For thousands of years people have been watching the sun. With the invention of the telescope, scientists have been recording the number of spots they see forming on the sun's surface. Sunspots are believed to be the source of solar storms.
According to Matt Penn, an associate astronomer at the National Solar Observatory located here in Tucson, "On the Sun we have sunspots with huge magnetic fields and they're the source of two things that effect us on Earth…Solar flares and also Coronal Mass Ejections. So a Solar flare happens when the magnetic field within these sunspots changes and erupts with light and particles, a CME, a coronal mass ejection happens when an enormous amount of mass is thrown off from again a change in a magnetic field of a sunspot."
Not all solar storms effect the Earth. Many times this matter is hurled into space and never encounters the Earth. The Earth is exposed to solar flares and CMEs from time to time, causing some dramatic effects.
Penn says, "The effects on Earth are really dramatic, and in particular, the more we depend on space assets, satellites for communication or navigation or even high altitude flights, the more of an impact it will have on us on the Earth. For instance, the particles from a solar flare can disrupt the electronics in a satellite and cause dropouts in communication so if you are using your GPS device and the GPS satellite goes out, than you're lost and stuck without navigation."
Even without telescopes, people have known about these storms for some time. The interaction of these storms on the Earth's Atmosphere causes the Aurora that is usually visible near the Poles (between 90-60 degrees).
"We've known about solar storms for a long time by watching the aurora, and what happens when a magnetic gas clouds comes from the sun and interacts with the Earth's magnetic field is it accelerates particles here in the Earth's environment and those can impact our atmosphere causing aurora from glowing molecules in our atmosphere, so we've known about solar interactions for a long time, and those are some of the most beautiful interactions that we can see."
It is not just satellites and the atmosphere affected by these solar storms.
According to Penn, "As long as you have a disturbance in the Earth's magnetic field you can induce currents, in particular if you have a long conductor like a long transmission line along the ground, you can get an overload of current through that line. And this happened way back in the 1800s, where we had telegraph lines across the country which weren't protected properly, at the end of the telegraph line you would have a sparking device to send your message and because the current was too big in this line, the sparks were out of control and they actually burned down telegraph offices back in the 18-hundreds, but also now, even though we have protection in our long lines which are now power transmission lines, we can still overload circuits because the currents that are caused by the magnetic field changes are so large, So in 1989 in Quebec, Canada, Millions of people were without power in the winter because within 30 seconds the currents overloaded some of the circuitry and caused a massive power outage. During a sunspot cycle maximum those events are more likely to occur and so we may be facing more of those in the future."
We study sunspots because we believe them to be the source of solar storms. Sunspots reach a maximum on the surface of the sun every 11 years or so. This cycle is called the "sunspot cycle". The sunspot cycle is actually part of a larger 22 year cycle called "the solar cycle".
"So right now we are going into solar cycle number 24 and we're predicting that around 2012 or at the beginning of 2013 we'll reach the maximum, during a sunspot cycle, we see very few sunspots at first, than they increase to a maximum and then they decrease over an 11 year cycle, so right now we are in the rising phase, so the number of spots that we see is increasing from month to month as we observe the sun."
At this point there is no way to predict when a sunspot will erupt, but the theory is that it has to do with the magnetic fields.
"So in a sunspot when the magnetic field changes it releases energy in the form of a flare or a coronal mass ejection, we think that the magnetic field becomes more complicated as a sunspot may twist or certain other dynamic events occur at a sunspot, so what we look for at our telescopes out at Kitt Peak is the complexity of the magnetic field. Spots with a very complicated magnetic field structure have more energy and are more likely to erupt, spots that are simple and are maybe round and have a simple magnetic field configuration are less likely to erupt."
Once a solar storm erupts, what can we expect on Earth?
"With a solar storm there are really two waves that can really impact the Earth, The first wave is the light and the high energy particles that travel at nearly the speed of light and so we can't really get any warning about that, by the time we see it, the effect is occurring and they're changing our satellites or they are disrupting our electronics. The second wave of a solar storm though can be a magnetized plasma cloud, a river of magnetic gas that takes between, sometimes one or sometimes up to four days to travel from the Sun to the Earth, and so by observing a flare we can predict when this magnetic cloud would impact the Earth, if it will impact the Earth and then make changes to our systems here on Earth to react to that."
These plasma clouds can move at speeds up to a million miles per minute, but that still gives the groups that own and operate satellites two to three days notice before the cloud arrives. This might give them time to react.
"Well if you know a CME is going to impact your satellite, what you can do is shutdown critical circuits. Circuits that have to do with the stabilization of a satellite for instance or circuits that have to do with pointing of communications antenna on the satellites because you certainly don't want your satellite firing jets in orbit or repointing the antenna that talks to the Earth during an event like that. In terms of longer term protection, companies that launch satellites have shielding on them which is basically just mass, lead to protect them from the particles and so you could send up more and more shielding, in particular if you expect solar storms to happen more and more."
Even though companies know about solar storms, sometimes damage still occurs.
"Oh yes many satellites have been lost, many companies may not want to admit that a solar storm was involved in the loss but the coincidences have been pretty clear, as a matter of fact, in 1997, When I was driving to Kitt Peak one morning a communication satellite was knocked out and as I was in Three Points trying to buy gas at the pay-at-the-pump service station, I couldn't because the link between the pay-at-the-pump and my bank was broken because the satellite was off-line from the solar storm. More and more of these things could happen including disruption of the GPS satellite system, in that case, a lot of people depend on that and it could have a lot of impact on people's lives."
