What are solar flares?

Question

First off, I'm not one of those 2012 freaks, I don't blindly believe in every bit of nonsense someone tries to sell me.

I have been reading about the theories a lot and there is a particular one that caught my eye.

It is said that solar minimum has arrived and that the Sun could burst any minute now.

I tried to look in to the idea, but I couldn't find a single article about what solar flares actually ARE.

Why they are (if they even are) dangerous, why do so many people fear them, what do they do and so on.

I checked the NASA web site and still had no luck.

I'm asking for a detailed explanation of solar flares, what they are, how they become, what effect they have on Earth and so on.

I'm especially interested in why they're supposed to be dangerous to mankind.

A link to a pre-written explanation or maybe even an article will be sufficient.

Thanks in advance, I hope you can help.

Answer 1

A solar flare is a huge streak of plasma (superheated gas) that shoots out from the sun and forms an arc as powerful magnetic fields pull it back in.  Sometimes solar flares are strong enough to leave the sun and head out in to space.  Sometimes these flares reach earth and cause black outs but most of the time are trapped within earth's own magnetic field and are pulled towards the poles.  I hope this helps.  

Answer 2

Solar flares are not dangerous to mankind. We are protected from the atomic ejecta by our atmosphere and our magnetic felds. Solar Flars do produce high speed atomic particles which speed thorugh space and would be dangerous to astronauts who woul dnot be shielded from this "radiation".

Solar flares cycle on about an 11 year basis. The Sun has many rythmn's in it's operation. During Solar Max, many sunspots are seen and many flares occur. The ejecta produced by a large flare consists of atomic nuclei, mostly protons and neutrons. These particles are travelling quite fast (close to lightspeed) and slam into the earths upper atmoshphere. The particles spiral in along the earths magnetic fields. The interaction between the particles and the upper atmosphere produces the Northern Lights and can lead to an increased ionization of the upper atmosphere which can disrupt radio communications.

No one knows exaclty what produces a sun spot or a flare, but if you think of the sun as a ball of fluid of sorts, a flare is a bit like a bubble in a pot of boiling water.

A helpful reference would be:

http://hesperia.gsfc.nasa.gov/sftheory/s...

Answer 3

Solar flares are bursts of charged particles from the Sun. The concern is that a strong enough flare, or series of flares, could be strong enough to penetrate our planet's atmospheric defenses, and essentially irradiate life forms on the ground. Like us.

However, that is just my understanding. If you look at the wikipedia link, there doesn't seem to be any concern over these particles reaching the surface of Planet Earth. The only concerns mentioned are for satellites, astronauts, and explorers sent to Mars (and by extension, anywhere in space where there isn't an Earth-like atmosphere to protect you).

There doesn't seem to be much to worry about... ?

Answer 4

Solar minimum is a time when there are very few sun spots.  

Solar flares are caused by the magnetic field of the Sun.  The Sun's magnetic field tends to form loops vertically and magnetically charged particles form streams along these loops.  But the substance of the Sun doesn't rotate as a solid.  The stuff at the equator goes more slowly in radial terms, because it has farther to go (just as it takes Pluto over 300 years to go around the Sun and Mercury only 72 days).  This causes the loops of the field to stretch out and eventually break.  The breaks whip through the substance of the Sun, and where they break the surface, solar flares burst out.  

In general, we are protected from the solar flares, however, the magnetic field of the Earth appears to be in the process of flipping.  When this happens, there will be a brief period (perhaps a few decades) when the Earth will have a much lower strength magnetic field, and what field exists will be localized and confused.  We will not have nearly as much protection as we have had in the past.  There's an excellent Nova episode called Magnetic Storm that might interest you.  My library had a copy.

http://www.pbs.org/wgbh/nova/magnetic/

Answer 5

A flare is defined as a sudden, rapid, and intense variation in brightness. A solar flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released. Radiation is emitted across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to x-rays and gamma rays at the short wavelength end. The amount of energy released is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time! The first solar flare recorded in astronomical literature was on September 1, 1859. Two scientists, Richard C. Carrington and Richard Hodgson, were independently observing sunspots at the time, when they viewed a large flare in white light.

