iridium motorola
Solar Storms and You: Human Impacts
Related figures and tables.
Solar Storms and Their Human Impacts
References, Books, Web sites
A Roman garrison was mistakingly ordered to march to the coastal town
of Ostia because Tiberius Caesar in 34 AD thought that the red glow
seen on the northern horizon at night was Ostia in flames. (The
Aurora, p.12) In China, the "Yellow Emperor" in 2000 B.C was conceived
during an auroral display. Up until very recently, this was about all
you could find to indicate that there were genuine 'other-worldly'
influences upon us instigated by the rather passive sightings of
sunspots or aurora. Even today, the average person is unaware of
either sunspots or aurora since neither are easily observable.
In just one generation, our reliance upon uninterrupted power
supplies to run our computer-rich, internet-laced, civilization; our
colonization of near-earth space with hundreds of billions of dollars
of satellite; and manned human activity, have placed all of these
enterprises at risk for damage by solar storms. Like settlers to
Kansas discovering tornadoes for the first time, we now have to reach
a grudging accommodation with aurora and their invisible confederates
that ply the ether above our heads. Unlike these settlers, however, we
have to be frequently reminded that there is a problem at all.
Fortunately, many examples of what this solar mayhem can do are easy
to come by.
Aurora
Forecasts: To find out if one will be near you!
SECEF Aurora
Resources page.
Great Aurora to
1938
Hello? Is anyone there?
Beginning with the invention of telegraphy in 1841 and the telephone
in the 1870's, vast systems of telephone and telegraph lines were
strung-up across many of the continents. It didn't take very long
before these new modes of communication began to turn up, not just an
occasional long-distance call from Aunt Mabel, but some entirely
unintended messages from Mr. Sun. During solar storms, "earth
currents" induced by the changing terrestrial magnetic field, were so
powerful that telegraphers didn't need a battery to send their
messages down the line; Some were even treated to near-electrocution!
Telegraph
Technology Handbook
History of the
Telephone
You can also find many references to earth current problems in
the American Journal of Science and Arts, (e.g. vol. 29, May 1860)
William Ellis of the Royal Greenwich Observatory provided the first
solar storm forecast in 1879 informing the telegraphic community that
sunspots are correlated with periods of strong auroral activity. He
noted that in the most recent years, there was little magnetic
activity, and that telegraphic technology had taken a turn towards
even more sensitive apparatus, and thousand-mile cables. He worried
that with the next solar maximum only a few short years away, the new
technology would be even more susceptible to magnetic 'storm' damage.
Nobody cared.
By 1881, as if on queue, and after a lull in numbers of 'mysterious'
surges, a new generation of reports began to accumulate as the solar cycle
reached its maximum. Once again telegraph lines in Boston and London
operated without batteries as auroral currents began to surge.
NOAA Earth magnetic
Field resource page.
For other references to magnetic storm disturbances, consult the
Journal of the Society of Telegraph Engineers and Electricians, vol. 1-10.
As solar storm particles arrive at the Earth and enter the
magnetosphere, they temporarily set-up an invisible, circulating flow
of charged particles around polar regions of the earth: The Ring
Current. This current causes magnetic field fluctuations near the
ground which in turn induce currents to flow in wires. This accounts
for the shenanigans we have just encountered in long telegraph lines.
But it doesn't matter if these wires are under the ocean because
electromagnetic energy can pass through water with little hindrance.
In the Atlantic Cable between Scotland and New Foundland, voltages up
to 2,600 volts were recorded during the March 1940 magnetic storm.
A February 9-10, 1958 storm caused severe interruptions of telephone
service on Western Union's North Atlantic telegraph cables, and
disrupted phone calls carried by the Bell System's coaxial cable link
between New Foundland and Scotland.
NOAA's Primer on the Space
Environment
SECEF Primer on Solar
Storms
History
of the Trans-Atlantic Cable
"Hey...Who turned out the lights!"
Spectacular auroral displays can be breath-taking, but too much of a
good thing can spell serious trouble. The pathways for this trouble
can be as common as the power lines that criss-cross your own
neighborhood.
