It's official;
The New Cosmic Age has arrived!

NASA & European Space Agency
Space Weather News

June 4, 2010: Earth and space are about to come into contact in a way that's new to human history. To make preparations, authorities in Washington DC are holding a meeting: The Space Weather Enterprise Forum at the National Press Club on June 8th.

Richard Fisher, head of NASA's Heliophysics Division, explains what it's all about:

"The sun is waking up from a deep slumber, and in the next few years we expect to see much higher levels of solar activity. At the same time, our technological society has developed an unprecedented sensitivity to solar storms. The intersection of these two issues is what we're getting together to discuss."

The National Academy of Sciences framed the problem two years ago in a landmark report entitled "Severe Space Weather Events—Societal and Economic Impacts." It noted how people of the 21st-century rely on high-tech systems for the basics of daily life. Smart power grids, GPS navigation, air travel, financial services and emergency radio communications can all be knocked out by intense solar activity. A century-class solar storm, the Academy warned, could cause twenty times more economic damage than Hurricane Katrina.

Much of the damage can be mitigated if managers know a storm is coming. Putting satellites in 'safe mode' and disconnecting transformers can protect these assets from damaging electrical surges. Preventative action, however, requires accurate forecasting—a job that has been assigned to NOAA.

"Space weather forecasting is still in its infancy, but we're making rapid progress," says Thomas Bogdan, director of NOAA's Space Weather Prediction Center in Boulder, Colorado.

Bogdan sees the collaboration between NASA and NOAA as key. "NASA's fleet of heliophysics research spacecraft provides us with up-to-the-minute information about what's happening on the sun. They are an important complement to our own GOES and POES satellites, which focus more on the near-Earth environment."

NASA spacecraft were not originally intended for operational forecasting—"but it turns out that our data have practical economic and civil uses," notes Fisher. "This is a good example of space science supporting modern society."

2010 marks the 4th year in a row that policymakers, researchers, legislators and reporters have gathered in Washington DC to share ideas about space weather. This year, forum organizers plan to sharpen the focus on critical infrastructure protection. The ultimate goal is to improve the nation’s ability to prepare, mitigate, and respond to potentially devastating space weather events.

"I believe we're on the threshold of a new era in which space weather can be as influential in our daily lives as ordinary terrestrial weather." Fisher concludes. "We take this very seriously indeed."

Author: Dr. Tony Phillips | Credit: Science@NASA

On 7 November 2004, the Sun blasted a solar storm in Earth’s direction. It was composed of an interplanetary shock wave followed by a large magnetic cloud. When the shock wave first swept over the ESA-NASA solar watchdog satellite SOHO, the speed of the solar wind (the constant flow of solar particles) suddenly increased from 500 km/s to 700 km/s. Shortly afterwards, the shock wave hit Earth’s protective magnetic bubble, known as the magnetosphere. The impact induced a wave front propagating inside the magnetosphere at more than 1200 km/s at geostationary orbit (36 000 km altitude) around Earth. The quantity of energetic electrons in the outer radiation belt started to increase too, according to Cluster’s RAPID instruments (Research with Adaptive Particle Imaging Detectors). Cluster’s four satellites sweep around an elliptical orbit, coming as close as 19 000 km and going out as far as 119 000 km.

Understanding the origin of the killer electrons has been a focus for space weather researchers. Thanks to previous data collected by Cluster and other space missions, scientists proposed two methods by which electrons can be accelerated to such harmful energy levels. One relies on very low frequency (VLF) waves of 3–30 kHz, the other on ultra low frequency (ULF) waves of 0.001–1 Hz. This latest work disentangles the problem.
[...]

Thanks to this analysis of Cluster data, if the killer electrons happen to be ejected towards Earth, we now know that they can strike the atmosphere within just 15 minutes. “These new findings help us to improve the models predicting the radiation environment in which satellites and astronauts operate. With solar activity now ramping up, we expect more of these shocks to impact our magnetosphere over the months and years to come,” says Philippe Escoubet, ESA’s Cluster mission manager.

