Solar Storm (Compilation)

Posted: August 12, 2008 in Life
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Stronger Solar Storms Predicted; Blackouts May Result

John Roach
for National Geographic News
March 7, 2006
The next 11-year solar storm cycle should be significantly stronger than the current one, which may mean big problems for power grids and GPS systems and other satellite-enabled technology, scientists announced today.

The stronger solar storms could start as early as this year or as late as 2008 and should peak around 2012.

“We predict the next solar cycle will be 30 to 50 percent stronger than the last cycle,” said Mausumi Dikpati, a solar scientist with the National Center for Atmospheric Research in Boulder, Colorado, yesterday in a telephone briefing with reporters.

The last cycle peaked in 2001.

A new technique enabled the scientists to better predict the severity of the next cycle. The technique, called helioseismology, allows researchers to “see” inside the sun by tracing sound waves reverberating inside the sun—creating a picture of the interior like ultrasound creates a picture of an unborn baby.

“For the first time we can predict the strength of the 11-year solar activity cycle using computer simulations of the sun’s physics,” Dikpati said.

Storms in the Sun

Solar storms are linked to twisted magnetic fields in the sun that suddenly snap and release tremendous amounts of energy. The storms can disrupt satellite communications, cause power outages, and expose astronauts to high amounts of radiation.

Predicting space weather is becoming more important as more people rely on technology that solar storms can disrupt, according to Richard Behnke, director of upper atmosphere research with the National Science Foundation in Arlington, Virginia.

“This prediction of an active solar cycle suggests we are potentially looking at more communication and navigation disruptions, more satellite failures, possible disruption of electric grids and blackouts, more dangerous conditions for astronauts—all these things,” Behnke said during the briefing.

Space Weather

Solar storms tend to occur near sunspots, cool regions on the sun’s surface that appear as dark blotches. Scientists believe the spots result from concentrated magnetic fields inside the sun.

The number and intensity of sunspots fluctuates over time, reaching a peak about every 11 years. This 11-year pattern is known as the solar cycle.

Joseph Kunches, chief of the forecast and analysis branch of the National Oceanic and Atmospheric Administration’s Space Environment Center in Boulder, equated the space weather forecast to the annual hurricane forecast.

“The kinds of questions that are posed to hurricane forecasters also come to us in terms of space weather,” he told reporters.

“When is the next cycle going to start? How strong will it be? When will it quiet down? And compared to, say, the last [cycle in] recent memory, what are the effects going to be?”

Stormy Forecast

The new forecast draws on new understanding of how plasma currents in the sun’s interior generate sunspots and the related solar storms. These plasma flows transport, concentrate, and help spread out solar magnetic fields.

Two major plasma flows govern the cycle, the researchers said.

The first, known as the meridional flow pattern, circulates between the sun’s equator and its poles over a period of 17 to 22 years and acts like a conveyor belt of sunspots. The flow transports imprints of sunspots that occurred over the previous two sunspot cycles.

This imprint is carried into the interior, where scientists believe the sunspot-producing magnetic fields are generated. New sunspots form based on the imprints created during the most recent cycle.

The second flow results from the sun rotating faster at the equator than it does near the poles. This periodically concentrates the solar magnetic field at the equator, leading to peaks in solar storm activity, the researchers said.

The team expects the next cycle to begin in late 2007 or early 2008, which is about 6 to 12 months later than the cycle would normally start. The researchers’ model shows the plasma circulation has slowed down during the current cycle.

David Hathaway, a solar astronomer with NASA’s Marshall Space Flight Center in Huntsville, Alabama, said that models used by him and his colleagues to predict the next solar cycle agree with the greater activity predicted by Dikpati’s model.

But Hathaway differs on the timing.

According to Hathaway’s team’s analysis of past solar cycles, intense cycles are preceded by shorter cycles. This would suggest that the next cycle will start by the end of this year or early next year.

“At this point, we are anxiously awaiting the appearance of those first spots from the new cycle,” Hathaway said at the briefing.

Sunspot Cycles: Deciphering the Butterfly Pattern

John Roach
National Geographic News
February 4, 2005
A little more than 150 years ago, scientists learned that the number of sunspots (temporarily cool, dark areas) on our sun waxes and wanes over a period of about 11 years. About 90 years ago, scientists learned that there’s a butterfly-shaped pattern to this cycle. Now they are trying to learn what drives that pattern.

Understanding what generates the sunspot pattern may allow scientists to provide better forecasts of solar storms, which can cause power outages and disrupt satellite communications on Earth.

But first, what are sunspots? What’s the sunspot cycle? And what’s this pattern?

Sunspots are thought to result from a shifting magnetic field inside the sun, explains Aimee Norton, a solar astronomer with the High Altitude Observatory at the National Center for Atmospheric Research in Boulder, Colorado.

The number of sunspots fluctuates over time, reaching a peak every 11 years. This 11-year pattern is known as the sunspot cycle and was discovered in 1843 by German astronomer Samuel Heinrich.

Not only does the number of sunspots fluctuate over the 11-year period, but so too do their locations, Norton said. Over the period, the sunspots migrate from about 35 degrees north and south latitude toward the sun’s equator.

In 1904 English astronomer Edward Maunder noticed an artful pattern to the cycle.

When the latitude and time of sunspots from an entire cycle are plotted on a map, the migration of sunspots toward the equator looks like two wings of a butterfly. Several cycles plotted together look like a trail of butterflies.

Solar Dynamo

Scientists are now trying to understand why the sunspot belt moves toward the equator over the course of the 11-year cycle. To understand this, Norton said, requires understanding the so-called solar dynamo.

“This is one of the major mysteries in solar physics,” she said. “The dynamo is a process by which the mechanical motions on and in the sun are converted into magnetic energy.”

Since sunspots are believed to be regions of intense magnetic field and since they increase and decrease over an 11-year cycle, scientists believe that the sun’s magnetic field must also increase and decrease in time.

“The cyclical nature of the sunspot cycle is strong evidence that the magnetic field within the sun is being regenerated during this cycle,” Norton said.

Generated by the flow of hot gases, the sun’s electric currents in turn generate magnetic fields.

Norton and her colleagues are building computer models of the various flows on and in the sun to help them understand the solar dynamo. This should, in turn, explain the reason for the sunspot migration pattern.

“Some details of the migration pattern as observed in spot behavior is beyond the current capability of dynamo models to produce, but it may be possible with more elaborate models now under development,” said Peter Gilman, a colleague of Norton’s at the High Altitude Observatory.

Best Theory

Gilman said there is no scientific consensus on why sunspot-migration diagrams take the shapes of butterflies. A leading theory is based on computer modeling by colleague Gilman’s colleague Mausumi Dikpati.

Dikpati’s models link the migration to a current of plasma called the meridional flow, which circulates between the sun’s equator and its poles. It’s all part of a process called the Hale cycle.

