Seems like GMU doesn’t stop, waiting for Dave Clarke and John Mashey to launch the next copygate volley. Here’s some interesting research.
FAIRFAX, Va., June 15, 2011—George Mason University scientists discovered recently that a phenomenon called a giant magnetic rope is the cause of solar storms. Confirming the existence of this formation is a key first step in helping to mitigate the adverse effects that solar storm eruptions can have on satellite communications on Earth.
The discovery was made by associate professor Jie Zhang and his graduate student Xin Cheng using images from the NASA Solar Dynamic Observatory (SDO) spacecraft.
Though the magnetic rope was believed to be the cause of these giant eruptions on the Sun, scientists had previously not been able to prove this phenomenon existed because of how quickly the rope moves.
However, through close examination of images taken by the Atmospheric Imaging Assembly (AIA) telescope on board the SDO, Zhang was able to pinpoint an area of the sun where a magnetic rope was forming. The AIA telescope suite is able to capture images of the Sun every 10 seconds, 24 hours a day. This unprecedented
cadence in time helped the discovery.
“The magnetic rope triggers a solar eruption. Scientists have been debating whether or not this magnetic rope exists before a solar eruption. I believe that the result of this excellent observation helps finally solve this controversial issue,” says Zhang.
A solar storm is a violent eruption from the Sun, sending billions of tons of charged material, also called plasma, into space at a speed of more than one million miles per hour. The cloud of plasma carries with it a strong magnetic field. When the magnetized cloud reaches Earth one to three days later, a huge amount of energy is deposited into the magnetosphere of the Earth.
Normally the Earth’s magnetosphere shields this harmful solar wind and protects the environment. However, a solar storm has the potential to disrupt the shielding effect and produce severe space weather, which can have harmful effects on a wide array of technological systems, including satellite operation, communication and navigation and electric power grids.
Zhang’s research will help in giving early warning about solar storms and help to minimize the damage done by space weather here on Earth.
“Understanding the eruption process of these storms will definitely help us better predict them,” says Zhang. “We cannot prevent solar storms, just like we cannot prevent earthquakes or volcanoes. But the development of prediction capacity can help mitigate adverse effects. For instance, satellite operators can power-down key systems to prevent the possible damage to the systems.”
It is widely believed that magnetic fields in the Sun play an essential role in storing energy and powering solar storms. However, the exact form that magnetic field lines take prior to the eruption are highly controversial. Most field lines are semi-circular loops with their foot-points rooted on the surface of the Sun. They cannot erupt easily, and in fact, they often play the role of preventing the eruption.
Scientists suspected that the magnetic rope, if it indeed existed, was the phenomenon that powered the eruption. A magnetic rope contains many magnetic field lines wrapping around a center axis and possibly twisting around each other. Because of the twisting, a strong electric current can be carried by the magnetic rope. Theoretically, the electric current could produce a sufficient electro-magnetic force to overcome the overlying constraining force from other field lines and power the magnetic rope to move outward.
AIA images now reveal that, before an eruption, there is a long and low-lying channel running through the entire active region, which heats to a temperature as high as 10 million degrees, and slowly rises. When it reaches a critical point, it starts to erupt quickly. It is a feature distinctly different from the surrounding magnetic field lines. This particular hot channel is now believed to be the magnetic rope that scientists have been looking for.
Zhang is an associate professor in the School of Physics, Astronomy and Computational Sciences and works with the Space Weather Lab at George Mason University. His results were reported at the American Astronomical Society Solar Physics Division Meeting, held in Las Cruces, New Mexico on June 12 – 16, 2011.
Image-1: http://spaceweather.gmu.edu/press/Figure_1_SDO_171_Full_Size.png
Video-1: http://spaceweather.gmu.edu/press/Movie_1_SDO_171_Full_Size.avi (44 MB)
Image-2: http://spaceweather.gmu.edu/press/Figure_2_SDO_rope_loop.png
Video-2: http://spaceweather.gmu.edu/press/Movie_2_SDO_rope_loop.avi (80 MB)
Caption: http://spaceweather.gmu.edu/press/caption.txt
(Video and images credit: NASA and George Mason University)
tallbloke says:
June 16, 2011 at 11:27 pm
Seems that electromagnetic effects constantly surprise each new generation of physicists by being much bigger than theory says they should be.