The March 24, 1940 storm caused a temporary disruption of electrical
service in New England, New York, Pennsylvania, Minnesota, Quebec and
Ontario. A storm on February 9-10, 1958 caused a power transformer
failure at the British Columbia Hydro and Power Authority. On August
2, 1972, the Bureau of Reclamation power station in Watertown, South
Dakota was subjected to large swings in power line voltages up to
25,000 volts. Similar voltage swings were reported by Wisconsin Power
and Light, Madison Gas and Electric, and Wisconsin Public Service
Corporation. A 230,000-volt transformer at the British Columbia Hydro
and Power Authority exploded, and Manitoba Hydro in Canada recorded
power drops from 164 to 44 megawatts in a matter of a few minutes, in
the power it was supplying to Minnesota.
Have a nice day!
Power Outages:
American Geophysical Union, March 1997 report on transformers and
solar storm effects.
For more information about power surges, read
'Our Turbulent Sun' by Kendrick Frazer, (Prentics-Hall, 1980).
The US Power
Grid--assorted information.
Perhaps the most dramatic, recent impact occurred in March 1989
during the peak of the last sunspot cycle, when the sun produced one
of the most powerful storms ever recorded. On March 13, 1989 Alaskan
and Scandinavian observers were treated to a spectacular auroral
display. In fact, this display was seen as far south as the
Mediterranean and Japan. Although many millions of people marveled at
this beautiful spectacle, many millions more were not so happy about
it. Hydro-Quebec on Saint James Bay did the best it could to stabilize
the power surges its lines received but ultimately failed the
challenge. For 9 hours, large portions of Quebec were plunged into
darkness.
March 1989
Blackout in Quebec IPS Radio and Space Service report.
According to John Kappenman, who is in charge of Transmission Power
Engineering at Minnesota Power and Electric, the frequency of
transformer failures is higher in geographic regions where magnetic
storms are also more common such as the Northeastern US region which had
60% more transformer failures. Moreover, the number of failures follow
a solar activity pattern of roughly 11 years. A conservative estimate
of the damage done by geomagnetic storms to transformers by Minnesota
Power and Electric was $100 million. Oak Ridge National Laboratories
estimated that the collateral impact to the economy of another March
1989 storm of only slightly greater severity would produce a Northeast
United States blackout, and cause $6 billion in damage. The North
American Electric Reliability Council placed the March 1989 and
October 1991 storm events in a category equivalent to Hurricane Hugo
or the San Francisco earthquake in their impact upon the national
economy.
Power Outages:
AGU Report on transformers and solar storm effects
Minnesota Power and Electric
report by John Kappenman on transformer outages.
Just as good for generating large induced currents as telegraph and
power lines are long, uninterrupted segments of oil and natural gas
pipelines. Currents flowing in pipelines are known to enhance the rate
of corrosion over time, and this can have catastrophic effects. On
June 4, 1989 a powerful gas pipeline explosion demolished part of the
Trans-Siberian Railroad engulfing two passenger trains in flames.
Rescue workers at the Ural Mountain site worked frantically to rescue
passengers. Of the 1200, all but 500 could be saved. Many of the
victims were children bound for holiday camps by the Black Sea.
Apparently gas from a leak in the pipe line was ignited by the two
passing trains. The gas settled into the valley that the trains were
passing through at the time. Rumors of sabotage were wide spread among
the local population, but no one suspected the aurora and the
invisible corrosive currents it spawned over time. The Alaskan oil
pipeline is a newer technology and is specifically designed to
minimize these geomagnetic currents, but the Siberian pipeline was an
older technology without these safeguards in place.
Summaries of newspaper reports in this catastrophe can be found at
IMAGE/POETRY's Space
News page.
You would think that all this catastrophe would surely be picked up by
major newspapers, but you would be quite wrong. The Chicago Tribune,
The Washington Post and the London Times were curiously silent about
the March 1989 blackout. Only the Toronto Star on March 13, 1989
reported that "Huge Storms on Sun linked to blackout that crippled
Quebec" The problem is that many of these calamitous events are at the
nuisance level, and they are seemingly unrelated. No grand conspiracy
is afoot, and only small, geographically remote segments of humanity
seem to be affected. But now times have definitely changed as we enter
the Satellite Era with hundreds of millions of subscribers relying on
the flawless and reliable working of satellite technology.
NOAA list of Large Solar Flares
1976-1998.
They call them 'Satellite Anomalies'
There is a long list of satellites that have been confirmed to have
been directly affected by solar storms and the enhanced particle
fluxes the satellites intercept. It is also this category of impacts
that seems to contain the greatest controversies among satellite
designers, insurance companies, and scientists working behind the
scenes.