The flow is like a system of two conveyor belts, one in the northern hemisphere and one in the southern hemisphere. Each belt travels along the surface of the sun, from the equator to the pole (north or south, depending on the hemisphere). At its pole, each belt turns the corner, diving into the sun’s interior.

The flow makes its return trip to the equator through the convection zone, the outermost layer of the sun’s interior. As the belt approaches the equator, it turns and follows a path toward the sun’s surface, and the cycle begins again.

A single Hale cycle takes about 22 years, or two sunspot cycles. The thinking is that the two halves of the “conveyor belt” have similar sunspot patterns on them, which is why sunspot activity follows an 11-year cycle—half a Hale cycle.

According to Dikpati’s theory, sunspots leave an imprint on the surface flow. This imprint is carried into the interior, where scientists believe the sunspot-producing magnetic fields are generated. New sunspots form based on the imprints created during the most recent cycle.

By understanding the variation of the meridional flow’s speed and the sun’s past sunspot cycles, Dikpati and colleagues believe they may be able to forecast the timing and intensity of sunspot activity—and therefore of solar storms.

“In fact, in a very recent work, we are predicting the onset of the next cycle—cycle 24—will be late, because the meridional flow slowed down in the current cycle,” Dikpati said.

According to the forecast, the next solar cycle will begin in 2007 to 2008. That means that cycle 24 would begin about a half year late, or about 11 years and six months after the beginning of cycle 23.


The Great Storm: Solar Tempest of 1859 Revealed
By Robert Roy Britt
Senior Science Writer
posted: 06:00 am ET
27 October 2003

A pair of strong solar storms that hit Earth late last week were squalls compared to the torrent of electrons that rained down in the “perfect space storm” of 1859. And sooner or later, experts warn, the Sun will again conspire again send earthlings a truly destructive bout of space weather.

If it happens anytime soon, we won’t know exactly what to expect until it’s over, and by then some modern communication systems could be like beachfront houses after a hurricane.

In early September in 1859, telegraph wires suddenly shorted out in the United States and Europe, igniting widespread fires. Colorful aurora, normally visible only in polar regions, were seen as far south as Rome and Hawaii.

The event 144 years ago was three times more powerful than the strongest space storm in modern memory, one that cut power to an entire Canadian province in 1989. A new account of the 1859 event, from research led by Bruce Tsurutani of NASA’s Jet Propulsion Laboratory, details the most powerful onslaught of solar energy in recorded history.

Solar conspiracy

Space storms are created when the Sun erupts, sending charged particles racing outward, an expanding bubble of hot gas called plasma.

In 1859, four crucial events conspired at one moment, Tsurutani told SPACE.com.

“The plasma blob that was ejected from the Sun hit the Earth,” he said. That’s a relatively routine event. What preceded the strike was more unusual. “The blob came at exceptionally high speeds. It took only 17 hours and 40 minutes to go from the Sun to Earth.” Solar storms typically take two to four days to traverse the 93 million miles (150 million kilometers).

“The magnetic fields in the blob, called a coronal mass ejection, were exceptionally intense,” Tsurutani said. “And the fourth, most important, ingredient was that the magnetic fields of the blob were opposite in direction from the Earth’s fields.”

Earth’s magnetic field normally protects the surface of the planet from a continual flow of charged particles, called the solar wind, and even does a pretty good job defending against some storms. When a storm swept past Earth last Friday, it met up with magnetic field pointed in such a way that it thwarted the storm’s effects. That’s not always the case.

In 1859, the planet’s defenses were overwhelmed.

That was then

Society back then did not notice the storm the way it would today. The telegraph was 15 years old. There were no satellite TV feeds, no automated teller machines relying on orbiting relay stations, and no power grids.

Tsurutani said scientists can’t yet accurately measure or predict what the strength or direction of Earth’s magnetic field will be when a storm arrives. The storms themselves can be predicted. And Tsurutani says there will eventually be another one like 1859.

“It could very well be even more intense than what transpired in 1859,” he says. “As for when, we simply do not know.”

Bernhard Fleck, the European Space Agency’s project scientist for the Sun-watching SOHO spacecraft, says the next super space storm will be detectable, but that’s only half the story.

“A monster event of the magnitude described [by Tsurutani] we would easily recognize as something extraordinary with SOHO and other solar instruments,” Fleck said in an e-mail interview. But, he added, “We certainly wouldn’t know its full extent until arrival.”

During the 1859 flare-up, solar observers logged almost an entire minute during which the amount of sunlight doubled at the region of the flare.

“Such a strong white-light flare has never been seen since,” says Paal Brekke, SOHO deputy project scientist. “So if this type of flare happened, yes we would know right away.” But he adds that the orientation of Earth’s magnetic field would not be known. Future space-based observatories could address this blind spot in space weather forecasting.

Meanwhile, the blind spot became clear on Friday.

Forecasters at NOAA’s Space Environment Center, relying on SOHO pictures and data, warned of an impending set of storms that could disrupt communications and might set off colorful aurora Friday and Saturday. The forecast, along with two Jupiter-sized sunspots at the roots of the storms, gained widespread media attention.

But the first and larger of the storms passed by with far less effect than one might have been led to expect. In fact, they were both comparative drops in the space weather bucket.

Extreme measures

To get an idea of the strength of the 1859 storm, you have to wade into nT’s for a moment.

A space storm’s impact is measured in nano-Teslas (nT), Brekke explained. The lower the figure, the more powerful the storm. A moderate storm can be around -100 nT; extreme and damaging storms have been logged at around -300 nT.

The 1989 coronal mass ejection that knocked out power to all of Quebec, Canada measured -589 nT, Brekke said. The 1859 perfect storm was estimated to have been -1,760 nT. Brekke used three exclamation points in his e-mail delivering that number.

People on the ground are generally safe even in the worst space weather. But technology could be in trouble when the next super storm hits.

“In 1859, the technology was quite low in comparison to today’s technology,” Tsurutani said. “However the technology that we rely on today is much more vulnerable.”

A strong storm does its damage in part by inducing currents on power and communication lines, leading to potential overloads. Obviously, there are a lot more wires on Earth today, “so one might expect much worse problems if it occurred today.”

The charged particles can also zap satellites, as has occurred with handful of storms in recent years — events with far fewer charged particles than in 1859. A space storm also heats the upper level of Earth’s atmosphere, causing it to expand. That’s no good for satellites that can get caught up in air that didn’t used to be there.

“This can lead to enhanced satellite drag and possible loss of these to the atmosphere,” Tsurutani said.

Tsurutani and his colleagues — Walter Gonzalez of the Brazilian National Space Institute and Gurbax Lakhina and Sobhana Alex of the India Institute of Geomagnetism — reviewed known observations of the 1859 event’s solar and aurora output, plus accounts from the ground. They also used recently rediscovered historic data on Earth’s magnetic field from the Colaba Observatory in India.

The findings were published in a recent issue of the Journal of Geophysical Research.