Airline passengers could be exposed to 400 chest X-rays worth of radiation

Instruments scanning outer space for cataclysmic explosions called gamma-ray bursts are detecting intense flashes of gamma-ray energy right here in the friendly skies of Earth. These terrestrial gamma-ray flashes, or TGFs, blast through thunderstorms close to the altitude where commercial airliners fly.

In fact, they could be too close for comfort.

In a recent study,* scientists estimated that airline passengers could be exposed to 400 chest X-rays worth of radiation by being near the origin of a single millisecond blast. Joe Dwyer of the Florida Institute of Technology took part in that research, which used observations from NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager, or RHESSI, to estimate the danger TGFs pose.

"We believe the risk of encountering a TGF in an airplane is very small," says Dwyer. "I wouldn't hesitate to take a flight. Pilots already avoid thunderstorms because of turbulence, hail, and lightning, and we may just have to add TGFs to the list of reasons to steer clear of those storms."

But, he stresses, "it's worth looking into."

NASA's Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Telescope will help evaluate the hazards.

"GBM provides the best TGF data we have so far," says Dwyer. "It gets better measurements of their spectra than any previous instrument, giving us a more accurate idea of just how energetic they are."

Although TGFs are quite brief (1-2 milliseconds), they appear to be the most energetic events on Earth. They belch destructive gamma-rays packing over ten million times the energy of visible light photons – enough punch to penetrate several inches of lead.

"It's amazing," says Jerry Fishman, a co-investigator for the Gamma-ray Burst Monitor. "They come blasting right through the whole Fermi spacecraft and light up all of our detectors. Very few cosmic gamma-ray bursts manage to do this!"

The origin of TGFs is still a mystery, but researchers know this much: TGFs are associated with thunderstorms and lightning. "We think the electric field in a thunderstorm may get so strong that the storm itself turns into a gamma-ray factory," says Dwyer. "But we don't know exactly how or why or where inside the storm this happens."

So no one yet knows how often, if ever, planes end up in the wrong place at the wrong time.

[...] "TGFs have really been an afterthought for missions so far," says Dwyer. RHESSI, for example, points at the sun, but the RHESSI team figured out a way to measure TGFs by detecting gamma-rays coming in through the satellite's backside. "All these instruments have been pointing across the universe, while right over our heads these monsters are going off!"

"Now the whole field of TGFs is on fire," says Fishman. "People are jumping on the bandwagon to try to figure them out."

The Earth's magnetic field protects our planet from most of the permanent flow of particles from the solar wind. Fissures in this magnetic shield are known to occur, enabling the solar wind to penetrate our near-space environment. A study based on data collected by the four ESA Cluster satellites and the CNSA/ESA Double Star TC-1 spacecraft, provides new insight into the location and duration of these ruptures in the Earth's magnetic shield.

This study reports the observation of fissures on the Sun-facing side of the Earth's magnetic shield – the dayside magnetopause.

Fortunately, these fissures don't expose Earth's surface to the solar wind; our atmosphere protects us, even when our magnetic field doesn't.

However, clear effects have been detected high in the upper atmosphere and in the region of space around Earth where satellites orbit.

Last year, when NASA's IBEX (Interstellar Boundary Explorer) spacecraft discovered a giant ribbon at the edge of the solar system, researchers were mystified. They called it a "shocking result" and puzzled over its origin. Now the mystery may have been solved.

Heerikhuisen is the lead author of a paper reporting the results in the Jan. 10th edition of the Astrophysical Journal Letters.

"This is an important finding," says Arik Posner, IBEX program scientist at NASA Headquarters. "Interstellar space just beyond the edge of the solar system is mostly unexplored territory. Now we know, there could be a strong, well-organized magnetic field sitting right on our doorstep."

The IBEX data fit in nicely with recent results from Voyager. Voyager 1 and 2 are near the edge of the solar system and they also have sensed strong* magnetism nearby. Voyager measurements are relatively local to the spacecraft, however. IBEX is filling in the "big picture." The ribbon it sees is vast and stretches almost all the way across the sky, suggesting that the magnetic field behind it must be equally vast.