J-Track is a 3-D
orbit simulator for all major satellites
National Academy of
Sciences report on the practical consequences of Space Weather and
satellite impacts.
GOES-4 ( November 26, 1982) visible and infrared spin-scan radiometer
was disabled for 45 minutes after the arrival of high-energy protons
from a solar flare. Marecs-B, a marine navigational satellite, was
disabled by the strong electrical currents flowing during a week of
intense auroral activity in February 1982. GOES-7 weather satellite
lost half of its solar cells during a large proton release by the sun
during the powerful March 13, 1989 storm which cut the operating life
span of this satellite in half. ANIK E-1 and E-2 (January 20-21, 1994)
two Canadian communications satellites were disabled due to the
elevated activity of high-energy electrons in the magnetosphere.
A similar disturbance in August 1993 was implicated in causing
temporary pointing errors in five Intelsat satellites. The Intelsat-K
satellite began to wobble a few hours before the January 20, 1994
event which affected the Anik E1 and E2 satellites. Intelsat-K also
experienced a short outage of service during this time. On January 11,
1997 at 6:15 AM EST, AT&T experienced a massive power failure in its
Telstar 401 satellite. A few hours before Telstar 401 began to show
signs of malfunctioning, the GOES-8 weather satellite experienced its
own difficulties. Meanwhile the plasma from a solar storm had just
arrived hours before.
January 1997 CME
--The technical details of the January 1997 coronal mass ejection
October 7,
1995 Intelsat 511 Satellite outage caused by the sun; IPS Radio and Space
Services report by Richard Thompson.
Information about the ANIK satellite failures can be found in articles
appearing in Aviation Week and Space Technology, Jan 31, 1994 , and
in Satellite Communications, March 1994.
It is important to realize that simultaneous events need not be
correlated. The SOHO satellite recently showed two comets plunging
into the sun, and hours later, the sun disgorged a massive cloud of
plasma. These are "simultaneous" events but not connected by cause and
effect. Also, if there are thousands of working satellites in space,
why is it that a specific storm only seems to affect a few of them, if
any at all? Despite the dramatic consequences for Telstar 401, no
military satellites were apparently affected by this particular storm,
and Hughes Space and Communications which manufactured over 40% of
the commercial satellites now in orbit, had also not received any
reports of any anomalies related to the storm among other satellites
of similar type. If solar storms are so potent, why don't they take-
out many satellites at a time? Solar storms are at least as complex as
tornadoes, and we know that tornadoes can flatten one house while
leaving its neighbors untouched, but that doesn't persuade us to deny
the existence of tornado damage. We can see tornadoes coming with our
own eyes. Not so for solar storms: The ultimate Stealth Bombers of the
solar system.
CNN's article
on the SOHO Comets
During the last year it has become popular to blame any odd event on
El Nino from a 'bad hair day' to droughts in Texas. Literally billions
of dollars of commercial satellite insurance money rides on whether a
satellite failure was an 'Act of God' ( uninsurable) or a subtle
satellite design flaw ( insurable ). A scientist's guarded opinion
cannot be submitted as evidence to support one side or the other of an
insurance claim. There must be a rigorous and precise statement in the
court of law that 'Event A caused Satellite B to fail, but did not
affect at the same time Satellites C, D, E ....Z'. Usually, this kind
of guarantee cannot be provided scientifically because the satellite
is unrecoverable, and only apparent correlations in time and space can
be offered as evidence that a specific solar event affected a
satellite in a specific way, leaving its neighbors unaffected. This
often allows commercial satellite companies to claim that no natural
'Act of God' event was indisputably involved. Sometimes, after all,
satellites DO simply malfunction in orbit after many years of
operation.
"Insurers Beleaguered by Rash of Failures in '98", Space News, August 31,
1998.
"Insurers Battle with Satellite Manufacturers over Quality Control",
Space News, April 28, 1997.
It was widely reported in the media such as Aviation Week and
Space Technology, that a solar storm had damage the Telstar 401
satellite, but some scientists were not so ready to implicate the
solar storm as the proximate cause of the damage to the satellite.
Robert Hoffman, a NASA scientist and PI for the POLAR satellite, was
quoted in Aviation Week and Space Technology as saying that,
although the satellite was located in an affected area of the
magnetosphere,
"We have no idea what caused the failure".