Karl Kuehn imaged the northern lights from Greene, New York on Sept. 7, 2002.

A fiery coronal mass ejection (CME) took off from the Sun on Jan. 4, 2002.

If you’ve ever watched the lazy summer Sun redden as it settles with a stalling sigh into the welcoming bosom of Earth’s horizon, you might have thought it grew a little fat around the mid-section. Time seems to suspend itself as the fading star spreads out, gripping the evening stage like a performer reluctant to allow the next act, twilight, to begin.

Strange things happen in the gathering dusk.

A few people claim they’ve seen a brilliant and instantaneous green flash as the top of the fiery blob dipped out of sight. More common are reports of light pillars shooting straight into heaven just before the day’s goodbye.

Wrapped up in these strange phenomena are a curious combination of fact and myth — quite possibly not in the combination you imagine. The commonly held belief that the green flash is a myth, for example, is itself a myth. We’ve got a picture to prove it.able –>

And the idea that the Sun gets fatter and larger as it sets is flat wrong. Oh, it seems to. But what really happens involves some relatively simple atmospheric science and, to keep things interesting, a strong dose of illusion and a dash of mystery.

The flat Sun (and Moon)

Let’s imagine you’re not at your computer today. Instead, you’re wiggling your toes in the sand at Malibu.

Everyone around you is half-naked, of course, and when the reason for that soared directly overhead at Noon, its waves of radiation fried a lot of the exposed flesh. But now it’s evening, the Sun is preparing to depart, and the harshness has gone out of the rays. You know intuitively that some of the energy isn’t getting through.

The electromagnetic waves — light — are muddling through more atmosphere en route to your spot on the beach.

To envision why, you can draw two circles, one to represent the atmosphere and another one inside the first and slightly smaller. This is Earth. Now draw a vertical line that connects the 12 o’clock positions of both circles. From the same point atop the Earth circle, draw a horizontal line to the left until it intersects the outer circle of atmosphere; this line will be longer, and it points toward your imaginary setting Sun.

Back in the real atmosphere, molecules of water, oxygen and other things get in light’s way, refracting some of it, sending it off in new directions. With more atmosphere comes more refraction.

Here’s the important part: When the Sun is at the horizon, light from its bottom travels through just a bit more air than light from the top. This lower batch of light gets refracted upward, and so the Sun appears squashed, as though it’s being drawn up like a set of mini-blinds. Yet light from the left and right sides of the Sun travel through the same amount of atmosphere, so the Sun does not spread out — it’s horizontal dimension remains the same.

The squashed Sun effect happens to the Moon, too, when it is near the horizon.

The extent of the squashing changes with altitude and temperature, both of which alter air density. In a study this spring, Romanian scientist Zoltan Neda and colleague Sandor Volkan worked out the math on all this. They found that on a normal day in a place like Malibu, the Sun can appear 1.2 times wider than it is tall. But in the Arctic, the Sun can appear twice as wide as its height.

And from an airplane or a space shuttle, the width can appear 2.5 times greater than the height, Neda said in an e-mail interview.

This refraction causes another effect you might have noticed. Because the bottom of the Sun is visually drawing up, the Sun really does appear to slow down just before it sets, explained Neda, who is a professor of theoretical physics at Babes-Bolyai University.

Now as you ponder all of this from the beach in Malibu, you would probably not be alone if you argued, “Hey, you said the Sun does not get wider, but I can see with my own eyes that it is much larger overall at sunset than at midday.”

I wouldn’t argue with you, but I would ask Philip Plait about your perplexing observation.

Debunking a myth

In his new book, “Bad Astronomy” (Wiley & Sons, 2002), Plait argues across 10 pages against a long-held myth that the Moon is larger when near the horizon. You’ve no doubt noticed this when a full Moon rises and looms ridiculously huge, only to shrink an hour later. Scientists don’t know exactly what’s going on, but they do know that the whole thing is an illusion. If you don’t believe them, Plait suggests you conduct your own test.

Hold a pencil eraser at arm’s length, he writes, and you’ll see that the Moon measures the same size when it rises as when it’s high in the sky.

The illusion of a big Moon is all in our heads, Plait and other astronomers say. It has to do with the fact that most people (whether they know it or not) perceive the sky to have bounds, and they imagine it’s shaped more like an upside-down, shallow cereal bowl than half of a true sphere. Thus, our brains tell us the sky is farther away at the horizon than it is directly overhead. Our brains are further warped: When confronted with two same-sized objects, the more distant one is interpreted as being larger (this is called the Ponzo Illusion).

Combined, the two imaginings lead us to think the Moon is bigger when it rises, Plait says. In his book, however, he does not address whether the widely discussed “Moon Illusion” applies to the Sun (he’s busy dispelling other myths). So I asked him.

“Yes, the setting Sun suffers the same illusion as the rising Moon,” he said. “Anything on the horizon in the sky does that.”

Pillars and the green flash

Other weird things happen when the Sun sets, but you’ll need some patience and luck to spot these.

A solar pillar is a striking sight. Again, the Sun itself has little to do with the effect, other than sending earthward the necessary light.

A pillar is typically rendered in cold air by ice crystals falling from high clouds, explains Robert Nemiroff, an astrophysicist at Michigan Technological University and a researcher at NASA’s Goddard Space Flight Center. The crystals are sometimes flat, and air resistance will cause them to float flatly, rather than knifing downward on edge. Sunlight reflects off the crystals to generate what appears to be a column of light soaring into space.

The pillar looks like it comes from the Sun, but in reality it’s just a few miles away.

Finally, the rarest of all these tricks of light is the green flash. You’ll recall that we decided you’re at the beach, gazing out over the Pacific. You are there because it is a good place to see this rare and fleeting phenomenon. A low horizon with a long view is needed. A prairie can suffice, and an airplane will do nicely, too.

The key to the green flash mystery again lies in refraction, along with the fact that the Sun’s white light is actually made of many colors.

“The Earth’s atmosphere acts like a prism,” Nemiroff says. “Blue is refracted the most.” Red light is refracted the least. Green is somewhere in the middle.

At sunset, when refraction is most pronounced, there can actually be three images of the Sun — a blue one on top, a green one in the middle, and a red one at the bottom. Each overlaps the others.

So why don’t we see a blue flash? Because the blue light is scattered so severely that it doesn’t even reach our eye, Nemiroff says. Once in a while though, and typically for less than a full second, a bit of the green light gets through.

And all the while, as you feel the sand growing cooler and prepare to bid the Sun farewell, the red light has the most success travelling unimpeded through the extra atmosphere in its evening path, which explains the general color of your final moments in Malibu.

More Images

Huge solar storms could zap Earth, scientists warn

Next sunspot cycle may disrupt power, communications

Keay Davidson, Chronicle Science Writer

Tuesday, March 7, 2006

An 11-year epoch of increasingly severe solar storms that could fry power grids, disrupt cell-phone calls, knock satellites back to Earth, endanger astronauts in space, and force commercial airliners to change their routes to protect their radio communications and to avoid deadly solar radiation could begin as soon as this fall, scientists announced Monday.