Although maps of the ribbon (see below) seem to show a luminous body, the ribbon emits no light. Instead, it makes itself known via particles called "energetic neutral atoms" (ENAs)--mainly garden-variety hydrogen atoms. The ribbon emits these particles, which are picked up by IBEX in Earth orbit.

Above: A comparison of IBEX observations (left) with a 3D magnetic reflection model (right). More images: data, model.

The reflection process posited by Heerikhuisen et al. is a bit complicated, involving multiple "charge exchange" reactions between protons and hydrogen atoms. The upshot, however, is simple. Particles from the solar wind that escape the solar system are met ~100 astronomical units (~15 billion kilometers) away by an interstellar magnetic field. Magnetic forces intercept the escaping particles and sling them right back where they came from.

"If this mechanism is correct--and not everyone agrees--then the shape of the ribbon is telling us a lot about the orientation of the magnetic field in our corner of the Milky Way galaxy," notes Heerikhuisen.

And upon this field, the future may hinge.

The solar system is passing through a region of the Milky Way filled with cosmic rays and interstellar clouds. The magnetic field of our own sun, inflated by the solar wind into a bubble called the "heliosphere," substantially protects us from these things. However, the bubble itself is vulnerable to external fields. A strong magnetic field just outside the solar system could press against the heliosphere and interact with it in unknown ways. Will this strengthen our natural shielding—or weaken it? No one can say.

Right: An artist's concept of interstellar clouds in the galactic neighborhood of the sun. [more]

"IBEX will monitor the ribbon closely in the months and years ahead," says Posner. "We could see the shape of the ribbon change—and that would show us how we are interacting with the galaxy beyond."

It seems we can learn a lot by looking in the mirror. Stay tuned to Science@NASA for updates.

The solar system is passing through an interstellar cloud that physics says should not exist. In the Dec. 24th issue of Nature, a team of scientists reveal how NASA's Voyager spacecraft have solved the mystery.

The discovery has implications for the future when the solar system will eventually bump into other, similar clouds in our arm of the Milky Way galaxy.

Astronomers call the cloud we're running into now the Local Interstellar Cloud or "Local Fluff" for short. It's about 30 light years wide and contains a wispy mixture of hydrogen and helium atoms at a temperature of 6000 C. The existential mystery of the Fluff has to do with its surroundings. About 10 million years ago, a cluster of supernovas exploded nearby, creating a giant bubble of million-degree gas. The Fluff is completely surrounded by this high-pressure supernova exhaust and should be crushed or dispersed by it.

"The observed temperature and density of the local cloud do not provide enough pressure to resist the 'crushing action' of the hot gas around it," says Opher.

So how does the Fluff survive? The Voyagers have found an answer.

"Voyager data show that the Fluff is much more strongly magnetized than anyone had previously suspected—between 4 and 5 microgauss^*," says Opher. "This magnetic field can provide the extra pressure required to resist destruction."

An artist's concept of the Local Interstellar Cloud, also known as the "Local Fluff." Credit: Linda Huff (American Scientist) and Priscilla Frisch (University of Chicago)

NASA's two Voyager probes have been racing out of the solar system for more than 30 years. They are now beyond the orbit of Pluto and on the verge of entering interstellar space—but they are not there yet.

"The Voyagers are not actually inside the Local Fluff," says Opher. "But they are getting close and can sense what the cloud is like as they approach it."

The Fluff is held at bay just beyond the edge of the solar system by the sun's magnetic field, which is inflated by solar wind into a magnetic bubble more than 10 billion km wide. Called the "heliosphere," this bubble acts as a shield that helps protect the inner solar system from galactic cosmic rays and interstellar clouds. The two Voyagers are located in the outermost layer of the heliosphere, or "heliosheath," where the solar wind is slowed by the pressure of interstellar gas.

Voyager 1 entered the heliosheath in Dec. 2004; Voyager 2 followed almost 3 years later in Aug. 2007. These crossings were key to Opher et al's discovery.

The size of the heliosphere is determined by a balance of forces: Solar wind inflates the bubble from the inside while the Local Fluff compresses it from the outside. Voyager's crossings into the heliosheath revealed the approximate size of the heliosphere and, thus, how much pressure the Local Fluff exerts. A portion of that pressure is magnetic and corresponds to the ~5 microgauss Opher's team has reported in Nature.

