What Is a Solar Storm?
what do you think of when you hear the word “storm”? Images of rolling black clouds might fill your mind. The crack of thunder probably fills your ears. Your eyes may search the sky for bolts of lightning.
But what about a solar storm? Would you believe the Earth is occasionally hit with solar storms and you probably don’t see or hear any of the things just mentioned?
A solar storm is a term used for atmospheric effects felt on Earth from certain events that occur on the Sun. You probably think of the Sun as a bright shining light that never changes. In reality, it’s an unbelievably huge ball of molten gases that’s constantly in flux.
Solar storms occur when the Sun emits huge bursts of energy in the form of solar flares and coronal mass ejections. These phenomena send a stream of electrical charges and magnetic fields toward the Earth at a speed of about three million miles per hour.
When a solar storm strikes the Earth, it often produces a dazzling “northern lights” display in parts of the atmosphere that can be seen in areas close to the Arctic Circle. Solar storms can also disrupt satellites and various forms of electronic communications.
Solar storms start with a huge explosion on the Sun. These explosions — called solar flares — can be about as powerful as billions of nuclear bombs!
Solar flares usually go hand-in-hand with the release of huge streams of charged plasma that travel at millions of miles per hour. These streams are called coronal mass ejections, or CMEs. When CMEs hit the Earth, they can cause geomagnetic storms that disrupt satellites and electrical power grids.
For example, in February 2011, a CME produced by an especially-powerful solar flare disrupted radio communications throughout China. Some experts believe a major solar storm could cause over 20 times the economic damage of the worst hurricane.
Scientists who study solar storms have discovered that the frequency of solar flares appears to follow an 11-year solar cycle. At times of peak activity, there could be several solar storms each day. At other times, there might be less than one solar storm per week. Scientists expect the Sun’s current activity cycle to result in a peak in solar storms during 2024.
Solar Storm and Space Weather
What is solar activity?
Solar flares, coronal mass ejections, high-speed solar wind, and solar energetic particles are all forms of solar activity. All solar activity is driven by the solar magnetic field.
What is a solar flare?
A solar flare is an intense burst of radiation coming from the release of magnetic energy associated with sunspots. Flares are our solar system’s largest explosive events. They are seen as bright areas on the sun and they can last from minutes to hours. We typically see a solar flare by the photons (or light) it releases, at most every wavelength of the spectrum. The primary ways we monitor flares are in x-rays and optical light. Flares are also sites where particles (electrons, protons, and heavier particles) are accelerated.
What is a solar prominence?
A solar prominence (also known as a filament when viewed against the solar disk) is a large, bright feature extending outward from the Sun’s surface. Prominences are anchored to the Sun’s surface in the photosphere, and extend outwards into the Sun’s hot outer atmosphere, called the corona. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months, looping hundreds of thousands of miles into space. Scientists are still researching how and why prominences are formed.
The red-glowing looped material is plasma, a hot gas comprised of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo. An erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma.
What is a coronal mass ejection or CME?
The outer solar atmosphere, the corona, is structured by strong magnetic fields. Where these fields are closed, often above sunspot groups, the confined solar atmosphere can suddenly and violently release bubbles of gas and magnetic fields called coronal mass ejections. A large CME can contain a billion tons of matter that can be accelerated to several million miles per hour in a spectacular explosion. Solar material streams out through the interplanetary medium, impacting any planet or spacecraft in its path. CMEs are sometimes associated with flares but can occur independently.
Does ALL solar activity impact Earth? Why or why not?
Solar activity associated with Space Weather can be divided into four main components: solar flares, coronal mass ejections, high-speed solar wind, and solar energetic particles.
Solar flares impact Earth only when they occur on the side of the sun facing Earth. Because flares are made of photons, they travel out directly from the flare site, so if we can see the flare, we can be impacted by it.
Coronal mass ejections, also called CMEs, are large clouds of plasma and magnetic field that erupt from the sun. These clouds can erupt in any direction, and then continue on in that direction, plowing right through the solar wind. Only when the cloud is aimed at Earth will the CME hit Earth and therefore cause impacts.
High-speed solar wind streams come from areas on the sun known as coronal holes. These holes can form anywhere on the sun and usually, only when they are closer to the solar equator, do the winds they produce impact Earth.
