EF4C. Stay Current—How Does the Sun Shine?

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2024-12-12. Sun-like stars produce superflares roughly once per century. By Valeriy Vasilyev et al, Science. Editor’s Summary: Solar flares are bright, transient, multiwavelength emissions from active regions on the Sun. The most intense directly observed solar flares release energies of about 10³² erg. It is unclear whether the Sun can produce more intense flares than that or how often they might occur. Vasilyev et al. investigated brightness measurements of 56,000 Sun-like stars observed by the Kepler space telescope. They identified almost 3000 bright stellar flares with energies of about 10³⁴ to 10³⁵ erg, which are called superflares. The occurrence rate is about one superflare per star per century. If the Sun behaves like the stars in this sample, then it could produce superflares at a similar rate. —Keith T. Smith. Full article at https://www.science.org/doi/10.1126/science.adl5441.

2024-10-27. First Images of the Sun’s Flares Released From a New Space Telescope. By Katrina Miller, The New York Times. Excerpt: Before the northern lights fill the night sky on Earth with their eerie neon glow, a blast of electrified gas flares up from the sun’s surface. And scientists are now getting a powerful new view of how those ejections move through the corona, the sun’s tempestuous outer atmosphere. On Tuesday, the National Oceanic and Atmospheric Administration unveiled the first imagery from its newest telescope in space. Meteorologists will use pictures from the device to help them better forecast space weather, including when you can expect to see auroras. The new instrument is called the Compact Coronagraph, or CCOR-1. It launched in June aboard GOES-19, the newest of NOAA’s fleet of weather satellites. The coronagraph can continuously monitor the sun, and it will send data to scientists on the ground every 15 minutes. …Earlier this month, NASA and NOAA announced that the sun had reached a peak in activity, which fluctuates in an 11-year cycle. A heightened number of solar storms could continue for the next year. That makes it ever important for space weather forecasters to stay prepared, lest a particularly powerful blast of solar material knock out systems across a large portion of the world…. Full article with movie of coronal mass ejection at https://www.nytimes.com/2024/10/27/science/solar-flare-telescope-sun.html.

2023-12-04. Protecting Power Grids from Space Weather. [https://eos.org/research-spotlights/protecting-power-grids-from-space-weather] By Rachel Fritts, Eos/AGU. Excerpt: Activity from the Sun, such as solar flares, can cause fluctuations in Earth’s geomagnetic field that send electrical currents flowing through power grids. These geomagnetically induced currents (GICs) can cause problems ranging from temporary voltage instability to widespread blackouts to reduced life spans for transformers. It is therefore important to develop effective mitigation strategies that protect against GIC-induced power disruptions while maintaining power to consumers. Suggested solutions have included installing equipment such as capacitors to block GICs and making changes to network configurations. Mac Manus et al. worked with the energy company Transpower New Zealand Ltd. to test four mitigation strategies that could be used throughout the North and South Islands of New Zealand. The team did this by …modeling potential mitigation responses. …Working with Transpower, the researchers found that the mitigation strategy that best balanced effectiveness and practicality reduced the effects of GICs by 16% with a targeted disconnection of just 24 lines. Transpower has adopted this as the new operational procedure to manage space weather events. …the group determined that installing capacitor blocking devices on 14 specific transformers could reduce GICs by another 16%. … (Space Weather, https://doi.org/10.1029/2023SW003533, 2023)

2023-09-15. Peak solar activity is arriving sooner than expected, reaching levels not seen in 20 years. [https://www.science.org/content/article/peak-solar-activity-arriving-sooner-expected-reaching-levels-not-seen-20-years] By ZACK SAVITSKY, Science. Excerpt: In 2019, as the Sun approached a minimum in its 11-year cycle of magnetic activity, a dozen scientists assembled for a traditional exercise: forecasting the next peak. Now, a few years into the Sun’s resurgence, it’s becoming clear that the official prediction from the panel, convened by NASA, the National Oceanic and Atmospheric Administration (NOAA), and the International Space Environment Service (ISES), missed the mark. The Sun’s activity has already surpassed the forecast, reaching levels not seen in 20 years, and solar maximum may arrive within the next year, months ahead of its presumed schedule….