The fact that the Fluff is strongly magnetized means that other clouds in the galactic neighborhood could be, too. Eventually, the solar system will run into some of them, and their strong magnetic fields could compress the heliosphere even more than it is compressed now. Additional compression could allow more cosmic rays to reach the inner solar system, possibly affecting terrestrial climate and the ability of astronauts to travel safely through space. On the other hand, astronauts wouldn't have to travel so far because interstellar space would be closer than ever. These events would play out on time scales of tens to hundreds of thousands of years, which is how long it takes for the solar system to move from one cloud to the next.

NASA News, 28th September 2009

Energetic iron nuclei counted by the Cosmic Ray Isotope Spectrometer on NASA's Advanced Composition Explorer (ACE) spacecraft eveal that cosmic ray levels have jumped 19% above the previous Space Age high. Credit: Richard Mewaldt/Caltech. Full size image here.

Planning a trip to Mars? Take plenty of shielding. According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high.

"In 2009, cosmic ray intensities have increased 19% beyond anything we've seen in the past 50 years," says Richard Mewaldt of Caltech. "The increase is significant, and it could mean we need to re-think how much radiation shielding astronauts take with them on deep-space missions."

The cause of the surge is solar minimum, a deep lull in solar activity that began around 2007 and continues today. Researchers have long known that cosmic rays go up when solar activity goes down. Right now solar activity is as weak as it has been in modern times, setting the stage for what Mewaldt calls "a perfect storm of cosmic rays."

"We're experiencing the deepest solar minimum in nearly a century," says Dean Pesnell of the Goddard Space Flight Center, "so it is no surprise that cosmic rays are at record levels for the Space Age."

Galactic cosmic rays come from outside the solar system. They are subatomic particles--mainly protons but also some heavy nuclei--accelerated to almost light speed by distant supernova explosions. Cosmic rays cause "air showers" of secondary particles when they hit Earth's atmosphere; they pose a health hazard to astronauts; and a single cosmic ray can disable a satellite if it hits an unlucky integrated circuit.

An artist's concept of the heliosphere, a magnetic bubble that partially protects the solar system from cosmic rays. Credit: Walt Feimer/NASA GSFC's Conceptual Image Lab. Full size image here.

1. The sun's magnetic field is weak. "There has been a sharp decline in the sun's interplanetary magnetic field (IMF) down to only 4 nanoTesla (nT) from typical values of 6 to 8 nT," he says. "This record-low IMF undoubtedly contributes to the record-high cosmic ray fluxes."


2. The solar wind is flagging. "Measurements by the Ulysses spacecraft show that solar wind pressure is at a 50-year low," he continues, "so the magnetic bubble that protects the solar system is not being inflated as much as usual." A smaller bubble gives cosmic rays a shorter-shot into the solar system. Once a cosmic ray enters the solar system, it must "swim upstream" against the solar wind. Solar wind speeds have dropped to very low levels in 2008 and 2009, making it easier than usual for a cosmic ray to proceed.


The heliospheric current sheet is shaped like a ballerina's skirt. Credit: J. R. Jokipii, University of Arizona. Full size image here.

3. The current sheet is flattening. Imagine the sun wearing a ballerina's skirt as wide as the entire solar system with an electrical current flowing along the wavy folds. That is the "heliospheric current sheet," a vast transition zone where the polarity of the sun's magnetic field changes from plus (north) to minus (south). The current sheet is important because cosmic rays tend to be guided by its folds. Lately, the current sheet has been flattening itself out, allowing cosmic rays more direct access to the inner solar system.

Did you know a solar flare can make your toilet stop working?

That's the surprising conclusion of a NASA-funded study by the National Academy of Sciences entitled Severe Space Weather Events—Understanding Societal and Economic Impacts. In the 132-page report, experts detailed what might happen to our modern, high-tech society in the event of a "super solar flare" followed by an extreme geomagnetic storm. They found that almost nothing is immune from space weather —not even the water in your bathroom.