Solar energetic particles are high-energy charged particles, primarily thought to be released by shocks formed at the front of coronal mass ejections and solar flares. When a CME cloud plows through the solar wind, high velocity solar energetic particles can be produced and because they are charged, they must follow the magnetic field lines that pervade the space between the Sun and the Earth. Therefore, only the charged particles that follow magnetic field lines that intersect the Earth will result in impacts.
What are coronal holes?
Coronal holes are variable solar features that can last for weeks to months. They are large, dark areas (representing regions of lower coronal density) when the sun is viewed in EUV or x-ray wavelengths, sometimes as large as a quarter of the sun’s surface. These holes are rooted in large cells of unipolar magnetic fields on the sun’s surface; their field lines extend far out into the solar system. These open field lines allow a continuous outflow of high-speed solar wind. Coronal holes tend to be most numerous in the years following solar maximum.
What is a geomagnetic storm?
The Earth’s magnetosphere is created by our magnetic field and protects us from most of the particles the sun emits. When a CME or high-speed stream arrives at Earth it buffets the magnetosphere. If the arriving solar magnetic field is directed southward it interacts strongly with the oppositely oriented magnetic field of the Earth. The Earth’s magnetic field is then peeled open like an onion allowing energetic solar wind particles to stream down the field lines to hit the atmosphere over the poles. At the Earth’s surface a magnetic storm is seen as a rapid drop in the Earth’s magnetic field strength. This decrease lasts about 6 to 12 hours, after which the magnetic field gradually recovers over a period of several days.
What is a sunspot?
Sunspots, dark areas on the solar surface, contain strong magnetic fields that are constantly shifting. A moderate-sized sunspot is about as large as the Earth. Sunspots form and dissipate over periods of days or weeks. They occur when strong magnetic fields emerge through the solar surface and allow the area to cool slightly, from a background value of 6000 ° C down to about 4200 ° C; this area appears as a dark spot in contrast with the very bright photosphere of the sun. The rotation of these sunspots can be seen on the solar surface; they take about 27 days to make a complete rotation as seen from Earth.
Sunspots remain more or less in place on the sun. Near the solar equator the surface rotates at a faster rate than near the solar poles. Groups of sunspots, especially those with complex magnetic field configurations, are often the sites of solar flares. Over the last 300 years, the average number of sunspots has regularly waxed and waned in an 11-year (on average) solar or sunspot cycle.
What is the solar cycle?
The sun goes through periodic variations or cycles of high and low activity that repeat approximately every 11 years. Although cycles as short as 9 years and as long as 14 years have been observed. The solar or sunspot cycle is a useful way to mark the changes in the sun.
What is solar maximum and solar minimum?
Solar minimum refers to a period of several Earth years when the number of sunspots is lowest; solar maximum occurs in the years when sunspots are most numerous. During solar maximum, activity on the Sun and the effects of space weather on our terrestrial environment are high. At solar minimum, the sun may go many days with no sunspots visible. At maximum, there may be several hundred sunspots on any day.
What is space weather?
The term “space weather” was coined not long ago to describe the dynamic conditions in the Earth’s outer space environment, in the same way that “weather” and “climate” refer to conditions in Earth’s lower atmosphere. Space weather includes any and all conditions and events on the sun, in the solar wind, in near-Earth space and in our upper atmosphere that can affect space-borne and ground-based technological systems and through these, human life and endeavor. Heliophysics is the science of space weather.
Does the Sun cause space weather?
Looking at the sky with the naked eye, the sun seems static, placid, and constant. But our sun gives us more than just a steady stream of warmth and light. The sun regularly bathes Earth and the rest of our solar system in energy in the forms of light and electrically charged particles and magnetic fields. The resulting impacts are what we call space weather. The sun is a huge thermo-nuclear reactor, fusing hydrogen atoms into helium and producing million degree temperatures and intense magnetic fields. The outer layer of the sun near its surface is like a pot of boiling water, with bubbles of hot, electrified gas—electrons and protons in a fourth state of matter known as plasma—circulating up from the interior and bursting out into space. The steady stream of particles blowing away from the sun is known as the solar wind. Blustering at 800,000 to 5 million miles per hour, the solar wind carries a million tons of matter into space every second (that’s the mass of Utah’s Great Salt Lake) and reaches well beyond the solar system’s planets. Its speed, density and the magnetic fields associated with that plasma affect Earth’s protective magnetic shield in space (the magnetosphere).
