Earth's Magnetic Shield Buffered Powerful Solar Storm

A giant eruption from the sun that scientists thought would hit Earth in 2014 missed because the sun's magnetic field channeled it away from the planet in an unexpected way, researchers say.

This finding could lead to better modeling and forecasting of disruptive solar storms in the future, the scientists added.

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Solar eruptions, known as coronal mass ejections, are the hurricanes of space weather. These explosions can drive on the order of a billion tons of super-hot matter out from the sun. [Solar Storm Photos of 2015]

When coronal mass ejections hit Earth, they can trigger major disturbances known as geomagnetic storms, which can in turn wreak massive havoc. For example, in 1989, a coronal mass ejection blacked out the entire Canadian province of Quebec within seconds, damaging transformers as far away as New Jersey, and nearly shutting down U.S. power grids from the mid-Atlantic through the Pacific Northwest.

To forecast the hazards that coronal mass ejections might pose to assets both on the ground and in space, researchers need to know where they are headed. However, much remains unknown about what guides their direction, and therefore whether they might hit Earth.

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For instance, on Jan. 7, 2014, astronomers spotted a very fast coronal mass ejection headed toward Earth, one traveling more than 5.3 million mph (8.6 million km/h). Scientists expected it would trigger a strong geomagnetic storm, one that could spark radio navigation problems and set off alarms in power systems. However, the worst of the eruption missed Earth, and no geomagnetic storm followed.

To learn more about why this coronal mass ejection missed Earth, scientists collected data from 7 different space missions that saw the explosion. They modeled the evolution of the eruption from the sun, up to Earth, and as far as Mars, where it was detected by the Curiosity rover.

Instead of hitting Earth, the coronal mass ejection was slanted toward a zone below and behind Earth. The researchers suggest it got channeled this way by powerful magnetic fields originating from a region nearby on the sun.

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"Very fast and possibly havoc-creating coronal mass ejections can erupt in a very different direction than indicated by the position of their source region on the sun,"study lead author Christian Möstl, a heliophysicist at the Austrian Academy of Sciences in Graz, told Space.com.

Potential applications of this research include better real-time predictions of space weather. "Forecasters should always look at the magnetic fields of the solar corona surrounding a big eruption to see how likely such a strongly channeled eruption is," Möstl said.

One problem with space weather forecasts is that even if scientists can figure out whether a coronal mass ejection is headed toward Earth, they cannot tell how powerful it is until it hits the planet.

"This is like not knowing the magnitude of a hurricane just before it hits the shore," Möstl said. "This is a situation that clearly must be improved."

The scientists detailed their findings online Tuesday (May 26) in the journal Nature Communications.

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Photos: Sunspots on Earth's Closest Star Original article on Space.com. Copyright 2015 SPACE.com, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

On Jan. 7, 2014, the sun unleashed a major solar flare and coronal mass ejection (the bright spot at center right), but the Earth's magnetic field channeled the worst of the solar storm away from the planet, scientists say.

The sun may be an average star when compared to the menagerie of stars that exist in our galaxy, but to Earth and all life on our planet, the sun is the most important object in the Universe. However, regardless of its importance and close proximity, our nearest star holds many mysteries that continue to fox solar physicists after decades of modern studies with cutting-edge observatories. One of the biggest mysteries surrounding the sun is the underlying mechanisms that drive solar flares and coronal mass ejections (CMEs). Monday evening (EST), the sun reminded us that it hasn't quite finished with the current solar maximum (of solar cycle 24), unleashing a powerful X4.9 solar flare -- the biggest of 2014. An armada of space telescopes witnessed the event, including NASA's Solar Dynamics Observatory that can spy the sun's temper tantrums in astounding high definition. Shown here, 5 of the 10 filters from the SDO's Atmospheric Imaging Assembly (AIA) instrument are featured, showing the sun's lower corona (the solar multimillion degree atmosphere) through 5 wavelengths; each wavelength of extreme ultraviolet light representing a different plasma temperature and key coronal features -- such as coronal loops (highlighted here in the 'yellow' 171A filter) and ejected plasma that formed a CME.

At 7:13 p.m. EST (00:13 UT, Feb. 25) -- pictured here on the far left -- the active region (AR) 1990 was crackling with activity. Then, as magnetic field lines from the sun's interior forced together and through the solar photosphere, large-scale reconnection events occurred. Reconnection is a magnetic phenomena where field lines "snap" and reconnect, releasing huge quantities of energy in the process. At 7:44 p.m. EST (00:44 UT) -- second frame from the right -- a kinked coronal loop can be seen rising into the corona. At 7:59 p.m. EST (00:59 UT) -- far right -- solar plasma contained within the magnetic flux is accelerated to high energy, generating powerful x-rays and extreme ultraviolet radiation, creating the X-class flare.

The X4.9 flare was caught through the range of SDO fliters, including this dramatic view as seen through the 131A filter. The flare was so bright that photons from the flare overloaded the SDO's CCD inside the AIA instrument, causing the signal to "bleed" across the pixels. This bleeding effect is common for any optical instrument observing powerful solar flares.

Intense coronal activity is often associated with active regions -- the active lower corona is pictured here, left. In this case, the flare erupted from AR1990, at the limb of the sun. Also associated with active regions are sunspots, dark patches observed in the sun's photosphere (colloquially known as the sun's "surface") -- pictured right. The sun's cooler photosphere has been imaged by a different SDO instrument called Helioseismic and Magnetic Imager (HMI), which detects the intensity of magnetic fields threading though the sun's lower corona and photosphere.

In the case of AR1990, a large sunspot can be seen at the base of the coronal loops that erupted to generate the powerful flare. This is a prime example of how sunspots can be used to gauge solar activity and how they are often found at the base of intense coronal activity and flares.

The HMI monitors magnetic activity across the disk of the sun and can also generate a picture on the direction of the magnetic field polarity. In this observation of the sun's magnetic field around the time of the recent X-class flare, other active regions can be easily seen -- intense white and black regions highlighting where magnetic field lines emerge and sink back into the sun's interior in active regions.

The joint NASA/ESA Solar and Heliospheric Observatory (SOHO), which has been watching the sun since 1996, also spotted the flare, tracking a CME that was generated shortly after. Seen here by SOHO's LASCO C2 instrument, that monitors the interplanetary environment surrounding the sun for CMEs and comets, a growing bubble of solar plasma races away from the sun.

Approximately an hour after the flare, the CME grew and continued to barrel into interplanetary space. Space weather forecasters don't expect that this CME will interact with the Earth's atmosphere as it is not Earth-directed. This observation was captured by SOHO's LASCO C3 instrument -- an occulting disk covers the sun to block out any glaring effect. By combining observations by the SDO, SOHO and other solar observatories, the connection between the sun's internal magnetic "dynamo", the solar cycle, flares and CMEs, solar physicists are slowly piecing together what makes our nearest star tick, hopefully solving some of the most persistent mysteries along the way.