Physicist Geoff Reeves at Los Alamos National Laboratory also
supported this cautious position
"We know that these conditions
can cause problems for satellites, but unless we can go up with the
space shuttle, bring the thing back, and look at it in the lab, we'll
never know exactly how it failed"
"Faulty Materials Blamed in Failure of Telstar 401", Space News, May
26, 1997.
Where's the beef?
Scientists do, however, know a thing or two about how radiation
affects satellites, at least in the case of research satellites which
represent a very non-threatening population. When research satellites
fail, scientists do not get paid satellite insurance dividends, nor
are there national security issues involved. Instead, some scientists
may quietly lose their careers, and taxpayer money is silently lost in
the accounting book work.
The most destructive ingredient of solar storm activity for satellites
seems to be in the high-energy electrons rather than the other types
particles. These electrons do their damage by producing 'deep
dielectric charging' in unprotected parts of the satellite. Data taken
by the SAMPEX satellite of the energetic electrons near geosynchronous
orbit, against the times when the Anik satellites were affected, shows
that the failures happened near the peaks of this activity. Data
provided by Rice University and NOAA and NGDC scientists show that
satellite surface charging 'anomalies' detected by the GOES-4 and
GOES-5 spacecraft in geosynchronous orbit, correlate very well against
a period when electrons were injected into this orbit due to the
passage of a disturbance from the geotail region into the inner
magnetic field regions around the earth. Some satellite designs, or
satellite orbital locations, seem to have a higher risk for solar
storm affects than others.
SAMPEX
information and plots.
National Research Council
satellite anomaly plots
One recent, and spectacular, satellite outage occurred on May 17, 1998
when the PanAmSat's Galaxy IV satellite, insured for $165 million,
lost control, and shut down service for millions of pagers in North
America. Hughes investigators believe this was due to a rare buildup
of crystals in a switch designed to control the flow of electricity to
satellite processors. Hughes vice president Jeff Grant is quoted as
saying that Hughes officials do not feel that the processors on the
other 30 satellites of similar model type (HS-601s) are likely to fail
but that,
"We feel we could have another processor failure on a
spacecraft in orbit. I don't think we would be immensely surprised"
Jeff Grant's quote is from--Space News, July 13, 1998.
The electrostatic discharge scenario is mentioned in--Space News, July
13, 1998.
The crystal build-up scenario is discussed in--Space News, August 17,
1998.
Was there a solar storm or other geomagnetic storms in progress at
that time? Between April 27 and May 6 NASA satellites detected 7 CMEs
and two very powerful solar flares which temporarily produced a new
radiation belt orbiting the Earth. Several magnetic storms were
recorded on earth on May 2 and May 4 causing New England power
companies to reduce their power-sharing capacity with Canada as a
precaution. On May 2, the Equator-S satellite failed, but the
connection between the solar storms and the satellite failure is
currently in dispute. The May 6 storm affected the POLAR satellite
which had to be shut down for several hours to recover. According to
plots made of the high-energy electron fluxes near the Earth by Geoff
Reeves ( Los Alamos Laboratories), the period from May 15-19 recorded
the maximum electron fluxes during this storm period. So, did Galaxy
4 fail because of the high-energy electron environment or because of
faulty switch design? This is the core of the controversy over
commercial satellite failures.
ISTP News -- May,
1998 discusses satellite failures.
Equator-
S news and mission updates.
Iridium satellite losses are mentioned in--Space News, May 18, 1998.
Of particular concern are the so-called 'phantom switches' where data
bits are switched from '1' to '0' or vice versa because of a discharge
in the electrical device caused by a high-energy particle strike. A
nearly perfect correlation can be found between specific bit-switches
and energetic electron enhancements detected by the GOES-7 and
METEOSAT-3 satellites. The switches seemed to happen most often during
periods when the electron impacts remained high for several days at a
time. It isn't a single intense storm that seems to do the dirty work,
but a sustained period of high electron 'storm' activity near the
spacecraft. Even commercially available hand calculators on-board the
MIR have been used to track bit switches.
Spacecraft
Anomalies due to Solar Storms How satellites are affected, with
examples.
Space Environment Effects at the NASA,
Marshall Space Flight Center.
Radiation
Effects at the NASA Goddard Space Flight Center.