2023-07-20. Magnetic Tangles Drive Solar Wind. [https://eos.org/articles/magnetic-tangles-drive-solar-wind] By atthew R. Francis, Eos/AGU. Excerpt: Though the effects of solar wind are well documented, what causes it has been a mystery for more than 50 years. Now, thanks to a solar close-up, some researchers think the energy behind the flow of particles comes from the Sun’s own magnetic fields snapping together. The process, known as reconnection, may illuminate not only solar wind but winds from other stars as well as the behavior of comets and planetary atmospheres. In part to solve the solar wind mystery—and perhaps learn ways to spot solar storms before they form—researchers developed NASA’s Parker Solar Probe, which launched in 2018 and has been flying in ever-closer orbits to the Sun. …Reconnection occurs in plasmas when magnetic fields pointing in opposite directions cancel out, rapidly dumping their energy into the surrounding electrons and ions. A simplified picture would be taking two bar magnets pointed in opposite directions and letting them snap together: The noise of their collision is analogous to reconnection energy release. In the solar corona, this process happens when the magnetic fields that turned back toward the Sun come into proximity with those stretching out into the solar system, and the energy released is dumped into the charged particles that make up the solar wind….

2023-06-07. Parker Solar Probe flies into the fast solar wind and finds its source. [https://news.berkeley.edu/2023/06/07/parker-solar-probe-flies-into-the-fast-solar-wind-and-finds-its-source/] By Robert Sanders, UC Berkeley News. Excerpt: NASA’s Parker Solar Probe has flown close enough to the sun to detect the fine structure of the solar wind close to where it is generated at the sun’s surface, revealing details that are lost as the wind exits the corona as a uniform blast of charged particles. It’s like seeing jets of water emanating from a showerhead through the blast of water hitting you in the face. In a paper to be published this week in the journal Nature, a team of scientists led by Stuart D. Bale, a professor of physics at the University of California, Berkeley, and James Drake of the University of Maryland-College Park, report that the Parker Solar Probe has detected streams of high-energy particles that match the supergranulation flows within coronal holes, which suggests that these are the regions where the so-called “fast” solar wind originates. …The probe was launched in 2018 primarily to resolve two conflicting explanations for the origin of the high-energy particles that comprise the solar wind: magnetic reconnection or acceleration by plasma or Alfvén waves. …“The big conclusion is that it’s magnetic reconnection within these funnel structures that’s providing the energy source of the fast solar wind,” Bale said. …The Parker Solar Probe won’t be able to get any closer to the sun than about 8.8 solar radii above the surface — about 4 million miles — without frying its instruments. Bale expects to solidify the team’s conclusions with data from that altitude, …. See also New York Times article How Solar Wind Flows From the Sun Like Water From a Shower Head.

2022-10-25. Converging Toward Solutions to Grand Challenges. [https://eos.org/opinions/converging-toward-solutions-to-grand-challenges] By Ryan McGranaghan,  Adam Kellerman and  Mark Olson, Eos/AGU. Excerpt: Electrical power grids, on which we all depend, comprise numerous interconnected components, including generators, transformers, and transmission and distribution lines…. These massive and truly complex systems function at the whim of myriad natural forces and the vicissitudes of human behavior that can reduce grid reliability or knock out operation altogether. Creating a power grid that is resilient to these forces is a national-scale societal challenge, one that cannot be addressed by a single sector or discipline. Meeting this and other grand, sociotechnical challenges requires convergence, the merging of innovative ideas, approaches, and technologies from a wide range of sectors and expertise. With convergence comes a new spectrum of challenges involving how we work across disciplinary lines, collaborate meaningfully in large groups, and develop healthy—meaning open, participatory, and resilient—connections among diverse stakeholders. …The Convergence Hub for the Exploration of Space Science (CHESS) is a research project working to develop best practices for convergence research in the context of studying and predicting space weather. Recently, members of the CHESS team and others held a three-part workshop involving a simulated extreme space weather storm with impacts on power grid resilience and socioeconomic conditions, activities designed to highlight knowledge gaps apparent from the simulation, and group work to develop potential solutions to the gaps identified.…

2022-10-07. Space Raindrops Splashing on Earth’s Magnetic Umbrella. [https://eos.org/features/space-raindrops-splashing-on-earths-magnetic-umbrella] By Laura Vuorinen,  Adrian LaMoury,  Emmanuel Masongsong and  Heli Hietala, Eos/AGU. Excerpt: Though not as damaging as extreme space weather events, showers of plasma jets hit Earth’s magnetic shield every day—yet we’re only beginning to understand their effects.…The famed Carrington event of 1859, the strongest coronal mass ejection ever observed, produced auroras as far south as Mexico and Cuba, with many people reporting the night sky to be as bright as day. The massive compression of the magnetosphere during the event caused severe and widespread damage to telegraph systems, resulting in electrocutions of operators and outbreaks of fires. If such an event were to happen again today, the disruption to our technology and infrastructure would be profound, with costs estimated to be in the trillions of dollars. From GPS failure to widespread electrical power outages, a Carrington-size coronal mass ejection could bring the world to a standstill. It’s hard to imagine a world where telephone and Internet communications are suddenly cut off, let alone one without power to charge devices! …Fortunately, events of this intensity are very infrequent within the span of a human lifetime—they are among the least common natural disasters. …Magnetosheath jets rain on Earth’s magnetosphere every day [Plaschke et al., 2018]. As the solar wind is processed, slowed down, and compressed at the bow shock, jets can sporadically emerge, influenced by the structure of the shock itself.…

