical CME can carry
10 billion tons of matter into space.
This constant barrage of fast moving, charged particles
in the solar wind could be very dangerous to the Earth.
However, in the 1930's Chapman and Ferraro modeled
that the Earth's magnetic field provided a complete
barrier to the plasma coming from the Sun. In the picture
below, the solar wind (green), moving from left, is
deflected by the magnetosphere (blue).
The collision of the supersonically flowing solar wind
with the magnetic field of the Earth forms a bow shock
shown in red. The interaction of the shocked solar
wind and the Earth's magnetic field forms what is known
as the Magnetopause. The Magnetopause is the barrier
to the solar wind.
 Although
there is a barrier to the penetration of the solar
wind plasma, some of its electrical energy does penetrate
the Earth's magnetic shield. This is enough to generate
millions of amps of electric current in the upper atmosphere,
and can create occasional magnetic storms. Very energetic
events like Coronal Mass
Ejections can create spectacular auroras, damage
satellites, disrupt radios, burn out power transformers
and corrode pipelines. Obviously, the magnetosphere
is not an impermeable magnetic shield. In the 1960's
James Dungey provided a mechanism by which the solar
wind and its imbedded magnetic field couple to the
Earth's magnetosphere. This mechanism he called magnetic
reconnection. Recent satellite missions, many of which
flew under the International Solar Terrestrial Physics
Program (ISTP), have gathered data that have allowed
scientists to build upon Dungey's theories. The new
picture of the solar-terrestrial interactions is more
complex. Powerful new models have
been constructed. Four of the Solar Terrestrial Probes
(STP) missions,
Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics
(TIMED),
Magnetospheric Multiscale Mission (MMS),
Geospace Electrodynamics Connection (GEC)
and Magnetospheric Constellation (MagCON)
will gather important information about the dynamic
structure of the magnetosphere and its affect upon
the upper atmosphere of Earth. But first it is important
to know about Electricity, Magnetism, Electromagnetism.
+
Back to Sun & Earth Background | +
Top
|
