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How Solar Flares Will Leave The Earth And Its Inhabitants Mostly Unharmed

by Dani Johnson

May 17, 2013

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Donate Since we are in the peak (solar maximum) of the Sun's 11 year cycle, we are seeing much more solar activity than we have in the past few years. It may seem scary to some, but the sun has been operating in this way for way longer than we have been able to observe it and longer than we can even conceive. Increased solar activity means more sunspots, solar flares, coronal mass ejections and coronal holes. From our vantage point, it also means more gorgeous auroras! The news feeds have been steadily buzzing about the four x-class solar flares that erupted from the Sun starting on Monday, May 13th. These flares are typical to the solar maximum, but they have still managed to set off many people in fear and trembling. Fortunately, since the Earth evolved in a highly radioactive environment, it has a protective magnetosphere, ionosphere and atmosphere to keep it (and its inhabitants) safe from solar weather. This doesn't mean that solar activity will not affect us down here under the protective layers, though; our satellites and the International Space Station (ISS) are in orbit high enough that they are susceptible to damage from charged particles or waves from the electromagnetic spectrum (such as x-rays and gamma rays).

Solar activity can also cause a geomagnetic storm to occur in our magnetosphere that will produce the beautiful Aurora Borealis. While geomagnetic storms are usually harmless to us, it is possible for them to damage communication satellites (including GPS satellites) and cause massive power surges that may black out entire grids for long periods of time. Such events have happened in the past, but with our current technology we are able to better predict when a solar flare or coronal mass ejection will occur or at the very least we are able to see when one is actually happening which gives us time to prepare. Companies that have a product that is particularly susceptible to damage take advantage of this technology to know when to protect their devices and satellites are even equipped with proper shielding to keep its delicate parts safe from solar radiation. More importantly, astronauts aboard the ISS use this technology to know when they should remain inside the space station's protective walls.

Solar flares originate inside of a sunspot, which is a cooler spot on the surface of the sun that contains strong magnetic fields that are constantly shifting. These sunspots often occur in clusters and these clusters commonly produce solar flares and CMEs. A solar flare is when the energy from the constantly shifting magnetic fields is explosively propelled into space. Flares emit wavelengths from the entire electromagnetic spectrum, including x-rays and gamma rays which are the most dangerous. These waves are easily deflected with sheets of aluminum or other metals, which is how satellites and astronauts are protected.

A coronal mass ejection, or CME, commonly occurs with a solar flare, but it is definitely not uncommon for either of them to erupt independently. A CME originates in the corona, or the outer atmosphere on the Sun, where the sudden and violent release of energy sends charged particles in a steady stream toward whatever happens to lie in its path. If the CME is directed towards Earth, CMEs can cause a geomagnetic storm, which is basically the charged particles interacting with the Earth's magnetosphere. These storms not only produce magnificent auroras, but they can also be dangerous to astronauts in space, devices such as satellites as well as power lines. However, as mentioned before, the companies responsible for susceptible products are well versed in space weather and know when to take proper measures to keep their devices or astronauts safe.

That's all really informative, but the real question humming in the back of our minds is what if the Sun produced an incredibly strong solar flare or CME and Earth was staring down the barrel of the explosion, could we survive? While we cannot deny that serious Earth damaging flares or CMEs are certainly a possibility, we can be pretty sure that it is highly unlikely to happen. We have witnessed other, bigger stars emitting flares that would be deadly to an Earth-like planet orbiting at roughly the same distance, but our Sun just isn't as powerful as those bigger stars. The Sun has been shining light towards the Earth for at least 4 billion years and humans have been keeping close tabs on it for the last few hundred years and there hasn't been any evidence to suggest that any mass extinction scenario involving the Sun has occurred in the past. The strongest flare known was the Carrington event in 1859, and even that flare couldn't penetrate our atmosphere and magnetosphere.

Now, let's take a look at these jaw-dropping flares!

I acquired these images from the Solar Dynamics Observatory Mission Blog.

The image above is from the AIA 1600 channel for 0248 UTC 13-May-2013. It shows a nice set of loops rising over the flaring region, which is just over the limb. This channel measures C IV emissions. These loops are about 26 km (16 million miles) high, a little over twice the diameter of the Earth. They are visible about 21 minutes after the peak in the X-ray irradiance.

This X3.2 flare peaked at 0111 UTC on 14-May-2013 (9:11 pm ET on 13-May-2013). Here are some stills from AIA 1600 and 1700 and the HMI continuum.

The above image is from later in the flare (0200 UTC) and shows the loops in 1600, with a bridge moving toward the upper right of the frame.

The above image is a little earlier (0148 UTC) but is the best time to see the wisps of coronal loops in this channel. There is a little wisp of light above the loops that is also seen in the 1600 passband on left.

The HMI continuum image above (also at 0200 UTC) shows the sunspot that is producing these flares.

AR 11748 unleashed another X-class flare last night. It was an X1.2, peaking at 0148 UTC, 15-May-2013 (9:48 pm ET, 14-May-2013). The location was N11, E63, a little south of the earlier flares but in the same active region. Here is the post-flare arcade, nicely displayed in AIA 335 the light of Fe XVI, which measures plasma at 2.5 million Kelvin. This is almost 10 hours after the peak and the loops are still bright.

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by Dani Johnson

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