When the solar cycle reaches its peak in 2012, it will hurl at Earth mammoth solar storms with intense radiation and clouds of high-speed subatomic particles millions of miles across, the scientists said.

A storm of that magnitude could short-circuit a world increasingly dependent on giant utilities and satellite communications networks. Such a storm in 1989 caused power grids to collapse, causing a five-hour blackout in Quebec.

Monday’s forecast was announced by scientists from agencies including NASA and the National Science Foundation, based on research centered at the National Center for Atmospheric Research in Colorado.

There is disagreement on exactly when the new cycle will begin — one key researcher predicted the cycle will start in late 2007 or early 2008, and another said it could begin either late this year or in early 2007. But they did agree that the most severe storms won’t begin popping on the solar surface for several years, but when they do, they’ll be huge.

The solar storms in the past have knocked out huge power grids and screwed up global electronics and data communications, but “the next sunspot cycle will be 30 to 50 percent stronger than the last one,” the scientists said in Monday’s statement.

Reaching that 50 percent threshold would make it the most intense solar cycle since the late 1950s and the second worst since the early 1700s, Peter Gilman, one of the researchers, said in a phone interview.

Astronomers will monitor the sun daily in the coming months to see how it’s doing. Early warning signs will be the formation of large groups of sunspots, which are clusters of solar magnetic fields that are cooler than the rest of the sun.

“I look (at telescopic images of the sun) almost every day, thinking, ‘It could be today,’ ” said David Hathaway, solar physics team leader at NASA’s Marshall Space Flight Center in Alabama. He compared it to “waiting for the first sparrow of spring.”

Solar storms can happen at any time during an 11-year solar cycle. However, by far the worst storms are likeliest to occur during the period known as “solar maximum,” or solar max for short. The last solar max was in 2001.

The scientists are confident of their forecast for 2012 because they’ve successfully used a new computer model to “forecast” the past. That is, they used records of old solar cycles to figure out how the sun should have behaved during eight past cycles, as far back as the early 20th century. They “forecast” the sun’s past behavior — “hindcasting,” they call it — “with more than 98 percent accuracy” the scientists said.

“I’m really excited about this (discovery),” said NASA’s Hathaway. “It’s based on sound physical principles, and it finally answers the 150-year-old question: What causes the sunspot cycle?”

The cycle’s victims could include space satellites. The coming storms could heat the upper levels of Earth’s atmosphere, causing it to expand and exert drag on low-flying satellites — perhaps enough drag to tug some of them back to Earth. Solar storms have been blamed for the U.S. Skylab space station’s premature fall back to Earth in 1979.

Air travelers could be affected, too. Since the end of the Cold War, to avoid headwinds, airlines have increasingly flown subpolar routes to get between the United States and other Northern Hemisphere continents quickly and cheaply. But during solar storms, they must avoid the poles and fly more southerly routes.

They do so partly in order to avoid having their radio communications disrupted over dangerous polar terrain and partly to avoid exposing passengers — especially pregnant women — to the increased radiation, said solar-storm expert Joseph Kunches, chief of the forecast and analysis branch of the U.S. National Oceanic and Atmospheric Administration’s Space Environment Center in Boulder, Colo.

The northern and northeastern portions of North America are historically more vulnerable to system outages caused by solar storms than California and most of the Western states, said Gregg Fishman, spokesman for the California Independent System Operator. That’s possibly because among other things, he said, there’s a higher iron and mineral content in the North and Northeast that conducts the ground current more easily and allows for more of an impact during solar storms.

E-mail Keay Davidson at kdavidson@sfchronicle.com.

Solar flare

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A solar flare observed by Hinode in the G-band. It can be seen as two narrow, elongated, bright structures (ribbons) over the southern part of the sunspot.

A solar flare is a violent explosion in a star’s (like the Sun‘s) atmosphere releasing up to a total energy of 6 × 1025
Joules.[1] Solar flares take place in the solar corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating electrons, protons and heavier ions to near the speed of light. They produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays.[2] Most flares occur in active regions around sunspots, where intense magnetic fields emerge from the Sun’s surface into the corona. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona.

X-rays and UV radiation emitted by solar flares can affect Earth’s ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb operation of radars and other devices operating at these frequencies.

Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized brightenings in a sunspot group. Stellar flares have also been observed on a variety of other stars.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly “active” to less than one each week when the Sun is “quiet”. Large flares are less frequent than smaller ones. Solar activity varies with an 11-year cycle (the solar cycle). At the peak of the cycle there are typically more sunspots on the Sun, and hence more solar flares.

Classification of flares

Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square meter, W/m²) of 100 to 800 picometer
X-rays near Earth, as measured on the GOES spacecraft. Each class has a peak flux ten times greater than the preceding one, with X class flares having a peak flux of order 10-4 W/m². Within a class there is a linear scale from 1 to 9, so an X2 flare is twice as powerful as an X1 flare, and is four times more powerful than an M5 flare. The more powerful M and X class flares are often associated with a variety of effects on the near-Earth space environment. Although the GOES classification is commonly used to indicate the size of a flare, it is only one measure.

Soft X-ray light curves showing solar flares of different sizes and durations. The red curve represents the total flux in the band 1 to 8 Angstrom, and the blue curve is the flux in 0.5 to 4 Angstrom. Basically, this means that the curves represent the evolution in time of the X-ray power emitted by the Sun in two energy ranges. Each one of the numerous spikes in the curves represents a temporary increase in the emission due to a solar flare.

Two of the largest GOES flares were the X20 events (2 mW/m²) recorded on August 16, 1989 and April 2, 2001. However, these events were outshone by a flare on November 4, 2003 that was the most powerful X-ray flare ever recorded. This flare was originally classified as X28 (2.8 mW/m²). However, the GOES detectors were saturated at the peak of the flare, and it is now thought that the flare was between X40 (4.0 mW/m²) and X45 (4.5 mW/m²), based on the influence of the event on the earth’s atmosphere[3]. The flare originated in sunspot region 10486, which is shown in the illustration above several days before the flare.

The most powerful flare of the last 500 years is believed to have occurred in September 1859: it was seen by British astronomer Richard Carrington and left a trace in Greenland ice in the form of nitrates and beryllium-10, which allow its strength to be measured today (New Scientist, 2005).

NASA has identified a more reliable predictor of which sunspot will flare, per the Ζ shape some sunspots exhibit just prior to erupting, and there is a very interesting probability of flaring classification for sunspots that is ongoing.

