(continued)
X-Ray Flares
After the peak of the last eleven-year sunspot cycle in 1999, the sun has had a number of extremely large x-ray flare events. One of these, on April
2, 2001, was so large that it went off the scale completely. The previous scale ran to X-20 as the highest category, but this solar flare had to be
categorized as an X-22 event. The x-ray burst was not in the direction of Earth, but a much smaller x-ray flare in 1989 was responsible for knocking
out the whole Canadian power grid. If the X-22 event had hit Earth, possible consequences could have included major power outages, interruption of the
Internet, damage to telecommunications and GPS satellites, and even the wiping of computer hard drives. The most powerful flare observed since then
happened on November 4, 2003. It lasted eleven minutes and produced an x-ray flux of X-28.
The Carrington Event
These recent events, though very significant, are not actually the largest solar flares ever recorded. That honor goes to a flare that happened on
September 1, 1859. This has become known as the Carrington event after Richard Carrington, the young English astronomer who saw the event as it
happened from his private observatory.
It was a remarkable piece of luck that he happened to be observing the sun at the particular moment that the flare erupted, because the event lasted
for less than five minutes. In that time, a huge knot of sunspots appeared and generated a plume that was by far the biggest observed in the 160 years
records have been kept.
Before dawn on the following day, a huge firework display of auroral lights bathed Earth, reaching as far south as the Caribbean. The rainbow-hued
lights were so brilliant that it was said to be possible to read by them as if it were daylight. The Carrington event also caused major disruption to
the telegraph system worldwide.
Conventional astronomy suggests that a flare of this size may only happen once every 500 years or so, but even greater flares have been observed on
other stars. Some of these stellar megaflares have emitted quantities of radiation that would be likely to cause major loss of life on Earth.
The Maunder Minimum
Sunspot activity has been broadly increasing since the Maunder minimum period from 1645 to 1715, when there were very few sunspots. At a typical peak
of the sunspot cycle, there may be as many as 1,000 spots a year, but during the Maunder minimum the number of spots dropped as low as one or two a
year for a thirty-year period. This was also the peak of what has been called the Little Ice Age. This was a period of approximately 400 years, from
the fifteenth to the nineteenth centuries, when the drop in temperature was so great that the winter mortality rate in Europe increased dramatically.
In London, the river Thames froze over completely every winter. The edge of the Atlantic ice pack moved southward during the Maunder minimum and
glaciers started expanding.
The Maunder minimum was named after the astronomer Edward Maunder, who measured and photographed sunspots at the Greenwich Royal Observatory. It was
his studies of this unusual period in history that led to his discovery of the important eleven-year sunspot cycle.
Sunspot Cycles
The general increase in the sun's activity has been consistent for more than 100 years, but it seems to have reached a peak in sunspot cycle 22 from
1986 to 1996. Sunspot cycle 23 began in 1996 and ended in 2008. The cycle was six months late and weaker than normal.
Cycle 24 was due to start in March 2008, but it is more than a year late already. As of March 2009, there was still no sunspot activity whatsoever.
This is the longest period that the sun has been spotless for more than 100 years. Considering the maximum of this cycle is due in 2012, this might
seem to suggest that the peak of the cycle may again be less than the recent average. Yet, generally this cycle is still predicted to be 30-40 percent
more intense than the last one. The official prediction of the NOAA Space Weather Prediction Center is a peak of ninety sunspots in August 2012. There
are also some predictions that delay in the cycle may cause the sun to suddenly burst into violent activity with another series of x-ray megaflares in
the X-20+ range, or even cause another Carrington event.
NASA's THEMIS satellite found that a 4,000-mile-thick layer of solar particles has gathered and is rapidly growing within the outermost part of the
magnetosphere, a protective bubble created by Earth's magnetic field. This is causing a breach in the planet's magnetic defenses. This is not a
problem at solar minimum, but at peak solar activity it could allow up to twenty times more plasma to impact Earth, making some of the worst solar
storms in decades possible.
Solar Shutdown
The sharp downturn in the sunspot cycle may mark the point where solar activity significantly decreases as the sun enters the beginning of another
minimum period. The result of this would be dramatic cooling; in some ways, it could have worse consequences than global warming. The lack of activity
in solar cycle 24 has prompted concerns about this.
This shift in global temperature could have a substantial impact on the agricultural belts of Europe, North America, and Russia, which are responsible
for a substantial part of the world's current food supply These are vulnerable to a downward temperature change of more than a few degrees. Greater
decreases in temperature are certainly possible if the sunspot cycle fails to gain momentum.
For Europe, the possible collapse of the gulfstream and its underwater equivalent, the Atlantic warm convector, could signal a massive change in
climate. The warming these currents provide prevents European countries from being as cold as those on the equivalent latitudes in North America.
Without them, some of the most populated parts of the European continent would be under Arctic conditions.
Cosmic Rays and Climate Change
Dmitriev is not the only scientist who thinks this influx of cosmic rays has a major part to play in the recent increases in global temperature.
Henrik Svensmark is the head of Center for Sun-Climate Research at the Danish Space Research Institute. In his book The Chilling Stars: A New Theory
of Climate Change, he suggests that when cosmic radiation, especially protons, hit Earth's atmosphere, the reaction they cause has the effect of
creating clouds. The more cosmic rays there are the greater the cloud cover.
A shutdown in solar activity and a decrease in the magnetic field of the sun leave our planet more open to the influx of plasmic energy from outside
the solar system. This then leads to an increase in cloud cover and the kind of climate change we are now seeing. Svensmark predicts we could be about
to enter a new Maunder minimum-like period and that global temperatures are about to rapidly cool.
Dr. Nir Shaviv, an astrophysicist, also thinks cosmic rays affect our planet's climate. By reconstructing the temperature on Earth over the past 500
million years, Shaviv thinks he has found that changes in the amount of cosmic rays are responsible for more than two-thirds of Earth's temperature
changes, making it the most important driver of climate change over long periods of time.
Shaviv hypothesizes that the sun's passage through the spiral arms of the Milky Way appears to have been the cause behind the major Ice Ages over the
past billion years. He has correlated variations in the cosmic-ray flux to the solar system's orbit around the center of the galaxy and through its
spiral arms. In the more crowded spiral arms, like our Orion arm, there is a higher density of cosmic rays. Shaviv agrees with Svensmark that the
result of this increase is that Earth becomes cooler.
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