Solar activity doesn't have to take a direct swipe at a satellite to
do it harm by throwing high-energy particles at it. There is an old
Irish saying 'May the road rise up to meet you". For satellites during
heightened solar activity, the earth's atmosphere can puff up like a
balloon and offer increased atmospheric friction. The premature demise
of such satellites as the Solar Maximum Mission (SMM April 1990) and
Skylab(July 1979) is the result. During the March 1989 storm, U.S.
Space Command had to post the new orbital elements for over 1000
objects whose orbits had been affected by the momentarily increased
air resistance hundreds of miles above the earth's surface.
That was then...this is now!
Between 1997 and 2007 it is estimated that as many as 1000 new
satellites will be launched with 75% for commercial use. Most will
be located in nearly a dozen satellite networks located in low earth
orbit (LEO) between 200 and 800 km. Among the heavily used satellites
already in place are the Motorola Iridium network of 66 satellites in
LEO, the Intelsat network of 25 satellites in geosynchronous earth
orbit (GEO) near 34,000 km, and the Global Positioning System with its
24 satellites at 11,000 miles costing $10 billion. Individual
Investor magazine ( June 1998) announced on its cover 'The Sky's the
Limit:In the 2st century satellites will connect the globe'. The
International Telecommunications Union in Geneva has predicted that
between 1996 to 2005, the demand for voice and data transmission
services will increase from $700 billion to $1.2 trillion, and that
the fraction carried by satellite services will reach a staggering
$80 billion. To meet this demand, many commercial companies are
launching aggressive networks of LEO satellites (See table). But there
is more than satellite technology riding on the line for the next
solar maximum.
Planned Commercial Satellite Networks for 1999-2005
Computer
technology History
Also read "Merrill Lynch Bullish on Space Industry Worldwide"
published in the 'International Space Industries Report', May 7, 1998.
Most people have an instinctive fear of radiation and its potential
biological effects. No matter where you live, you receive a free dose
each day of environmental radiation which adds up to 360 millirems (4-
5 chest X-rays) per year, and you have no control over this. Cancer
risks are generally related to radiation exposure, and one obtains
between 12 and 100 cancers per 100,000 people for every 1000 millirems
of additional dosage per year. This has been translated into
'acceptable' risks and dosage levels for different categories of
individuals and occupations. Some careers are worse than others for
producing large lifetime dosages such as, nuclear plant operators and
astronauts.
During the Apollo program, there were several near-misses between the
astronauts walking on the surface of the Moon and a deadly solar storm
event. The Apollo 12 astronauts walked on the Moon only a few short
weeks after a major solar proton flare would have bathed the
astronauts in a 100 rem blast of radiation. Another major flare that
occurred half way between the Apollo 16 and Apollo 17 moonwalks would
have had a much more deadly outcome had it arrived while astronauts
were outside their spacecraft playing golf. Within a few minutes, the
astronauts would have been killed on the spot with an incredible 7000
rem blast of radiation.
Spaceflight
Radiation Effects on Humans: Dosages and predictions.
The MIR space station has been inhabited for over a decade, and
according to Astronaut Shanon Lucid, the daily dosage of radiation is
about equal to 8 chest X-rays per day. During one solar storm towards
the end of 1989, MIR cosmonauts accumulated in a few hours, a full-
years dosage limit of
radiation. Meanwhile, the Space Station will be assembled in an orbit
which will take it through the South Atlantic Anomaly. Moreover, Space
Station assembly will involve several thousand hours of space walks by
astronauts. The main construction work will occur between the years
2000 and 2002 during the sunspot maximum period of Cycle 23. We can
expect construction activity to be tied to solar conditions in a way
that will frustrate the scheduling of many complex activities and the
launches of Space Station components.
Shannon Lucid's MIR adventures are reported in
Scientific American, May 1998.
So, what do we do?
The next solar cycle is already upon us, and if the blackouts,
communication outages and satellite problems of the last few cycles
are any indication, we could be in for some interesting news
headlines, or interesting denials of cause and effect.
Increasingly more people are becoming sensitized to the need for
paying attention to solar storm effects upon satellite operability.
For instance, in Satellite News (June 1, 1998 p.3) an essay notes
that,
"...The sun is nearing the peak of its 11-year activity cycle,
signaling an increase in solar flares. This may lead to waves of
radiation and high energy protons bombarding the planets throughout
the coming months and years, rendering billions of dollars of
satellite constellations vulnerable to extreme conditions."