To estimate the scale of such a failure, report co-author John Kappenmann of the Metatech Corporation looked at the great geomagnetic storm of May 1921, which produced ground currents as much as ten times stronger than the 1989 Quebec storm, and modeled its effect on the modern power grid. He found more than 350 transformers at risk of permanent damage and 130 million people without power. The loss of electricity would ripple across the social infrastructure with "water distribution affected within several hours; perishable foods and medications lost in 12-24 hours; loss of heating/air conditioning, sewage disposal, phone service, fuel re-supply and so on."

"The concept of interdependency," the report notes, "is evident in the unavailability of water due to long-term outage of electric power--and the inability to restart an electric generator without water on site."

"A contemporary repetition of the Carrington Event would cause … extensive social and economic disruptions," the report warns. Power outages would be accompanied by radio blackouts and satellite malfunctions; telecommunications, GPS navigation, banking and finance, and transportation would all be affected. Some problems would correct themselves with the fading of the storm: radio and GPS transmissions could come back online fairly quickly. Other problems would be lasting: a burnt-out multi-ton transformer, for instance, can take weeks or months to repair. The total economic impact in the first year alone could reach $2 trillion, some 20 times greater than the costs of a Hurricane Katrina or, to use a timelier example, a few TARPs.

What's the solution? The report ends with a call for infrastructure designed to better withstand geomagnetic disturbances, improved GPS codes and frequencies, and improvements in space weather forecasting. Reliable forecasting is key. If utility and satellite operators know a storm is coming, they can take measures to reduce damage—e.g., disconnecting wires, shielding vulnerable electronics, powering down critical hardware. A few hours without power is better than a few weeks.

NASA has deployed a fleet of spacecraft to study the sun and its eruptions. The Solar and Heliospheric Observatory (SOHO), the twin STEREO probes, ACE, Wind and others are on duty 24/7. NASA physicists use data from these missions to understand the underlying physics of flares and geomagnetic storms; personnel at NOAA's Space Weather Prediction Center use the findings, in turn, to hone their forecasts.

At the moment, no one knows when the next super solar storm will erupt. It could be 100 years away or just 100 days. It's something to think about the next time you flush.

WASHINGTON -- A NASA-funded study describes how extreme solar eruptions could have severe consequences for communications, power grids and other technology on Earth.

The National Academy of Sciences in Washington conducted the study. The resulting report provides some of the first clear economic data that effectively quantifies today's risk of extreme conditions in space driven by magnetic activity on the sun and disturbances in the near-Earth environment. Instances of extreme space weather are rare and are categorized with other natural hazards that have a low frequency but high consequences.

"Obviously, the sun is Earth's life blood," said Richard Fisher, director of the Heliophysics division at NASA Headquarters in Washington. "To mitigate possible public safety issues, it is vital that we better understand extreme space weather events caused by the sun's activity."

Besides emitting a continuous stream of plasma called the solar wind, the sun periodically releases billions of tons of matter called coronal mass ejections. These immense clouds of material, when directed toward Earth, can cause large magnetic storms in the magnetosphere and upper atmosphere. Such space weather can affect the performance and reliability of space-borne and ground-based technological systems.

Space weather can produce solar storm electromagnetic fields that induce extreme currents in wires, disrupting power lines, causing wide-spread blackouts and affecting communication cables that support the Internet. Severe space weather also produces solar energetic particles and the dislocation of the Earth's radiation belts, which can damage satellites used for commercial communications, global positioning and weather forecasting. Space weather has been recognized as causing problems with new technology since the invention of the telegraph in the 19th century.

A catastrophic failure of commercial and government infrastructure in space and on the ground can be mitigated through raising public awareness, improving vulnerable infrastructure and developing advanced forecasting capabilities. Without preventive actions or plans, the trend of increased dependency on modern space-weather sensitive assets could make society more vulnerable in the future.

NASA requested the study to assess the potential damage from significant space weather during the next 20 years. National and international experts from industry, government and academia participated in the study. The report documents the possibility of a space weather event that has societal effects and causes damage similar to natural disasters on Earth.

"From a public policy perspective, it is quite significant that we have begun the extremely challenging task of assessing space weather impacts in a quantitative way," said Daniel Baker, professor and director of the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. Baker chaired the panel that prepared the report.