As the magnetic energy is being released, particles, including electrons, protons, and heavy nuclei, are heated and accelerated in the solar atmosphere. The energy released during a flare is typically on the order of 1027 ergs per second. Large flares can emit up to 1032 ergs of energy. This energy is ten million times greater than the energy released from a volcanic explosion. On the other hand, it is less than one-tenth of the total energy emitted by the Sun every second.

There are typically three stages to a solar flare. First is the precursor stage, where the release of magnetic energy is triggered. Soft x-ray emission is detected in this stage. In the second or impulsive stage, protons and electrons are accelerated to energies exceeding 1 MeV. During the impulsive stage, radio waves, hard x-rays, and gamma rays are emitted. The gradual build up and decay of soft x-rays can be detected in the third, decay stage. The duration of these stages can be as short as a few seconds or as long as an hour.

Solar flares extend out to the layer of the Sun called the corona. The corona is the outermost atmosphere of the Sun, consisting of highly rarefied gas. This gas normally has a temperature of a few million degrees Kelvin. Inside a flare, the temperature typically reaches 10 or 20 million degrees Kelvin, and can be as high as 100 million degrees Kelvin. The corona is visible in soft x-rays, as in the above image. Notice that the corona is not uniformly bright, but is concentrated around the solar equator in loop-shaped features. These bright loops are located within and connect areas of strong magnetic field called active regions. Sunspots are located within these active regions. Solar flares occur in active regions.

The frequency of flares coincides with the Sun's eleven year cycle. When the solar cycle is at a minimum, active regions are small and rare and few solar flares are detected. These increase in number as the Sun approaches the maximum part of its cycle. The Sun will reach its next maximum in the year 2011, give or take one year.

A person cannot view a solar flare by simply staring at the Sun. (NEVER LOOK DIRECTLY AT THE SUN! EYE DAMAGE CAN RESULT.) Flares are in fact difficult to see against the bright emission from the photosphere. Instead, specialized scientific instruments are used to detect the radiation signatures emitted during a flare. The radio and optical emissions from flares can be observed with telescopes on the Earth. Energetic emissions such as x-rays and gamma rays require telescopes located in space, since these emissions do not penetrate the Earth's atmosphere.

5 November, 2003 - BBC News

The Sun has unleashed its largest recorded solar flare, capping 10 days of unprecedented activity for the star.

The blast sent billions of tonnes of superhot gas into space - some of it directed towards our planet.

Our planet's magnetic sheath can be hit by clouds of charged particles, which could give rise to geomagnetic storms.

Scientists say the Sun's current spate of activity has produced the most dramatic events seen on the solar surface since regular monitoring began.

The Aurorae (dancing polar lights) are generated when fast-moving particles (electrons and protons) ejected from the Sun get trapped in the magnetic field around the Earth, and collide with the gases in the upper atmosphere.

Some orbiting satellites could be in the firing line, too. The mass of electrons contained in these surges can damage onboard microchips. Operations may need to be temporarily suspended to protect sensitive equipment.

And high energy radiation hitting our atmosphere could also interrupt short-wave radio transmissions and cause errors in navigation systems.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one each week when the Sun is "quiet". Large flares are less frequent than smaller ones. Solar activity varies with an 11-year cycle (the solar cycle). At the peak of the cycle there are typically more sunspots on the Sun, and hence more solar flares.

Most proton storms take two or more hours from the time of visual detection to reach Earth. A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured, taking only 15 minutes after observation to reach Earth, indicating a velocity of approximately one-third light speed.

The radiation risk posed by solar flares and CMEs is one of the major concerns in discussions of manned missions to Mars or to the moon. Some kind of physical or magnetic shielding would be required to protect the astronauts. Originally it was thought that astronauts would have two hours time to get into shelter, but based on the January 20, 2005 event, they may have as little as 15 minutes to do so.

On Earth, our magnetic field protects us from the radiation.