A Solar Science Primer

Due to the recent appearance of a very large active solar region (also known as a sunspot group) there has been a resurgence of interest in solar activity on ATS. This may be a good time for a refresher in the terminology and a bit of the science of what our star does.

A sunspot is a visible dark area on the photosphere (more or less the “surface” of the sun). They are dark because they are somewhat cooler than the surrounding area but cooler does not mean cool, just not as hot. They are also “clumps” of magnetic activity. It is thought that this activity is the result of convective activity deeper in the Sun where swirling plasma creates electrical currents which in turn produce magnetic fields. Sunspots usually occur in groups which, in solar science, are referred to as active regions. While the size of an active region is of interest it is the magnetic configuration which is of most importance. This can range from very simple (where all the spots “line up” magnetically) to highly complex which each spot of the group carrying its own separate field and conflicting with its neighbors. The more complex the magnetic configuration, the more likely that the fields will produce a sort of magnetic “short circuit” resulting in a solar flare. It is the configuration which space weather scientists are most interested in, not so much the size of the region.
www.swpc.noaa.gov...
www.spaceweatherlive.com...



A solar flare is a burst of electromagnetic radiation (x-rays, uv, visible light, infrared, radio). The intensity of flares is measured in the x-ray and are given letter classifications. In lowest to highest; A, B, C, M, X. Within each class is a numeric logarithmic subvalue between 1 and 9 (except for X class flares which are open ended). So, an M2 flare is twice as intense as an M1 flare and an X1 flare is 10 times stronger than an M1. The strongest flare observed occurred in 2003, it went off the scale of all recording devices but is estimated to have been an X28. (Yes, that is a wow!)

Being electromagnetic radiation and traveling at the speed of light, the effects of a solar flare on Earth are experienced at virtually the same time the flare is detected. These effects depend upon the strength of the flare but only really affect the very upper regions of the atmosphere. The denser lower atmosphere quickly absorbs the high energy components (x-rays, and UV) so that by the time the energy reaches the surface the only signs would be a burst of radio noise and a flash of light (if you happened to be observing the sunspot at the time). That’s why satellites are used to observe and measure the intensity of flares. But in the upper atmosphere the situation is different. There, the unadulterated energy tears electrons from atoms, ionizing them. In some cases, this causes problems; it makes it harder for satellites (including GPS satellites) to communicate with surface stations. But it also makes it easier for radio signals from the surface to bounce off the ionosphere back to the surface. Ham radio operators love it because it makes long distance contacts easy. These effects are short lived, lasting a few hours after the flare as the level of ionization returns to normal.

Next. CMEs

Thanks Phage. I have always had a problem really understanding the sun and it activities. Where were you when I was in college? Great job putting it in laymans terms.

Coronal mass ejections are another aspect of solar science which can have effects on Earth. Like solar flares, they are related to active solar regions. When the convoluted magnetic fields of a sunspot rip loose from the Sun they drag plasma (hot ionized material) with them into space. A CME is, literally, an ejection of coronal material. While the same phenomena which produce solar flares can also produce CMEs, this is not always the case. The recent activity seen with active region 2192 drove this point home, producing several X class flares with no associated CMEs.

There is no classification system for CMEs (other than, "gosh, that was a big 'un"). Also, unlike solar flares, CMEs do not travel at the speed of light but they can travel very fast, potentially traveling the 93 million miles from the Sun to Earth in less than a day. Also unlike solar flares, CMEs have the potential to cause more than effects on radio communications.

First, in order to have any effect on Earth, a CME must encounter Earth. It must leave the sun when the region it erupts from is pointed in just the right direction. Think of it as if there is a water gun with a fixed mount on a merry go round. Think of the Earth as someone who is walking slowly around the merry go round a good distance away. Chances are, a random shot from the water gun is not going to hit the person. Add a vertical component and the chances that Earth will be hit by any particular CME are not that great. Of course, if that water gun is capable of rapid fire, the chances that the person will get wet at some point goes up. While a CME can occur at any time the Sun is more active during solar maximum so it is more likely that the Earth will happen to be in the same place at the same time as a CME at this time.

What effects a CME will have if it does encounter Earth depends upon a few main factors. The density of the CME is very important. While a CME is actually a very ephemeral thing (a better vacuum than can be produced in labs), their density can vary quite a bit. The speed at which it travels is also important. The faster it is, the more punch it can carry. But the most important factor seems to be the magnetic configuration of the CME.

When the CME left the Sun it carried some of those complex magnetic fields from the active region with it. Those magnetic fields determine how the CME will interact with the Earth's magnetic field. That interaction is what determines what the effects of the CME will be on Earth. If the field of the CME matches that of Earth, there is an effect similar to that of trying to push two north poles of a couple of magnets together. The fields fight each other. If the field of the CME goes the other way (a "south turn") the fields will hold hands with each other. This is where the particles carried by the CME come into the picture. If the fields are matched, the particles will be deflected by Earth's magnetic field and tend to stream off into space as the CME blows by. On the other hand, if the fields are opposed, if they are holding hands, the particles are given a free ride into the magnetic field.