[edit] Hazards

Filament erupting during a solar flare, seen at EUV wavelengths that show both emission and absorption (the filament has both). The plasma physics involved in this process remains poorly understood, but it certainly involves the Sun’s magnetic field.[4]

Solar flares and associated Coronal Mass Ejections (CMEs) strongly influence our local space weather. They produce streams of highly energetic particles in the solar wind and the Earth’s magnetosphere that can present radiation hazards to spacecraft and astronauts. The soft X-ray flux of X class flares increases the ionisation of the upper atmosphere, which can interfere with short-wave radio communication, and can increase the drag on low orbiting satellites, leading to orbital decay. Energetic particles in the magnetosphere contribute to the aurora borealis and aurora australis.

Solar flares release a cascade of high energy particles known as a proton storm. Protons can pass through the human body, doing biochemical damage[citation needed]. Most proton storms take two or more hours from the time of visual detection to reach Earth. A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured[5], taking only 15 minutes after observation to reach Earth, indicating a velocity of approximately one-third light speed.

The radiation risk posed by solar flares and CMEs is one of the major concerns in discussions of manned missions to Mars or to the moon. Some kind of physical or magnetic shielding would be required to protect the astronauts. Originally it was thought that astronauts would have two hours time to get into shelter, but based on the January 20, 2005 event, they may have as little as 15 minutes to do so.

Hinode spacecraft

A new spacecraft Hinode, originally called Solar B, was launched by the Japan Aerospace Exploration Agency in September of 2006 to observe solar flares in more precise detail. Its instrumentation, supplied by an international collaboration including Norway, the U.K., and the U.S., focuses on the powerful magnetic fields thought to be the source of solar flares. Such studies shed light on the causes of this activity, possibly helping to forecast future flares and thus minimize their dangerous effects on to satellites and astronauts.[6].

Geomagnetic storm

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This article is about Geomagnetic storm. For other uses of “magnetic storm” and “magnetic storms”, see Magnetic storm (disambiguation).

Solar particles interact with Earth’s magnetosphere.

A geomagnetic storm is a temporary disturbance of the Earth‘s magnetosphere caused by a disturbance in space weather. Associated with solar coronal mass ejections (CME), coronal holes, or solar flares, a geomagnetic storm is caused by a solar wind shock wave which typically strikes the Earth’s magnetic field 24 to 36 hours after the event. This only happens if the shock wave travels in a direction toward Earth. The solar wind pressure on the magnetosphere will increase or decrease depending on the Sun’s activity. These solar wind pressure changes modify the electric currents in the ionosphere. Magnetic storms usually last 24 to 48 hours, but some may last for many days. In 1989, an electromagnetic storm disrupted power throughout most of Quebec
[1] — it caused auroras as far south as Texas
[2].

Historical occurrences

On 13 March
1989 a severe geomagnetic storm caused the collapse of the Hydro-Québec power grid in a matter of seconds as equipment protection relays tripped in a cascading sequence of events [3][4]. Six million people were left without power for nine hours, with significant economic loss. The storm even caused auroras as far south as Texas
[5]. The geomagnetic storm causing this event was itself the result of a Coronal Mass Ejection, ejected from the Sun on March 9, 1989.[6]

In August 1989, another storm affected micro chips, leading to a halt of all trading on Toronto‘s stock market
[7].

Since 1989 power companies in North America, the UK, Northern Europe and elsewhere have invested time and effort in evaluating the geomagnetically induced current (GIC) risk and in developing mitigation strategies.

Since 1995, geomagnetic storms and solar flares are observed from the Solar and Heliospheric Observatory (SOHO) joint-NASAEuropean Space Agency satellite.

[edit] Interactions with planetary processes

The solar wind also carries with it the magnetic field of the Sun. This field will have either a North or South orientation. If the solar wind has energetic bursts, contracting and expanding the magnetosphere, or if the solar wind takes a southward polarization, geomagnetic storms can be expected. The southward field causes magnetic reconnection of the dayside magnetopause, rapidly injecting magnetic and particle energy into the Earth’s magnetosphere.

During a geomagnetic storm, the ionosphere’s F2 layer will become unstable, fragment, and may even disappear. In the Northern and Southern pole regions of the Earth, auroras (aka Northern lights) will be observable in the sky.

Magnetosphere in the near-Earth space environment.

Geomagnetic storm effects

Radiation hazards to humans

Intense solar flares release very-high-energy particles that can be as injurious to humans as the low-energy radiation from nuclear blasts. Earth’s atmosphere and magnetosphere allow adequate protection at ground level, but astronauts in space are subject to potentially lethal doses of radiation. The penetration of high-energy particles into living cells can cause chromosome damage, cancer, and a host of other health problems. Large doses can be fatal immediately. Solar protons with energies greater than 30 Megaelectronvolts(MeV) are particularly hazardous. In October 1989, the Sun produced enough energetic particles that an astronaut on the Moon, wearing only a space suit and caught out in the brunt of the storm, would probably have died; the expected dose would be about 7000 rem. (Astronauts who had time to gain safety in a shelter beneath moon soil would have absorbed only slight amounts of radiation.) The astronauts on the Mir station were subjected to daily doses of about twice the yearly dose on the ground, and during the solar storm at the end of 1989 they absorbed their full-year radiation dose limit in just a few hours.

Solar proton events can also produce elevated radiation aboard aircraft flying at high altitudes. Although these risks are small, monitoring of solar proton events by satellite instrumentation allows the occasional exposure to be monitored and evaluated, and eventually the flight paths and altitudes adjusted in order to lower the absorbed dose of the flight crews.

Biology

There is a growing body of evidence that changes in the geomagnetic field affect biological systems. Studies indicate that physically stressed human biological systems may respond to fluctuations in the geomagnetic field. Interest and concern in this subject have led the International Union of Radio Science to create a new commission entitled Commission KElectromagnetics in Biology and Medicine[1] Current chair Dr. Frank Prato[2].

Possibly the most closely studied of the variable Sun’s biological effects has been the degradation of homing pigeons‘ navigational abilities during geomagnetic storms. Pigeons and other migratory animals, such as dolphins and whales, have internal biological compasses composed of the mineral magnetite wrapped in bundles of nerve cells. While this probably is not their primary method of navigation, there have been many pigeon race smashes, a term used when only a small percentage of birds return home from a release site. Because these losses have occurred during geomagnetic storms, pigeon handlers have learned to ask for geomagnetic alerts and warnings as an aid to scheduling races.

Disrupted systems

Communications

Many communication systems use the ionosphere to reflect radio signals over long distances. Ionospheric storms can affect radio communication at all latitudes. Some radio frequencies are absorbed and others are reflected, leading to rapidly fluctuating signals and unexpected propagation paths. TV and commercial radio stations are little affected by solar activity, but ground-to-air, ship-to-shore, shortwave
broadcast, and amateur radio (mostly the bands below 30 MHz) are frequently disrupted. Radio operators using HF bands rely upon solar and geomagnetic alerts to keep their communication circuits up and running.

Some military detection or early warning systems are also affected by solar activity. The over-the-horizon radar bounces signals off the ionosphere in order to monitor the launch of aircraft and missiles from long distances. During geomagnetic storms, this system can be severely hampered by radio clutter. Some submarine detection systems use the magnetic signatures of submarines as one input to their locating schemes. Geomagnetic storms can mask and distort these signals.