Do space weather effects / solar storms affect Earth?
Modern society depends on a variety of technologies susceptible to the extremes of space weather. Strong electrical currents driven along the Earth’s surface during auroral events disrupt electric power grids and contribute to the corrosion of oil and gas pipelines. Changes in the ionosphere during geomagnetic storms interfere with high-frequency radio communications and Global Positioning System (GPS) navigation. During polar cap absorption events caused by solar protons, radio communications can be compromised for commercial airliners on transpolar crossing routes. Exposure of spacecraft to energetic particles during solar energetic particle events and radiation belt enhancements cause temporary operational anomalies, damage critical electronics, degrade solar arrays, and blind optical systems such as imagers and star trackers.
Human and robotic explorers across the solar system are also affected by solar activity. Research has shown, in a worst-case scenario, astronauts exposed to solar particle radiation can reach their permissible exposure limits within hours of the onset of an event. Surface-to-orbit and surface-to-surface communications are sensitive to space weather storms.
What are some real-world examples of space weather impacts?
- September 2, 1859, disruption of telegraph service.
- One of the best-known examples of space weather events is the collapse of the Hydro-Québec power network on March 13, 1989 due to geomagnetically induced currents (GICs). Caused by a transformer failure, this event led to a general blackout that lasted more than 9 hours and affected over 6 million people. The geomagnetic storm causing this event was itself the result of a CME ejected from the sun on March 9, 1989.
- Today, airlines fly over 7,500 polar routes per year. These routes take aircraft to latitudes where satellite communication cannot be used, and flight crews must rely instead on high-frequency (HF) radio to maintain communication with air traffic control, as required by federal regulation. During certain space weather events, solar energetic particles spiral down geomagnetic field lines in the polar regions, where they increase the density of ionized gas, which in turn affects the propagation of radio waves and can result in radio blackouts. These events can last for several days, during which time aircraft must be diverted to latitudes where satellite communications can be used.
No large Solar Energetic Particles events have happened during a manned space mission. However, such a large event happened on August 7, 1972, between the Apollo 16 and Apollo 17 lunar missions. The dose of particles would have hit an astronaut outside of Earth’s protective magnetic field, had this event happened during one of these missions, the effects could have been life threatening.
Do scientists expect a huge solar storm in 2013?
The sun goes through cycles of high and low activity that repeat approximately every 11 years. Solar minimum refers to the several Earth years when the number of sunspots is lowest; solar maximum occurs in the years when sunspots are most numerous. During solar maximum, activity on the sun and the possibility of space weather effects on our terrestrial environment is higher. The next solar maximum is expected in the 2013-2014 time frame. No current observations or data show any impending catastrophic solar event. In fact, scientists believe the intensity of the upcoming coming solar maximum will be similar to the previous maximum in 2002.
We have never been so well prepared for the onset of the next solar cycle. NASA maintains a fleet of Heliophysics spacecraft to monitor the sun, geospace, and the space environment between the sun and the Earth.
NASA cooperates with other U.S. agencies to enable new knowledge in studying the sun and its processes. To facilitate and enable this cooperation, NASA’s Heliophysics Division makes its vast research data sets and models publicly available online to industry, academia, and other civil and military space weather interests. Also provided are publicly available sites for citizen science and space situational awareness through various cell phone and e-tablet applications.
How long do space weather events usually last?
Solar storms can last only a few minutes to several hours but the affects of geomagnetic storms can linger in the Earth’s magnetosphere and atmosphere for days to weeks.
How are space weather events observed?
Scientists utilize a variety of ground- and space-based sensors and imaging systems to view activity at various depths in the solar atmosphere. Telescopes are used to detect visible light, ultraviolet light, gamma rays, and X rays. They use receivers and transmitters that detect the radio shock waves created when a CME crashes into the solar wind and produces a shock wave. Particle detectors to count ions and electrons, magnetometers record changes in magnetic fields, and UV and visible cameras observe auroral patterns above the Earth.
Are solar storms dangerous to us?