Cycle 23
Prediction of its maximum and properties.
Space Weather Today
NOAA's Official Space Weather
Today
Space Weather
Space Weather Forecasting
So, why not make all satellites 'radiation hardened' or equip them
with lots of radiation shielding? In one word 'Cost'.
Shielding is dead weight, but it costs just as much as million-dollar
technology to put into space. So, satellites are designed with the
minimum shielding that the engineers think, they can get away with to
keep the satellite functioning without breaking the bank. There is
nothing wrong with this strategy, provided you are willing to take the
gamble that you can anticipate accurately what the typical environment
will be like during the satellite's lifetime. If you guess wrong, the
shielding is inadequate and your satellite is lost. As pointed out by
William B. Scott in Aviation Week and Space Technology magazine,
"Austere defense budgets also have increased reliance on more
affordable, but perhaps less robust, commercial off-the-shelf
hardware...expensive radiation-hardened processors are less likely to
be put on some military satellites or communication systems now, than
was once the case according to USAF officers...newer chips are much
more vulnerable than devices of 10-15 years ago"
"Operations Place High Value on Space Weather Forecasting" in
Aviation Week and Space technology, September 1, 1997.
"Stormy Weather in Space" in IEEE Spectrum, June 1995.
"Solar Flares Show Vulnerability of High-Tech Communications" in
Florida
Today Space Online
From the first day of the Space Age, engineers recognized that the
geiger counters inside scientific research satellites such as Vanguard
and Explorer were madly ticking away the cosmic ray traffic even from
inside the skin of the satellite. There are many well-known elements
to this problem that are by no means a mystery to satellite
designers. In the mid-1960s, NASA became a leader in developing and
refining models of the earth's environment through the Trapped
Radiation Environment Modeling Program (TREMP). The most recent of
these models for the high-energy
electrons and protons are called AE-8 and AP-8 models. Because they
are strictly statistical averages over time and space, these 30-year-
old models do not include solar storm events which can produce a years
worth of radiation damage in a few hours. Despite the incompleteness
of the AE and AP-8 models, they are in widespread use today. NASA has
now begun to invest millions of dollars in research satellites and
newer generations of models that will be substantially more accurate.
They will for instance, not average many different data together, but
will follow the detailed changes in many different data sets across
time, space and energy.
As 'physics-based' models, they will take advantage of more than 30
years of advances in plasma physics theory to improve upon their
predictability. But the new models
are not ready yet, and so satellite designers rely on older models to
calculate spacecraft shielding.
JPL's Radiation Effects model.
Boeing's MACREE model.
"US scientists warn of rise in solar flares" in Space News, December 1,
1997.
"NASA urged to pursue study of radiation effects" in Space News,
January 6, 1997.
"Space weather monitoring faces funding woes" in Space News, June 30,
1997.
In an age where "cheaper, faster and smaller' drives many
satellite designs, satellites have become more susceptible to solar
storm damage than their less sophisticated predecessors. Amazingly, as
more satellites become disabled by 'mysterious' events, we are having
to rediscover the importance of old lessons in satellite design and
the costs are passed on to us as the end users.
"Satellite makers Use Cheaper, Faster Approach"--Space News, Feb 18,
1998.
"Protecting US assets in space" in the International Space Industry
Report, June 8, 1998.
Meanwhile, the next time you hear about power outages or satellite
failures in the next few years, don't blame 'El Nino', instead you
might also consider blaming ol' Mr. Sun. After all, he's been up to
the same old shenanigans for over a century now. Perhaps this time we
will find ourselves a bit more prepared for his mischief!
references
For more information about solar storms and the many surprising
connections between the sun and the earth that invisibly affect you,
visit the NASA Office of Space Science's Sun-Earth Connection
Education Forum and the NASA IMAGE satellite web sites at
sunearth.gsfc.nasa.gov and
image.gsfc.nasa.gov/poetry.
The resources were available as of September 23, 1998
VLF Sounds What
the earth's environment sounds like.
POLAR
Satellite: More VLF sounds from geospace.
Magnetic
Declination Primer How your compass works and the magnetic pole.
The North
Magnetic Pole Current and past locations plotted
Auroral Acuostic
Sounds: What they are, how they may be made.
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