The Federal Aviation Administration routinely receives alerts of solar radio bursts so that they can recognize communication problems and forego unnecessary maintenance. When an aircraft and a ground station are aligned with the Sun, jamming of air-control radio frequencies can occur. This can also happen when an Earth station, a satellite, and the Sun are in alignment.

The telegraph lines in the past were affected by geomagnetic storms as well. The telegraphs used a long wire for the data line, stretching for many miles, using ground as the return wire and being fed with DC power from a battery; this made them (together with the power lines mentioned below) susceptible to being influenced by the fluctuations caused by the ring current. The voltage/current induced by the geomagnetic storm could have led to diminishing of the signal, when subtracted from the battery polarity, or to overly strong and spurious signals when added to it; some operators in such cases even learned to disconnect the battery and rely on the induced current as their power source. In extreme cases the induced current was so high the coils at the receiving side burst in flames, or the operators received electric shocks. Geomagnetic storms affect also long-haul telephone lines, including undersea cables if they aren’t fiber optic based.[3]

Ionospheric storms can also affect Macola’s Order Entry system causing customer numbers to not be saved with an order.

Navigation systems

Systems such as GPS, LORAN, and the now-defunct OMEGA are adversely affected when solar activity disrupts their signal propagation. The OMEGA system consisted of eight transmitters located throughout the world. Airplanes and ships used the very low frequency signals from these transmitters to determine their positions. During solar events and geomagnetic storms, the system gave navigators information that is inaccurate by as much as several miles. If navigators had been alerted that a proton event or geomagnetic storm is in progress, they could have switched to a backup system.

GPS signals are affected when solar activity causes sudden variations in the density of the ionosphere, causing the GPS signals to scintillate. The scintillation of satellite signals during ionospheric disturbances is studied at HAARP during ionospheric modification experiments. It has also been studied at the National Science Foundation equatorial ionospheric observation facility in Jicamarca, Peru.

Satellites

Geomagnetic storms and increased solar ultraviolet emission heat Earth’s upper atmosphere, causing it to expand. The heated air rises, and the density at the orbit of satellites up to about 1000 km increases significantly. This results in increased drag on satellites in space, causing them to slow and change orbit slightly. Unless Low Earth Orbit satellites are routinely boosted to higher orbits, they slowly fall, and eventually burn up in Earth’s atmosphere.

Skylab is an example of a spacecraft reentering Earth’s atmosphere prematurely in 1979 as a result of higher-than-expected solar activity. During the great geomagnetic storm of March 1989, four of the Navy’s navigational satellites had to be taken out of service for up to a week, the U.S. Space Command had to post new orbital elements for over 1000 objects affected, and the Solar Maximum Mission satellite was sent towards meeting the Skylab fate in December the same year.

The vulnerability of the satellites depends on their position as well. The South Atlantic Anomaly is a perilous place for a satellite to pass through.

As technology has allowed spacecraft components to become smaller, their miniaturized systems have become increasingly vulnerable to the more energetic solar particles. These particles can cause physical damage to microchips and can change software commands in satellite-borne computers.

Differential charging

Another problem for satellite operators is differential charging. During geomagnetic storms, the number and energy of electrons and ions increase. When a satellite travels through this energized environment, the charged particles striking the spacecraft cause different portions of the spacecraft to be differentially charged. Eventually, electrical discharges can arc across spacecraft components, harming and possibly disabling them.

Bulk charging

Bulk charging (also called deep charging) occurs when energetic particles, primarily electrons, penetrate the outer covering of a satellite and deposit their charge in its internal parts. If sufficient charge accumulates in any one component, it may attempt to neutralize by discharging to other components. This discharge is potentially hazardous to the satellite’s electronic systems.

Geologic exploration

Earth’s magnetic field is used by geologists to determine subterranean rock structures. For the most part, these geodetic surveyors are searching for oil, gas, or mineral deposits. They can accomplish this only when Earth’s field is quiet, so that true magnetic signatures can be detected. Other surveyors prefer to work during geomagnetic storms, when the variations to Earth’s normal subsurface electric currents help them to see subsurface oil or mineral structures. For these reasons, many surveyors use geomagnetic alerts and predictions to schedule their mapping activities.

Electric power

When magnetic fields move about in the vicinity of a conductor such as a wire, a geomagnetically induced current is produced into the conductor. This happens on a grand scale during geomagnetic storms (the same mechanism also influences telephone and telegraph lines, see above). Power companies transmit alternating current to their customers via long transmission lines. The nearly direct currents induced in these lines from geomagnetic storms are harmful to electrical transmission equipment, especially to the transformers—it overheats their coils and causes saturation of their cores, constraining their performance; it also tends to trip various protective devices. Potentially the heat generated in the iron cores of the generators can destroy them and chain reaction could blow transformers throughout a system[8][9]. On March 13, 1989, in Québec, 6 million people were without commercial electric power for 9 hours as a result of a huge geomagnetic storm. Some areas in the northeastern U.S. and in Sweden also lost power. By receiving geomagnetic storm alerts and warnings, power companies can minimize damage and power outages.

Worst case scenarios include Geomagnetic storm with the potential to damage power supply equipment world wide that would lead power blackouts of years while equipment was being replaced[10]. While this damage could be avoided this would require decision makers being willing to shut down the power system in advance[11].

Pipelines

Rapidly fluctuating geomagnetic fields can produce geomagnetically induced currents also into pipelines. During these times, several problems can arise for pipeline engineers. Flow meters in the pipeline can transmit erroneous flow information, and the corrosion rate of the pipeline is dramatically increased. If engineers unwittingly attempt to balance the current during a geomagnetic storm, corrosion rates may increase even more. Pipeline managers routinely receive alerts and warnings to help them provide an efficient and long-lived system.

Instruments

A wide range of ground based magneto spheric observations exist. Magnetometers monitor the auroral zone as well as the equatorial region. Two types of radar – coherent scatter and incoherent scatter – are used to probe the auroral ionosphere. By bouncing signals off ionospheric irregularities (which convect with their field lines) one can trace their motion and infer magnetospheric convection.