"Whether it is terrestrial catastrophes or extreme space weather incidents, the results can be devastating to modern societies that depend in a myriad of ways on advanced technological systems," said Baker. "We were delighted that NASA helped support bringing together dozens of world experts from industry and government to share their experiences and begin planning of improved public policy strategies."

Above: A computer model of solar wind flowing around Earth's magnetic field on June 3, 2007. Background colors represent solar wind density; red is high density, blue is low. Solid black lines trace the outer boundaries of Earth's magnetic field. Note the layer of relatively dense material beneath the tips of the white arrows; that is solar wind entering Earth's magnetic field through the breach. Credit: Jimmy Raeder/UNH. Full size image here.

NASA's five THEMIS spacecraft have discovered a breach in Earth's magnetic field ten times larger than anything previously thought to exist. Solar wind can flow in through the opening to "load up" the magnetosphere for powerful geomagnetic storms. But the breach itself is not the biggest surprise. Researchers are even more amazed at the strange and unexpected way it forms, overturning long-held ideas of space physics.

"At first I didn't believe it," says THEMIS project scientist David Sibeck of the Goddard Space Flight Center. "This finding fundamentally alters our understanding of the solar wind-magnetosphere interaction."

The magnetosphere is a bubble of magnetism that surrounds Earth and protects us from solar wind. Exploring the bubble is a key goal of the THEMIS mission, launched in February 2007. The big discovery came on June 3, 2007, when the five probes serendipitously flew through the breach just as it was opening. Onboard sensors recorded a torrent of solar wind particles streaming into the magnetosphere, signaling an event of unexpected size and importance.

"The opening was huge—four times wider than Earth itself," says Wenhui Li, a space physicist at the University of New Hampshire who has been analyzing the data. Li's colleague Jimmy Raeder, also of New Hampshire, says "10²⁷ particles per second were flowing into the magnetosphere—that's a 1 followed by 27 zeros. This kind of influx is an order of magnitude greater than what we thought was possible."

The years ahead could be especially lively. Raeder explains: "We're entering Solar Cycle 24. For reasons not fully understood, CMEs in even-numbered solar cycles (like 24) tend to hit Earth with a leading edge that is magnetized north. Such a CME should open a breach and load the magnetosphere with plasma just before the storm gets underway. It's the perfect sequence for a really big event."

Sibeck agrees. "This could result in stronger geomagnetic storms than we have seen in many years."

The height of the ionosphere/space transition is controlled in part by the amount of extreme ultraviolet energy emitted by the Sun and a somewhat contracted ionosphere could have been expected because C/NOFS was launched during a minimum in the 11-year cycle of solar activity. However, the size of the actual contraction caught investigators by surprise. (Credit: NASA/Goddard Space Flight Center) Full size image here.

Observations made by NASA instruments onboard an Air Force satellite have shown that the boundary between the Earth's upper atmosphere and space has moved to extraordinarily low altitudes. These observations were made by the Coupled Ion Neutral Dynamics Investigation (CINDI) instrument suite, which was launched aboard the U.S. Air Force's Communication/Navigation Outage Forecast System (C/NOFS) satellite on April 16, 2008.

CINDI's first discovery was, however, that the ionosphere was not where it had been expected to be. During the first months of CINDI operations the transition between the ionosphere and space was found to be at about 260 miles (420 km) altitude during the nighttime, barely rising above 500 miles (800 km) during the day. These altitudes were extraordinarily low compared with the more typical values of 400 miles (640 km) during the nighttime and 600 miles (960 km) during the day.

The height of the ionosphere/space transition is controlled in part by the amount of extreme ultraviolet energy emitted by the Sun and a somewhat contracted ionosphere could have been expected because C/NOFS was launched during a minimum in the 11-year cycle of solar activity. However, the size of the actual contraction caught investigators by surprise. In fact, when they looked back over records of solar activity, they found that C/NOFS had been launched during the quietest solar minimum since the space age began.

This extraordinary circumstance is providing an unparalleled opportunity to study the connection between the interior dynamics of the Sun and the response of the Earth's space environment.