You cannot judge from that case. One of the reasons for the test was to see how big the EMP was. The theory is Maxwell’s equations, and if the effects is much bigger than they should be as calculated from Maxwell, then there is something seriously wrong. And there is nothing wrong with those equations.
Leif Svalgaard says:
June 17, 2011 at 5:55 am
tallbloke says:
June 16, 2011 at 11:27 pm
Seems that electromagnetic effects constantly surprise each new generation of physicists by being much bigger than theory says they should be.
You cannot judge from that case.
Yes I can. The explosion was 400km up, In that rarified part of the Earth’s environment which you say shouldn’t affect us down here at sea level.
How many joules in that explosion Leif? More or less than a 6.5 earthquake?
I can’t believe the argument over whether magnetic field lines exist actually happened. Everyone agreed they are useful abstractions but then proceeded to beat their heads against a semantic wall over whether that means they “exist” or not. On a more general note, interesting to see big bang denial crop up in a global warming denial forum. I’ve always thought the two were incredibly similar when conducted by non-creationists.
tallbloke says:
June 17, 2011 at 11:33 am
“You cannot judge from that case.”
Yes I can. The explosion was 400km up, In that rarified part of the Earth’s environment which you say shouldn’t affect us down here at sea level. How many joules in that explosion Leif? More or less than a 6.5 earthquake?
No, you can’t unless you know what you talking about, which you obviously don’t. The way a nuclear EMP works is that gamma rays from the explosion penetrate to ~30 km altitude and there where the air is dense enough knocks electrons out of the atoms. The electrons spiral along the magnetic field lines. This is the Compton effect; the resulting electrons produce an electric current called the Compton current. The energy of the gamma rays was about 1/1000 of the nuclear blast [which was a modest 1.4 MegaTon TNT equivalent], or 6E12 Joule. The 6.5 earthquake is about 5E14 J.
Physiscs had calculated the effect of the EMP, but were not sure how efficient the process would be at great altitudes. The StarFish explosion was partly to calibrate that calculation. Your silly surmission that each new generation is stumped by this, is just that: untrue and silly.
Ryan says:
June 17, 2011 at 12:31 pm
I can’t believe the argument over whether magnetic field lines exist actually happened. Everyone agreed they are useful abstractions but then proceeded to beat their heads against a semantic wall over whether that means they “exist” or not.
It crops up regularly and the purpose of pushing it is basically to say that modern science [which uses that very sensible and useful device] is fundamentally wrong, because ‘field lines don’t exist’. This is not a science argument, but an attempt of credibility assassination.
Leif Svalgaard says:
June 17, 2011 at 1:09 pm
Physiscs had calculated the effect of the EMP, but were not sure how efficient the process would be at great altitudes. The StarFish explosion was partly to calibrate that calculation. Your silly surmission that each new generation is stumped by this, is just that: untrue and silly.
You’ve misunderstood me. I’m not saying that particular effect is incorrectly estimated by successive generations of physicists, I’m saying that analogous problems in differing environments have been underestimated since, and that this is a consistent pattern. So for example, not very long ago, in the experiment where a probe threw a projectile at a passing comet with the intention of measuring the size of the resulting pock mark, the scientists expressed surprise at the much bigger flash and resulting crater that occurred than was expected.
Leif writes : “This is true in a non-conductor like air or a vacuum, but in a plasma things are more complicated. There, the particles are bound to magnetic field lines and spiral around them. The plasma and the field are tied together and move together. In that sense the field lines have individuality and can be said to exist. It is a useful to accept this and that is really what counts. Most scientists don’t give a hoot about what ‘exists’ in ‘reality’ [and what does that actually mean?]. They care about what works and since plasma and field lines go together, if plasma exists it is useful to treat field lines as existing too.”