Spacecraft instruments include:

  • Magnetometers, usually of the flux gate type. Usually these are at the end of booms, to keep them away from magnetic interference by the spacecraft and its electric circuits.[12]
  • Electric sensors at the ends of opposing booms are used to measure potential differences between separated points, to derive electric field associated with convection. The methodworks best at high plasma densities in low Earth orbit; far from Earth long booms are needed, to avoid shielding-out of electric forces.
  • Radio sounders from the ground can bounce radio waves of varying frequency off the ionosphere, and by timing their return get the profile of electron density in the ionosphere – up to its peak, past which radio waves no longer return. Radio sounders in low Earth orbit aboard the Canadian Alouette (1962) and Alouette 2 (1965), beamed radio waves earthward and observed the electron density profile of the “topside ionosphere.” Other radio sounding methods were also tried in the ionosphere (e.g. on IMAGE).
  • A great variety of “particle detectors” has operated in orbit. The original observations of the Van Allen radiation belt used a Geiger counter, a crude detector unable to tell particle charge or energy. Later scintillator detectors were used, and still later “channeltron” electron multipliers have found particularly wide use. To derive charge and mass composition, as well as energies, a variety of mass spectrograph designs were used. For energies up to about 50 keV (which constitute most of the magnetospheric plasma) time-of-flight spectrometers (e.g. “top-hat” design) are widely used.
  • Computers are not usually viewed as scientific instruments, but they have been indispensable in magnetospheric research, and not just by pre-processing complex satellite data for more economical transmission of data to the ground. Computers have also made it possible to bring together decades of isolated magnetic observations and extract average patterns of electrical currents and average responses to interplanetary variations.

A different application are simulations of the global magnetosphere and its responses, by solving the equations of magnetohydrodynamics (MHD) on a numerical grid. Appropriate extensions must be added to cover the inner magnetosphere, where magnetic drifts and ionospheric conduction also need to be taken into account. So far the results are interesting, but their interpretation is not easy, and certain assumptions are still needed to cover small-scale phenomena.

Solar Storm Warning

03.10.2006

March 10, 2006: It’s official: Solar minimum has arrived. Sunspots have all but vanished. Solar flares are nonexistent. The sun is utterly quiet.

Like the quiet before a storm.

This week researchers announced that a storm is coming–the most intense solar maximum in fifty years. The prediction comes from a team led by Mausumi Dikpati of the National Center for Atmospheric Research (NCAR). “The next sunspot cycle will be 30% to 50% stronger than the previous one,” she says. If correct, the years ahead could produce a burst of solar activity second only to the historic Solar Max of 1958.

That was a solar maximum. The Space Age was just beginning: Sputnik was launched in Oct. 1957 and Explorer 1 (the first US satellite) in Jan. 1958. In 1958 you couldn’t tell that a solar storm was underway by looking at the bars on your cell phone; cell phones didn’t exist. Even so, people knew something big was happening when Northern Lights were sighted three times in Mexico. A similar maximum now would be noticed by its effect on cell phones, GPS, weather satellites and many other modern technologies.

Right: Intense auroras over Fairbanks, Alaska, in 1958. [More]

Dikpati’s prediction is unprecedented. In nearly-two centuries since the 11-year sunspot cycle was discovered, scientists have struggled to predict the size of future maxima—and failed. Solar maxima can be intense, as in 1958, or barely detectable, as in 1805, obeying no obvious pattern.

The key to the mystery, Dikpati realized years ago, is a conveyor belt on the sun.

We have something similar here on Earth—the Great Ocean Conveyor Belt, popularized in the sci-fi movie The Day After Tomorrow. It is a network of currents that carry water and heat from ocean to ocean–see the diagram below. In the movie, the Conveyor Belt stopped and threw the world’s weather into chaos.


Above: Earth’s “Great Ocean Conveyor Belt.” [More]

The sun’s conveyor belt is a current, not of water, but of electrically-conducting gas. It flows in a loop from the sun’s equator to the poles and back again. Just as the Great Ocean Conveyor Belt controls weather on Earth, this solar conveyor belt controls weather on the sun. Specifically, it controls the sunspot cycle.

Solar physicist David Hathaway of the National Space Science & Technology Center (NSSTC) explains: “First, remember what sunspots are–tangled knots of magnetism generated by the sun’s inner dynamo. A typical sunspot exists for just a few weeks. Then it decays, leaving behind a ‘corpse’ of weak magnetic fields.”

Enter the conveyor belt.

“The top of the conveyor belt skims the surface of the sun, sweeping up the magnetic fields of old, dead sunspots. The ‘corpses’ are dragged down at the poles to a depth of 200,000 km where the sun’s magnetic dynamo can amplify them. Once the corpses (magnetic knots) are reincarnated (amplified), they become buoyant and float back to the surface.” Presto—new sunspots!

Right: The sun’s “great conveyor belt.” [Larger image]

All this happens with massive slowness. “It takes about 40 years for the belt to complete one loop,” says Hathaway. The speed varies “anywhere from a 50-year pace (slow) to a 30-year pace (fast).”

When the belt is turning “fast,” it means that lots of magnetic fields are being swept up, and that a future sunspot cycle is going to be intense. This is a basis for forecasting: “The belt was turning fast in 1986-1996,” says Hathaway. “Old magnetic fields swept up then should re-appear as big sunspots in 2010-2011.”

Like most experts in the field, Hathaway has confidence in the conveyor belt model and agrees with Dikpati that the next solar maximum should be a doozy. But he disagrees with one point. Dikpati’s forecast puts Solar Max at 2012. Hathaway believes it will arrive sooner, in 2010 or 2011.

“History shows that big sunspot cycles ‘ramp up’ faster than small ones,” he says. “I expect to see the first sunspots of the next cycle appear in late 2006 or 2007—and Solar Max to be underway by 2010 or 2011.”

Who’s right? Time will tell. Either way, a storm is coming.

Solar Storm Warning

An interplanetary shock wave from a solar coronal mass ejection is expected to pass our planet this Thursday.

June 7, 2000 — Yesterday the orbiting Solar and Heliospheric Observatory (SOHO) recorded a powerful series of solar eruptions including a full-halo coronal mass ejection (CME).

“The halo CME was magnificent,” says Gary Heckman, a space weather forecaster at the NOAA Space Environment Center. “Based on [the characteristics of the eruption], this looks like a sure bet to produce a geomagnetic storm.”

The velocity of the ejected material was at least 908 km/s, says Dr. Simon Plunkett, an operations scientist with the SOHO coronagraph team at the Naval Research Laboratory and the Goddard Space Flight Center. “The CME should reach Earth in a little less than 48 hours. This would put its arrival around midday on Thursday, June 8.”

Above: This frame from a 350 kb animation shows a coronal mass ejection billowing away from the Sun on June 6, 2000. The solid-colored blue disk in the middle is an occulting disk that blocks out the Sun’s intense light to reveal the faint corona, along with background stars and planets. The white circle shows the true size of Sun. These images were captured by the wide field coronagraph on board the orbiting ESA/NASA Solar and Heliospheric Observatory.

Coronal mass ejections can carry up to 10 billion tons of electrified gas traveling at speeds as high as 2000 km/s. “Halo events” are CMEs aimed toward the Earth. As they loom larger and larger they appear to envelop the Sun, forming a halo around our star.

They may sound menacing, but CMEs pose little danger to people on Earth. Our planet’s magnetic field serves as an effective shield against solar wind storms. The same familiar force that causes compass needles on Earth to point north also extends far into space. When a CME hits the magnetosphere — the region around Earth controlled by its magnetic field — most of the incoming material is deflected away from our planet.