2022-08-25. Brighter Skies Ahead—As solar max approaches, new tech is on call. [https://eos.org/agu-news/brighter-skies-ahead] By Heather Goss, Eos/AGU. Excerpt: …An impressive cadre of Sun-targeted missions has recently come online to replace or support an aging fleet of spacecraft, just as solar max is about to set in. …In February 2020, Solar Orbiter launched from Florida, carrying 10 state-of-the-art instruments to make the closest ever observations of the Sun. Daniele Telloni and colleagues, in “A New Journey Around (and Around) the Sun,” describe for us “the groundbreaking observations that Solar Orbiter has made already,” such as the “short-lived, small-scale flickering bright spots, nicknamed ‘campfires,’ in the solar corona.” Not only will this joint European Space Agency–NASA mission shed new light on the unsolved mysteries of the Sun, but also it’s revealing a new side of Venus from its 2020 flyby. …in our next feature, “Shake, Rattle, and Probe.” Helioseismology is a burgeoning discipline that allows physicists to better understand the structure of our star. …“11 Discoveries Awaiting Us at Solar Max,” get excited about peering inside coronal mass ejections, creating “Sun to mud” predictions, and better understanding magnetic fields throughout our solar system.…

2020-05-11. Space Weather Forecasting Takes Inspiration from Meteorology. By Sarah Stanley, Eos/AGU. Excerpt: Every so often, the Sun unleashes powerful bursts of plasma particles and magnetic field structures toward Earth. These solar storms can wreak havoc on power grids [https://eos.org/features/the-geomagnetic-blitz-of-september-1941], satellites [https://eos.org/editor-highlights/space-traffic-management-better-space-weather-forecasts-needed], and other infrastructure, but they are difficult to predict more than a few days in advance. In a new review, Dikpati and McIntosh [https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018SW002109] showcase mounting evidence that solar storms arise from solar Rossby waves, a type of wave associated with rotating fluids. Just as the 1939 discovery of Rossby waves [https://www.weather.gov/jetstream/longshort] in Earth’s atmosphere paved the way to accurate weather prediction, Rossby waves in the Sun could be key to predicting disruptive space weather in time to prepare for it. On Earth, atmospheric Rossby waves arise from the planet’s rotation, and these large-scale meandering features help transport warm air toward the poles and cold air toward the tropics. Earth’s Rossby waves sometimes have extreme effects, such as those from 2019’s polar vortex…. [https://eos.org/research-spotlights/space-weather-forecasting-takes-inspiration-from-meteorology] 

2017-07-14. Unlocking Mysteries in the Sun’s 11-Year Cycle. By Nicholas St. Fleur. Excerpt: According to a study published Thursday in the journal Science, our beloved star can be classified as an ordinary “solar-type” star, meaning that the internal processes that control its activity are similar to those seen in many other nearby stars. The sun goes through an 11-year cycle where its magnetic poles flip — imagine the north and south poles on Earth changing place — and during this time the sun’s activity changes between subdued and tumultuous. When activity is low, it is known as solar minimum, and when activity is high, it is known as solar maximum. As the sun nears solar maximum and its activity cycle ramps up, its surface gets covered in sunspots, which are ephemeral dark marks created by strong magnetic activity. “Above sunspots you have complex structures that trigger dynamic phenomenons, eruptions that are like volcanoes,” said Antoine Strugarek, a solar physicist at the French Alternative Energies and Atomic Energy Commission and at the University of Montreal. “Those eruptions can impact our Earth.” …In a study published Friday in the journal Science Advances, Dr. Morgan found that when the sun is at solar minimum, the quiet corona measures around 1.4 million degrees Celsius. But at solar maximum it jumps to around 1.8 million degrees. Dr. Morgan said he was not sure why the entire corona, including the areas not above a sunspot, heat up as the sun’s activity increases. “The solar corona remains a mystery,” he said. “But we are getting far better at measuring what it’s doing and that’s enabling us to start to understand it.”…. https://www.nytimes.com/2017/07/14/science/sun-cycles-solar-maximum-minimum-corona.html