It is useful to use analogies to understand physical behaviour but potentially wrong when the analogous properties are explored further. So in this case any expectation of “lines” that goes beyond the observed fact that the particles line up along them is very possibly going to be misleading. Considering things like “line density” could be a non effect that might lead to further misunderstandings for example.
tallbloke says:
June 17, 2011 at 2:37 pm
I’m saying that analogous problems in differing environments have been underestimated since, and that this is a consistent pattern.
Not at all, only if you have that attitude and look for confirmation bias. Some counterexamples: recent solar cycle predictions, global warming, Obama’s approval rating, etc, etc
TimTheToolMan says:
June 17, 2011 at 5:41 pm
It is useful to use analogies to understand physical behaviour but potentially wrong when the analogous properties are explored further.
Physicists know when to use it and when not go any further, so no understandings among us. The problem comes when laymen try to use the ‘non-existence’ of field lines as an indication that physicists don’t know what they are talking about.
Asking questions to improve one’s knowledge about a subject is one thing; questioning every little concept that is used to describe/explain a physical scenario is taking an excessive denialist attitude (pun intended).
Solar physicists’ knowledge of the Sun is based on some decades of observations (centuries, if we include sunspot counts) and analysis, based by solid physics (electromagnetism, plasma physics, quantum physics, etc), and not on closed-code computer model predictions (again, pun intended)… There are, of course, still more question than answers, but no one is sitting on ether here.
So, my point, a little bit of Google+Wikipedia would have avoided some friction in this thread. No one likes a comment section in flames, right?
Leif Svalgaard says:
June 17, 2011 at 9:31 pm
…
Leif, a simple dipole magnet has the ‘field lines’ going from one pole to the other, but the Sun has a lot of plasma shooting out sideways from the equatorial region, and a ‘current sheet’ which is of opposite sign above and below. It’s almost as if the sun contains two dipole magnets one above the other, which don’t ‘join’ in the middle.
I’m supposing the ‘field lines’ associated with the sideways radiating plasma above and below the current sheet eventually recirculate to their respective poles, as they can’t just ‘peter out’ or flap around in free space.
What is the solar physicists conceptual model which explains this apparent paradox?
tallbloke says:
June 18, 2011 at 1:10 am
a simple dipole magnet has the ‘field lines’ going from one pole to the other, but the Sun has a lot of plasma shooting out sideways from the equatorial region, and a ‘current sheet’ which is of opposite sign above and below. It’s almost as if the sun contains two dipole magnets one above the other, which don’t ‘join’ in the middle. What is the solar physicists conceptual model which explains this apparent paradox?
The plasma ‘shoots’ out everywhere [called the solar wind], not just at the equator. And the Sun is [to first approximation] a dipole, too. In the Northern Hemisphere the field lines go out [say, but changes every 11 years at solar maximum] while in the Southern Hemisphere the field lines go in [opposite of Northern]. So, a nice dipole. If there were no solar wind, the field lines from that dipole would cross the equator from North to South and be perpendicular to the equatorial plane. But the solar wind plasma drags that field line out radially away from the Sun, so that the field line will have two ‘legs’ that are still connected to the Sun, but stretching out to infinity [this resolves the paradox: the field line turns around at infinity]. In the Northern leg the field points out, and in the Southern leg it points in. Because charged particles gyrate around field lines [ http://www.leif.org/research/Current-Sheet-Cartoon.png ] a current develops between the oppositely directed field lines. Now, this is the picture to first approximation [that has no paradox]. But the situation is not so as simple as that. The solar field is not a pure dipole, but has many higher order multipoles. These deform and warp the magnetic field in the Heliosphere. Those warps can be very large and can extend all the way to the poles, especially at solar maximum where the polar fields disappear [but still no paradox]. See http://www.leif.org/research/3D-solar-Wind.pdf that describes the current paradigm, now some 35 years old, but still valid]. Second point: the solar wind does not extend to infinity, but meets the interstellar medium some 100 AU from the Sun. There the wind gets all tangled up, but eventually the field lines connect with the interstellar magnetic field, which connects with the intergalactic magnetic field, so we can continue to follow the field line on its way to infinity and there is still no paradox.