Earth's Magnetic Field Won't Flip Soon
If you're looking for a global catastrophe to have nightmares about, forget about a magnetic field crash. Continue reading →
This is going to come as a disturbing development, at least to those who believe that an upcoming reversal of the Earth's magnetic field - accompanied by the North and South poles flipping in polarity - is going to signal the onset of the End Times, as prophesied in either some ancient Maya hieroglyphic text or a Black Sabbath song played backwards.
As it turns out, in an article just published in Proceedings of the National Academy of Sciences, researchers from Massachusetts Institute of Technology and Rutgers University report that the Earth is NOT heading toward an imminent doomsday magnetic shift.
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The researchers report the Earth's magnetic field has been weakening over the past 200 years, which some have interpreted as a sign of an impending temporary bottoming-out. That could result in all sorts of bad stuff happening, since the magnetic field plays an important role in shielding us from excessive solar radiation. With a too-weak field, we might see a surge in genetic mutations, It could also wreak havoc upon migratory species such as monarch butterflies, which use the magnetic field as a guide in navigation.
Fortunately, though, that's not happening any time soon. As an MIT press release details, the researchers calculated Earth's average, stable field intensity over the last 5 million years, and found that today's intensity is about twice that of the historical average.
That means that the field's intensity would have to drop a lot more before it became unstable enough to cause a reversal.
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"It makes a huge difference, knowing if today's field is a long-term average or is way above the long-term average," says lead author Huapei Wang, a postdoctoral researcher in MIT's Department of Earth, Atmospheric and Planetary Sciences, said in the press release. "Now we know we are way above the unstable zone. Even if the (field intensity) is dropping, we still have a long buffer that we can comfortably rely on."
If it's any consolation to doomsday cultists, though, Wang did note that the Earth last had a magnetic field flip 780,000 years ago, "so we are actually overdue for a flip."
‘Snapshot’ of the main magnetic field at Earth’s surface as of June 2014, based on satellite data. Red areas have the highest strength, while blue areas are the weakest.
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.