Shielding can be added to satellites to protect them, so why is this not done more?
"Whether or not a company protects its satellites enough is really a money issue, the shielding that is necessary to protect your circuits is extra weight and that's the whole cost of launching a satellite is the weight, so in particular in hard economic times, companies are trying to do things on a narrow profit margin and so they may skimp on some of the shielding in that case we maybe more vulnerable to solar disruption."
Some say the sunspot cycle is constant, but the research being done right here at Kitt Peak might change that line of thinking.
Penn says, "My colleague Bill Livingstone and I have been looking at magnetic field strengths and sunspots and we have now a 13 year data set that covers the last solar cycle completely and now the introduction to this cycle into the rise phase, during that time we've seen something that people haven't seen in any other data set, and that is the average magnetic field strength of sunspots has been decreasing, as a matter of fact it has been decreasing in a very linear, very straight line form…the second thing that no one else has seen is there is a threshold, a minimum value of magnetic field strength that's required to form a dark sunspot…so if you take a decreasing magnetic field and a threshold to that eventually, we think, that the magnetic field and sunspots will be too weak to form dark areas on the sun, and we may go into the next cycle, cycle 25 without seeing any sunspots. This has happened once in the history of the sun that we know about, we've observed in the 1600s, it was called the Maunder Minimum period, but it is a unique chance for us now to look at how the sun might go into a minimum period like that and what the physics involved are."
Could this "sunspot minimum" period have an effect on the Earth and in particular the weather?
"There is some controversy as to what would happen during a sunspot minimum, during a grand minimum as we call it. Where many cycles are reduced in amplitude, there is some evidence that there might be some climatic influence, but science is very tough, you can imagine the climate records from the 1600s are pretty sparse, but there also is no real physical connection people are no able to draw the physics out about why that would occur so its pretty much on the speculative side about whether that would have a climatological effect. We think that it may decrease the overall intensity of solar storms that would impact the Earth, but we can't really be sure, we know that the sun erupts and emits magnetized gas plasma even without sunspots and some of those events also impact the Earth, and so even if we don't have sunspots, we'll still have solar storms and they may still be damaging."
These storms often have effects on electronics, but it turns out they can also effect some sports!
"One of the fun things that a solar storm can do in terms of your recreation is that apparently a lot of people race pigeons, homing pigeon races are popular in some parts of the world and there's apparently some betting that goes on with these races, it turns out that homing pigeons use the earth's magnetic field to navigate, during a solar storm, the Earth's magnetic field has changed and some of these pigeons become lost and people loss a lot of money because of this, so solar storms really do have an impact in some recreational sense with us here on the Earth."
We use Satellites for nearly everything we do these days, from making cell phone calls to using your bank card. Nearly everything we do uses communication satellites. These satellites are vulnerable to strong solar storms.
"In terms of day-to-day life, if communication satellites become disrupted then you can imagine that you may not have as easy access to banking or charging your credit card, so things like that become more important, especially as we become more dependent on satellite communication in our daily lives."
"The companies that provide us with communications and navigations really consider this in their overall picture in how they are going to provide the service, but as a solar storm happens that service becomes more and more stressed. So you may go a few days without having navigation if a big solar storm impacts the Earth."
Historically, have there been any storms that, if they were to happen today, would have been a major problem?
"Going back to the 1700s, when Carrington saw this huge flare on the sun, if an eruption like that had an impact on the Earth now, people estimate that there would be trillions of dollars-worth of damage to the power grids, navigation systems and to communication systems. So its kind of a gamble that we're taking, if we're on the hairy edge of protecting our systems and we get a big solar storm, it could cause a lot of damage, so maybe its better to be safe."
So have there been any regulations for people launch satellites to protect them from solar storms?
"I don't think there are any hardware constraints on satellites to protect them from radiation, something that people may not know is if you are flying on a high altitude flight, particularly if you go over the pole, you can get a large dose of X-Rays, basically equivalent to a chest X-Ray if there's a solar storm that's going on and this is something that flight crews, that manage those flights or working on those flights have to deal with. Some of them could be exposed if they were allowed to fly as much to more radiation than nuclear workers, I never really realized this but that's the kind of level that even flying in a high altitude airplane, as your job, you can be exposed to."
Here in Southern Arizona, scientists have great weather, and a great resource at Kitt Peak to observe the Sun.
"So one of the good things about observing the sun from Kitt Peak at the McMath-Peace Telescope is that the telescope is sensitive to inferred light, and that has allowed us to make really sensitive measurements inside the sunspots, so we can measure the complexity and the twist of these magnetic fields and hopefully be able to predict flares and eruptions better."
Sunspots might look small even through a telescope, but these fast moving spots are much larger than they appear.
"Sunspots, the ones that we are looking at now are about two or three times the size of the earth, so these are huge things. The Sun is a hundred earths across, so any dot that you would see is about the size of the earth."
For more on Sunspots and on the work of NSO here in Tucson please visit: http://nsokp.nso.edu/
7831 N. Business Park Drive
Tucson, AZ 85743