The sun erupted with one of the largest solar flares of this solar cycle
Autor: Blog Eliel Bragatti LiGEA USP 2004 | Publicado: 2012-03-10T01:39:00-03:00




Geomagnetic Storm Strength Increases

03.09.12



UPDATE 03/09/12




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An aurora on March 8, 2012 shimmering over snow-covered mountains  in 
Faskrudsfjordur, Iceland. Image courtesy of Jónína Óskarsdóttir



Geomagnetic storms due to coronal mass ejections (CMEs) earlier in the 
week have increased in strength, and are now rated a G3 on a scale from 
G1 to G5.

This space weather is due to the March 7 activity from the sun that 
caused rapid changes to the shape of Earth's magnetosphere – the bubble 
of protective magnetic fields surrounding the planet -- resulting in a 
geomagnetic storm.  As of March 8, the storm was fairly mild since the 
magnetic fields from the CMEs were partially aligned with Earth's own 
and thus slid around the magnetosphere.  However, the geomagnetic storm 
has increased because the magnetic fields of the CMEs have now changed 
direction such that they can more easily deposit magnetic energy and 
radiation into Earth's environment.



UPDATE 03/08/12
The leading edge of the March 6 coronal mass ejection (CME), reached 
NASA's Advanced Composition Explorer (ACE) satellite at 5:42 AM EST.  
ACE sits just outside of Earth's magnetic environment, the 
magnetosphere. As magnetic fields from the CMEs connected up to the 
magnetosphere, instruments on Earth began to measure changes in our 
planet's magnetic fields – indicating the onset of a geomagnetic storm. 
 At the time of writing this was still a minor storm, rated a G1 on a 
scale of G1 to G5.  There will be updates as needed if the rating 
increases.



UPDATE 03/07/12 2:30pm EST
NASA models using data from the Solar Terrestrial Relations Observatory 
(STEREO) and the Solar Heliospheric Observatory (SOHO) have now provided
 more information about the two CMEs associated with the two March 6 
flares.  The first is traveling faster than 1300 miles per second; the 
second more than 1100 miles per second.  NASA's models predict that the 
CMEs will impact both Earth and Mars, as well as pass by several NASA 
spacecraft – Messenger, Spitzer, and STEREO-B.  The models also predict 
that the leading edge of the first CME will reach Earth at about 1:25 AM
 EST on the morning of March 8 (plus or minus 7 hours). Such a CME could
 result in a severe geomagnetic storm, causing aurora at low latitudes, 
with possible disruption to high frequency radio communication, global 
positioning systems (GPS), and power grids.


This
 movie of the March 6, 2012 X5.4 flare was captured by the Solar 
Dynamics Observatory (SDO) in the 171 Angstrom wavelength. One of the 
most dramatic features is the way the entire surface of the sun seems to
 ripple with the force of the eruption.  This movement comes from 
something called EIT waves – because they were first discovered with the
 Extreme ultraviolet Imaging Telescope (EIT) 
 on the Solar Heliospheric Observatory. Since SDO captures images every 
12 seconds, it has been able to map the full evolution of these waves 
and confirm that they can travel across the full breadth of the sun.  
The waves move at over a million miles per hour, zipping from one side 
of the sun to the other in about an hour.  The movie shows two distinct 
waves.  The first seems to spread in all directions; the second is 
narrower, moving toward the southeast.  Such waves are associated with, 
and perhaps trigger, fast coronal mass ejections, so it is likely that 
each one is connected to one of the two CMEs that erupted on March 6. 
Credit: NASA/SDO/AIA

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The sun erupted with one of the largest solar flares of this solar cycle
 on March 6, 2012 at 7PM EST.  This flare was categorized as an X5.4, 
making it the second largest flare -- after an X6.9 on August 9, 2011 --
 since the sun’s activity segued into a period of relatively low 
activity called solar minimum in early 2007. The current increase in the
 number of X-class flares is part of the sun’s normal 11-year solar 
cycle, during which activity on the sun ramps up to solar maximum, which
 is expected to peak in late 2013.

About an hour later, at 8:14 PM ET, March 6, the same region let loose 
an X1.3 class flare.  An X1 is 5 times smaller than an X5 flare.

These X-class flares erupted from an active region named AR 1429 that 
rotated into view on March 2.  Prior to this, the region had already 
produced numerous M-class and one X-class flare.  The region continues 
to rotate across the front of the sun, so the March 6 flare was more 
Earthward facing than the previous ones.  It triggered a temporary radio
 blackout on the sunlit side of Earth that interfered with radio 
navigation and short wave radio.

In association with these flares, the sun also expelled two significant 
coronal mass ejections (CMEs), which are travelling faster than 600 
miles a second and may arrive at Earth in the next few days.  In the 
meantime, the CME associated with the X-class flare from March 4 has 
dumped solar particles and magnetic fields into Earth’s atmosphere and 
distorted Earth's magnetic fields, causing a moderate geomagnetic storm,
 rated a G2 on a scale from G1 to G5.  Such storms happen when the 
magnetic fields around Earth rapidly change strength and shape.  A 
moderate storm usually causes aurora and may interfere with high 
frequency radio transmission near the poles.  This storm is already 
dwindling, but the Earth may experience another enhancement if the most 
recent CMEs are directed toward and impact Earth.