In an active part of the sun’s 11-year cycle of activity, those using telescopes equipped with special solar filters to peer at the sun – or photograph it – can see dark sunspots dotting the sun’s surface. Space observatories will detect short-lived but brilliant and powerful solar flares – intense bursts of radiation and our solar system’s largest explosive events – lasting minutes to hours on the sun’s surface. Occasional, powerful coronal mass ejections, or CMEs – giant bubbles of gas and magnetic fields from the sun, containing up to a billion tons of charged particles that can travel up to several million miles per hour – are released into the interplanetary medium. This solar material streams out through space, and sometimes strikes Earth. Is this dangerous? Should we be worried?
Solar storms aren’t dangerous to humans on Earth’s surface. These storms are awesome to contemplate, but they cannot harm our human bodies as long as we remain on the surface of Earth, where we’re protected by Earth’s blanket of atmosphere. Remember, there’s every reason to believe that storms on the sun have been happening for billions of years, since the sun and Earth came to be. If that’s so, then all life on Earth evolved under their influence.
What is the danger of a solar storm in space? Very high-energy particles, such as those carried by CMEs, can cause radiation poisoning to humans and other mammals. They would be dangerous to unshielded astronauts, say, astronauts traveling to the moon. Large doses could be fatal.
Still, solar storms – and their effects – are no problem for us on Earth’s surface. Earth’s atmosphere and magnetosphere protect our human bodies from the effects of solar flares.On the other hand … solar storms can be dangerous to our technologies. When a coronal mass ejection, or CME, strikes Earth’s atmosphere, it causes a temporary disturbance of the Earth’s magnetic field. The storm on the sun causes a type of storm on the Earth, known as a geomagnetic storm.
The most powerful solar storms send coronal mass ejections (CMEs), containing charged particles, into space. If Earth happens to be in the path of a CME, the charged particles can slam into our atmosphere, disrupt satellites in orbit and even cause them to fail, and bathe high-flying airplanes with radiation. They can disrupt telecommunications and navigation systems. They have the potential to affect power grids, and have been known to black out entire cities, even entire regions.
People talking about power failures from solar storms always point back to March 13, 1989, 31 years ago. A CME caused a power failure in Québec, as well as across parts of the northeastern U.S. In this event, the electrical supply was cut off to over 6 million people for nine hours.
But it’s possible for solar storms to be even more powerful than the one that caused the 1989 Québec and U.S. northeast blackout. The largest known solar flare took place on August 28, 1859. It was observed and recorded by Richard C. Carrington, and so it’s sometimes called the Carrington Event, or sometimes the 1859 Solar Superstorm. The accompanying coronal mass ejection (CME) traveled to Earth in only 17 hours, rather than the usual three or four days. The largest recorded geomagnetic storm occurred. Aurorae, or northern lights, were seen in many parts of the world. Telegraph systems throughout Europe and North America failed.
What would happen if such a powerful solar storm occurred today? And is such a powerful solar storm likely to occur again in our lifetimes? No one knows the answers to these questions with certainty.
But scientists have become increasingly aware of the possibility, especially since 2008, when Sten Odenwald and James Green published an article in the magazine Scientific American about the Carrington Event and possible consequences if such a powerful storm on the sun occurred today.
Scientists are asking more questions about solar storms and their consequences. For example, in 2012, scientists publishing in the journal Space Weather suggested that a 2001 power failure in New Zealand was caused by a solar storm. That result, if true, is particularly important because New Zealand is not at a high latitude (as Québec is, for example). It’s at a middle latitude, the same latitude as much of the United States. This 2012 study suggests that solar storm effects can reach into the more populous middle latitudes.
Scientists – for example at the Space Weather Prediction Center – continually monitor the sun, both from space and from Earth’s surface. When a solar storm with the potential to affect Earth takes place, they see it. After all, in order to affect us on Earth, the solar storm would have to happen on the side of the sun facing Earth. After such an event, it usually takes several days for the coronal mass ejection, or CME, to reach Earth. When a big CME is on its way, it is possible for satellites to shut their systems off briefly, and thereby remain safe. Likewise, with advance warning, Earth-based power grids can be reconfigured to provide extra grounding. And so on.
Are we in danger from a particularly huge solar storm, perhaps on the scale of the Carrington Event? Some believe we may be. That is why governments and scientists are beginning to pay more attention to this issue, with an eye to creating systems and procedures to help withstand such powerful effects from the sun.
Bottom line: Storms on the sun are a natural occurrence. They have been happening for billions of years. They are not dangerous to our human bodies on Earth’s surface. But they can affect some earthly technologies, such as power grids and satellites in orbit around Earth.