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by Wal Thornhill
from
Holoscience Website
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25 December 2004
As NASA�s Cassini spacecraft approached Saturn
last July it found evidence that lightning on Saturn
is roughly one million times stronger than lightning on Earth.
"That�s just astonishing to me!\" said University of Iowa Space
Physicist Don Gurnett, who notes that some radio signals have
been linked to storm systems observed by the Cassini imaging
instrument.
Also, variations in
Saturn�s radio rotation rate came as a surprise. Based upon more
than one year of Cassini measurements, the rate is 10 hours
45 minutes and 45 seconds, plus or minus 36 seconds. That�s about
six minutes longer than the value recorded by the Voyager 1
and 2 flybys of Saturn in 1980-81.
Scientists use the rotation rate of radio emissions from the giant
gas planets such as Saturn and Jupiter to determine the rotation
rate of the planets themselves because the planets have no solid
surfaces and are covered by clouds that make direct visual
measurements impossible.
Gurnett suggests that the change in the radio rotation rate
is difficult to explain.
"Saturn is unique in
that its magnetic axis is almost exactly aligned with its
rotational axis. That means there is no rotationally induced
wobble in the magnetic field, so there must be some secondary
effect controlling the radio emission. We hope to nail that down
during the next four to eight years of the Cassini mission."
One possible scenario
was suggested nearly 20 years ago. Writing in the May 1985 issue of
"Geophysical Research Letters," Alex J. Dessler, a
senior research scientist at the Lunar and Planetary Laboratory,
University of Arizona, argued that the magnetic fields of gaseous
giant planets, such as Saturn and Jupiter, are more like that of the
sun than of the Earth. The sun�s magnetic field does not rotate as a
solid body. Instead, its rotation period varies with latitude.
Commenting earlier this year on the work of Gurnett and his
team, Dessler said,
"This finding is
very significant because it demonstrates that the idea of
a rigidly rotating magnetic field is wrong. Saturn�s
magnetic field has more in common with the Sun
than the Earth. The measurement can be interpreted
as showing that the part of Saturn�s magnetic
field that controls the radio emissions has moved to a higher
latitude during the last two decades."
Comment:
Dessler is right. Saturn is more like the
Sun than the Earth. And the idea of a rigidly
rotating magnetic field is wrong. The beliefs that limit our
understanding are that lightning is generated by the input of solar
heat energy into an atmosphere and that magnetic fields come from
deep within a star or planet. The latter belief requires that
magnetic fields rotate rigidly with the body. But experts admit that
we still do not understand how earthly lightning is generated or how
cosmic magnetic fields originate.
It seems obvious to propose that a stellar or a planetary magnetic
field is a combination of the field due to a rotating charged body
and the field due to moving electric currents impinging on that
body. The interplay between the two, together with the effects of
uneven and moving distribution of charge within the rotating body,
gives rise to the complex and changing fields that we observe. This
obvious suggestion never gained acceptance because to provide the
Earth�s magnetic field, for example, a current of one billion
amperes is required. That would imply a tremendously strong electric
field at the Earth�s surface, which does not exist. But the fallacy
in that argument lies in the use of an idealized electrostatic model
with the Earth moving in a perfect vacuum and a zero potential at
infinity. The Earth moves in plasma. The clear air electric
field of the Earth shows that the Earth is charged. The Earth�s
electric field is confined within the Earth�s plasma sheath (double
layer) at the magnetospheric boundary. The potential
difference between the solar plasma and the Earth is largely
confined to the plasma sheath. And certainly the solar plasma is not
at zero potential (however that is measured).
One of the best arguments in favor of external electric effects
is the surprisingly even distribution of the Sun�s magnetic field
lines from pole to pole. It is distinct from a simple dipole field,
where the field lines are more concentrated at the poles. Field
aligned currents tend to space themselves evenly over the surface of
an electrode. So the current flowing into the Sun�s photosphere
along magnetic field lines causes the solar magnetic field to be
evenly distributed. In other words, the galactic electric
current impinging on the Sun controls its magnetism. The
enigmatic sunspot cycle and magnetic reversals
are therefore strongly affected by the Sun�s galactic electrical
environment.
The behavior of sunspots comes from the way electric power is stored
in an equatorial plasmoid, or donut, encircling the Sun. Laboratory
experiments show that the energy stored in such a plasmoid may be
delivered discontinuously to the central body in electrical
discharges to high-latitudes. As the input power is increased the
discharges move to lower latitudes. On the Sun, those discharges
punch a hole through the global electrical storm we call the
photosphere to form dark sunspots. The simple fact that sunspots
are cool and dark, not hot and bright, demonstrates that
the Sun (and all stars) are not powered
internally. Nature knew how to make electric lights long
before us!
What does this mean for the observations of megalightning on
Saturn? Saturn is a body that participates in an
electrical discharge with its solar environment. And like the Sun,
Saturn stores electrical energy in an encircling plasmoid. In fact,
Saturn has two plasmoids. One is outside the rings, the other
inside the rings. Discharges to Saturn must cross the rings. The
Voyagers arrived at Saturn during solar
maximum and witnessed the effect of such "lightning" discharges.
Radial Birkeland currents moved material out of the ring plane
which then cast shadows on the bright rings to create 'mysterious'
dark spokes. Cassini reached Saturn
at solar minimum so a steady drift of charge is now shunting the
electrical energy across the rings. There is no lightning across the
rings. Cassini has seen no 'spokes'. However, as solar
activity increases we may expect to see the ring spokes return.
The last step in the planetary discharge is to Saturn�s ionosphere
and atmosphere � causing megalightning. Such powerful
lightning punches lower atmosphere matter upwards into the
stratosphere where it appears as great white spots and streaks, or
storms. That explains the apparent connection between the
Saturnian storms and radio signals from the megalightning.
Finally, we come to the
change in rotation rate of Saturn as measured by
Saturn�s kilometric radiation (SKR), which is
modulated at a rate tied to the rotation of the planet�s magnetic
field. See
www-pw.physics.uiowa.edu/space-audio/cassini/sat-rotation/sat-rotation-java.html.
It is assumed that the magnetic field is generated in the body of
Saturn and represents the planet�s true rotation rate.
However, it is known
that the SKR period is significantly longer than the
averaged period for atmospheric features. Just as the Sun is
driven fastest at the equator, so the Faraday motor effect
of the encircling plasmoid drives Saturn�s atmosphere faster at
the equator than at higher latitudes. This mechanism would also
account for the striking north-south symmetry of Saturn�s wind
systems. It seems that between the Voyagers� visits in November 1980
and August 1981, and Cassini�s arrival in July 2004, the electrical
energy input to Saturn�s Faraday motor has eased and the
motor slowed. Saturn�s fierce winds have decelerated
at all latitudes along with the rotation of the planet�s magnetic
field, to which the source of the SKR seems tied.
Saturn�s slowdown is apparent, not real.
It is interesting that the SKR was observed to
disappear in the 2 to 3 days following the Voyager 2
encounter. It correlated with the immersion of Saturn
in Jupiter�s magnetotail or plasma sheath. Saturn
had been temporarily unplugged from its electrical power source.
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