If a gust of solar wind is very strong — as this one might be — it can compress the magnetosphere and unleash a geomagnetic storm. In extreme cases, such storms can induce electric currents in the Earth that interfere with electric power transmission equipment. Satellite failures are possible, too. Geomagnetic storms can also trigger beautiful aurorae. These “Northern Lights” are usually seen at high latitudes, but they have been spotted farther south than Florida during intense disturbances. The last time this happened was April 6, 2000.

Left: This rare red-colored aurora over North Carolina was photographed by Chuck Adams on April 6, 2000. The bright object near the horizon is the Moon. Also visible in the background are the Pleiades, Taurus, and Orion. The photographer used a Nikon FM2 camera equipped with a 28mm f/2 lens. The exposure time was one minute on Kodak Elite 100 slide film. (Copyright 2000, Chuck Adams, all rights reserved.)

A Double Whammy

The June 6, 2000, coronal mass ejection was accompanied by two of the most intense solar flares since a brilliant eruption in February 2000.

“CMEs can occur without a flare,” says Dr. David Hathaway, a solar physicist at the Marshall Space Flight Center, “but today is the more typical case where a flare is also part of the eruption.

“Solar flares and CMEs occur whenever there’s a rapid, large-scale change in the Sun’s magnetic field. The solar active region that produced the eruptions [on June 6] had a complicated magnetic configuration – oppositely directed magnetic fields were seen right next to each other.”

Whenever space weather forecasters see a complex magnetic field like the one exhibited by sunspot group 9026 (where yesterday’s eruptions occurred) they know that solar flares are likely. In fact, the NOAA Space Environment Center predicted a possible major flare from 9026 several days ago. The region has been producing mid-sized flares since it rotated into view over the eastern limb of the Sun on June 1.

Above: This short animation shows the first of two X-class solar flares erupting from sunspot group 9026 at 13:36 UT on June 6, 2000. Click on the image for a more complete sequence. The images were recorded by SOHO’s Extreme Ultraviolet Telescope at 304 Angstroms. The full halo CME now heading for Earth appears to be associated with a second, more powerful flare that occurred one and a half hours later. Animations of that flare are available from the SOHO Extreme Ultraviolet Telescope at 195 Angstroms or as seen through a red Hydrogen-alpha filter (Holloman AFB). Right: This SOHO MDI white light image of the Sun shows the location of sunspot group 9026 on June 7, 2000.

Does this spate of solar activity means that Solar Maximum has finally arrived?

“This is an indication that solar maximum is upon us,” says Hathaway. There is a common misconception that “Solar Max” is a single episode of high activity. Not so, Hathaway cautions. The solar maximum will last over an extended period of time, perhaps as long as two years interspersed with many powerful solar flares and CMEs.

Waiting and Watching

When the CME arrives, scientists aren’t sure how big the geomagnetic storm will be.

“To get an intense geomagnetic storm from a CME we believe that two things must happen,” says Dr. James Spann of the Marshall Space Flight Center, a co-investigator on an ultraviolet imaging camera in orbit aboard NASA’s aurora-monitoring Polar satellite. “First, the disturbance must encounter the Earth’s magnetic field directly, as opposed to a glancing blow. Second, the magnetosphere must already have stored energy, ready to be released in the form of aurora. If either of these two conditions fail, we’re not likely to have an intense auroral display.”

Left: Click on the image to see what happens when a coronal mass ejection strikes our planet’s magnetosphere.

While no one is certain what will happen on the night of June 8, this is a rare opportunity to anticipate an auroral storm with two full days of advance warning. There’s plenty of time to set up your camera and prepare late-night observing snacks. You may need a cup of coffee, because the best time to spot aurora borealis is usually during the hours around local midnight (in this case, around the 12 o’clock boundary between June 8 and 9). The Moon will be in a waxing quarter phase, sinking below the horizon at approximately 1:30 a.m. local time on June 9. That will afford dark skies between moonset and dawn for rural observers at mid-latitudes. Unfortunately for sky watchers at higher latitudes (where aurora sightings are usually best), the extended hours of twilight just two weeks before the summer solstice may obscure all but the most intense Northern Lights.

The Science@NASA April 6th, 2000, aurora gallery features a selection of photos with camera settings suitable for recording aurora borealis. More observing tips are available at Jan Curtis’s web site “Home of the Northern Lights.”

The View from Space

A fleet of NASA and NOAA satellites will be monitoring events in space when the CME disturbance arrives tomorrow. These include Polar, GEOTAIL, ACE, POES and others.

Researchers say that the timing of this event couldn’t be better for NASA’s newest space mission — the Imager for Magnetopause to Aurora Global Exploration (IMAGE) — a unique satellite dedicated to the study of space storms. IMAGE’s ‘first light’ pictures of electrified gas in Earth’s magnetosphere were released just this week.

“We’ve been waiting for just such an event,” says NASA/Marshall’s Dr. Dennis Gallagher, a co-investigator on the IMAGE mission. “Hopefully, IMAGE will be in the right place in its orbit at the right time to see the start of any resulting storm in the Earth’s magnetosphere.”

Right: This sequence of pictures captured by the Ultraviolet Imager on NASA’s Earth-orbiting Polar satellite shows an auroral storm over northern Asia on February 24, 2000. Because it records ultraviolet light, Polar’s UV camera can see aurora from space on both the day and night sides of Earth. Polar is one of several missions operating as part of the International Solar Terrestrial Physics (ISTP) program. ISTP and IMAGE complement and support one another.

“Before IMAGE, if we wanted to understand what happened during a storm like the one that’s coming, we had to combine thousands of point-by-point measurements taken by different satellites during many distinct storms,” continued Gallagher. “No single satellite had a continuous, global view of all the action.

“It would be like trying to understand the rules of major league baseball if you were only allowed to watch a few random moments of different games while wearing blinders that only let you see a little bit of the field at once — like the first base line or right field — but nothing else. If you watched several different baseball fields in this way over many years, you might eventually start to put together what baseball is all about, but it would be very difficult. Now imagine what you can learn about the game if you were suddenly given sight and could see the whole field at once throughout every game.

“That’s how it is with IMAGE and the magnetosphere. We can see the whole thing at once for the first time. I hate to take advantage of this comparison, but with IMAGE it’s a whole new ball game!”

Stay tuned to Science@NASA for news and updates about the coming geomagnetic disturbance.

Below: Solar Flares are classified by their x-ray flux in the 1.0 – 8.0 Angstrom band as measured by the NOAA GOES-8 satellite. On June 6, 2000, two solar flares from active region 9026 registered as powerful X-class eruptions.

SOHO is a cooperative project between the European Space Agency (ESA) and NASA. The spacecraft was built in Europe for ESA and equipped with instruments by teams of scientists in Europe and the USA.

Southwest Research Institute manages the IMAGE project and leads the IMAGE science investigation. The IMAGE Principal Investigator is James L. Burch.

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