Sept. 23, 2008: In a briefing today at NASA headquarters, solar physicists announced that the solar wind is losing power.

"The average pressure of the solar wind has dropped more than 20% since the mid-1990s," says Dave McComas of the Southwest Research Institute in San Antonio, Texas. "This is the weakest it's been since we began monitoring solar wind almost 50 years ago." [...]

Curiously, the speed of the million mph solar wind hasn't decreased much—only 3%. The change in pressure comes mainly from reductions in temperature and density. The solar wind is 13% cooler and 20% less dense.

"What we're seeing is a long term trend, a steady decrease in pressure that began sometime in the mid-1990s," explains Arik Posner, NASA's Ulysses Program Scientist in Washington DC.

How unusual is this event?

"It's hard to say. We've only been monitoring solar wind since the early years of the Space Age—from the early 60s to the present," says Posner. "Over that period of time, it's unique. How the event stands out over centuries or millennia, however, is anybody's guess. We don't have data going back that far."

Flagging solar wind has repercussions across the entire solar system—beginning with the heliosphere.

The heliosphere is a bubble of magnetism springing from the sun and inflated to colossal proportions by the solar wind. Every planet from Mercury to Pluto and beyond is inside it. The heliosphere is our solar system's first line of defense against galactic cosmic rays. High-energy particles from black holes and supernovas try to enter the solar system, but most are deflected by the heliosphere's magnetic fields.

Right: The heliosphere. Click to view a larger image showing the rest of the bubble.

"The solar wind isn't inflating the heliosphere as much as it used to," says McComas. "That means less shielding against cosmic rays."

Flood of highly charged 'stardust' invades our solar system

Until ten years ago, most astronomers did not believe stardust could enter our Solar System. Then ESA's Ulysses spaceprobe discovered minute stardust particles leaking through the Sun's magnetic shield, into the realm of Earth and the other planets. Now, the same spaceprobe has shown that a flood of dusty particles is heading our way. Since its launch in 1990, Ulysses has constantly monitored how much stardust enters the Solar System from the interstellar space around it. Using an on-board instrument called DUST, scientists have discovered that stardust can actually approach the Earth and other planets, but its flow is governed by the Sun's magnetic field, which behaves as a powerful gate-keeper bouncing most of it back. However, during solar maximum - a phase of intense activity inside the Sun that marks the end of each 11-year solar cycle - the magnetic field becomes disordered as its polarity reverses. As a result, the Sun's shielding power weakens and more stardust can sneak in.

What is surprising in this new Ulysses discovery is that the amount of stardust has continued to increase even after the solar activity calmed down and the magnetic field resumed its ordered shape in 2001.

Scientists believe that this is due to the way in which the polarity changed during solar maximum. Instead of reversing completely, flipping north to south, the Sun's magnetic poles have only rotated at halfway and are now more or less lying sideways along the Sun's equator. This weaker configuration of the magnetic shield is letting in two to three times more stardust than at the end of the 1990s. Moreover, this influx could increase by as much as ten times until the end of the current solar cycle in 2012.

The stardust itself is very fine - just one-hundredth of the width of a human hair. It is unlikely to have much effect on the planets but it is bound to collide with asteroids, chipping off larger dust particles, again increasing the amount of dust in the inner Solar System. On the one hand, this means that the solar panels of spacecraft may be struck more frequently by dust, eventually causing a gradual loss of power, and that space observatories looking in the plane of the planets may have to cope with the haze of more sunlight diffused by the dust. [...]

Astronomers still do not know whether the current stardust influx, apart from being favoured by the particular configuration of the Sun's magnetic field, is also enhanced by the thickness of the interstellar clouds into which the Solar System is moving. Currently located at the edge of what astronomers call the local interstellar cloud, our Sun is about to join our closest stellar neighbour Alpha Centauri in its cloud, which is less hot but denser.

ESA's Ulysses data make it finally possible to study how stardust is distributed along the path of the Solar System through the local galactic environment. However, as it takes over 70 thousand years to traverse a typical galactic cloud, no abrupt changes are expected in the short term.

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