The solar particles start collecting in the magnetic field, "charging" it and moving around in it, they start producing electrical currents. Those electrical currents start producing moving magnetic fields of their own. And those magnetic fields can reach down to Earth's surface. It's those wiggling magnetic fields produced by those solar particles which is known as a geomagnetic storm. It is also those solar particles, being pulled to the north and south poles by the Earth's magnetic field which are pulled downward at the poles (because the field is vertical at the poles) and into the upper atmosphere where they slam into the atoms there. They release the energy they carried from the Sun and produce the light show known as the aurora.

Solar coronal holes are what first brought me to ATS, I was seeking information on them. Everything we need to know in one easy to understand package. Thanks Phage.

a reply to: Iamschist

Except that I didn't address coronal holes. Yet another aspect but one that will have to wait a bit.

a reply to: Phage

Well get on the stick man! ;-p

I always like to include some supporting history in these threads since we have K-12 readers that could miss the esoteric links.
Richard Carrington was one of the first to analyze solar flares and you may find some interesting sidebar there.
en.wikipedia.org...

The 1956 CME was also interesting.
The most recent Solar high energy studies are probably quarantined but that doesn't mean no information can be found.

Phage quick question Since your the sun "GURU" can you list the effects or affects on health??? a reply to: Phage

a reply to: ATF1886
Not a guru. I just find the scientific aspect interesting and happened to be asked to start this thread.

No health issues to be expected, however some people claim to be sensitive to both flares and geomagnetic storms in various ways.

No sarcasm towards you i actually find you as a guru your bright in this category i respect your knowledge to the utmost the reason i ask and now im no e dames but when a flare hits i feel heavy vibrations when i walk i get a bit short of breath palpatations and dependng when its either X-M-OR PROTON is when i feel it is it just me?? And the rason for asking is that when they hit of you look at the image below s a bit of but say were the concentration of flare is at does that mean thats where flare hit?? a reply to: Phage

Solar Symptoms and Side Effects

Psychological effects of CMEs (coronal mass ejections) are typically short lived and include headache, palpitations, mood swings, and feeling generally unwell. Chaotic or confused thinking, and erratic behaviors also increase. Since Tuesday’s solar flare was a double-whammy, it will be interesting to see whether reports of physical disturbances are more intense or more plentiful than during single solar plasma blasts.

Solar eruptions throw 10 billion kilograms, or 22 billion pounds, of solar plasma into space. If that number is hard to grasp, just think of it as ginormous. One to three flares are a daily occurrence on the sun but the waves of charged particles do not always visit our planet. Those that do reach us are both beauty and a possible beast.

link

Mod Edit: External Source Tags – Please Review This Link.

a reply to: ATF1886

And the rason for asking is that when they hit of you look at the image below s a bit of but say were the concentration of flare is at does that mean thats where flare hit?

Mostly it shows where it was noon, where the Sun was overhead. Flares only affect the day side of Earth. But yes, as I said, solar flares affect communications. That chart is a prediction of how radio waves are absorbed by the D region of the ionosphere.

Conditions in the D region of the ionosphere have a dramatic effect on high frequency (HF) communications and low frequency (LF) navigation systems. The global D Region Absorption Predictions (D-RAP) depicts the D region at high latitudes where it is driven by particles as well as low latitudes, where photons cause the prompt changes. This product merges all latitudes using appropriate displays, and is useful to customers from a broad base that includes emergency management, aviation and maritime users.

www.swpc.noaa.gov...

a reply to: Phage

Do you think there is a correlation between massive cme's like the x28 in 2003 and global warming like the killer heat wave earlier that same year? Could they both have had a common agitator?

a reply to: luxordelphi

Do you think there is a correlation between massive cme's like the x28 in 2003 and global warming like the killer heat wave earlier that same year? Could they both have had a common agitator?

1) There is no such thing as an X28 CME. There is no classification system for CMEs.
2) A correlation can mean that two or more things happen at more or less the same time. I guess you could say there was a correlation. I wouldn't.
3) No, I don't think that a summer heat wave in Europe had a causal relationship to the flare in October.

Good job Phage Thanks, I am learning already.

I'll S+F this. It's great info. I wish it would get more reception so future solar panic threads have more insight and less frequency

originally posted by: Phage
a reply to: ATF1886
Not a guru. I just find the scientific aspect interesting and happened to be asked to start this thread.

Thanks for the good thread phage.

I always expected that health issues related to solar activity would be insignificant at latitudes that most people live at. However, I also wondered if there were say some scientific expeditions into the polar regions, if people in those typically non-residential areas might experience possible health effects from the increased activity of charged particles which obviously increases auroral activity.

The other possibility for health effects on astronauts leaving earth's orbit hasn't been an issue since what, 1972 I guess?

Astronauts on their way to the moon were at some small risk, though the odds were in their favor of not having a CME encounter in such a short mission time. A manned mission to Mars would be a different story if the trip took say 6 months (or more) which would increase the risk to astronauts of a CME encounter, compared to the 3 day trip to the moon.

Thanks Phage i too also find this interesting.

a reply to: Abort75

Funny avatar looks like someone i thought i knew, thought i knew someone else feel me?

Anyway on topic, the science behind this phenomenon is really cool, wants you break down the actual quantum dynamics behind it...