2017-06-23. Solving the Scorching Mystery of the Sun’s Erupting Plasma Jets. By Nicholas St. Fleur, The New York Times. Excerpt: Spiky bursts of plasma called spicules swirl around the surface of the sun. Millions erupt every moment, spurting solar material some 6,000 miles high at speeds of about 60 miles per second. “These things are very violent,” said Bart De Pontieu, a research scientist with Lockheed Martin Solar and Astrophysics Lab in Palo Alto, Calif. “The gas in spicules is about 10,000 degrees and they travel the length of California in just a minute or so.” Scientists have studied spicules for decades, but were not sure how the plasma jets formed. Now, Dr. De Pontieu and his colleagues think they have solved the searing mystery. They published their findings Thursday in the journal Science. …they created a computer simulation that reconstructed the conditions between the sun’s surface and its atmosphere, where spicules form. Powerful magnetic fields are created in the interior of the sun. There, the high density keeps them tangled and tamed. But near the surface, the magnetic fields can use neutral particles, atoms that do not carry an electric charge, to diffuse into the sun’s atmosphere. The fields enter a reddish layer called the chromosphere where their violent nature is unleashed. “It’s a sling shot effect,” said Mats Carlsson, a professor of astrophysics at the University of Oslo in Norway, and co-author of the paper. The density in the chromosphere is significantly lower than in the sun’s interior, so the magnetic fields are no longer suppressed and are able to straighten out. As they unwind and release their tension, they fling hot plasma at incredible speeds, creating the spicules. The spicules surge thousands of miles high, passing through the chromosphere and into the sun’s corona before collapsing….  https://www.nytimes.com/2017/06/23/science/sun-plasma-jets-spicules.html

2017-05-18. Humans Accidentally Made a Space Cocoon For Ourselves Out of Radio Waves. By Becky Ferreira for Motherboard. Excerpt: Humans have accidentally created a protective bubble around Earth by using very low frequency (VLF) radio transmissions to contact submarines in the ocean. It sounds nuts, but according to recent research published in Space Science Reviews, underwater communication through VLF channels has an outer space dimension. …Satellites in certain high-altitude orbits, such as NASA’s particle-watching Van Allen Probes, have observed these VLF ripples creating an “impenetrable boundary,” a phrase coined by study co-author Dan Baker, director of the University of Colorado’s Laboratory for Atmospheric and Space Physics. This doesn’t mean impenetrable to spacecraft or asteroids, per se, but rather to potentially harmful particle showers created by turbulent space weather. …The boundary extends out to the inner edge of the Van Allen radiation belts, which are bands of charged particles created from the clash of the solar wind against Earth’s magnetic field. The VLF bubble might actually be pushing the Van Allen belts farther into space, suggests Baker, considering that they have receded farther from Earth since the 1960s, when VLF use was not as widespread….  https://motherboard.vice.com/en_us/article/nasa-space-weather-earth-cocoon-van-allen

2017-02-17. How Space Weather Can Influence Elections on Earth. By Becky Ferreira for Motherboard. Excerpt: The real alien voter fraud is genuinely coming from outside our planet. …The Sun, which is emphatically not registered to vote, dabbles in casting ballots on Earth, according to a presentation given by Bharat Bhuva, a professor of electrical engineering at Vanderbilt University, on Friday morning at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston. Bhuva specializes in assessing the risk of space weather damaging electrical systems on and around Earth, including electronic voting systems. He brought up one instance of a federal election held in the city of Schaerbeek, Belgium in 2003, in which one of the candidates ended up with 4,096 extra votes. “Everything was going fine, but then suddenly, there were an additional 4,000 votes cast […] People were surprised and asked, ‘how did this happen?'” The culprit was not voter fraud or hacked machines. It was most likely a single event upset (SEU), a term describing the fallout of an ionizing particle bouncing off a vulnerable node in the machine’s register, causing it to flip a bit, and log the additional votes. The Sun may not have been the direct source of the particle—cosmic rays from outside the solar system are also in the mix—but solar-influenced space weather certainly contributes to these SEUs….  https://motherboard.vice.com/en_us/article/space-weather-cosmic-rays-voting-aaas

2016-09-15. The Geomagnetic Blitz of September 1941. By Jeffrey J. Love and Pierdavide Coïsson, for Earth and Space News EOS (AGU). Excerpt: Seventy-five years ago next week, a massive geomagnetic storm disrupted electrical power, interrupted radio broadcasts, and illuminated the night sky in a World War II battle theater. …Auroras danced across the night sky as voltage surged in power grid lines. A radio blackout interrupted fan enjoyment of a baseball game, while another radio program was interrupted by private phone conversations. …And far away in the North Atlantic, the illuminated night sky exposed an Allied convoy to German attack. …On the basis of daily sunspot reports supplied by the U.S. Naval Observatory, the Department of Terrestrial Magnetism at the Carnegie Institution of Washington formally issued a warning to radio operators that they could expect significant disturbances to ionospheric and geomagnetic conditions beginning on about 18 September…. This prediction, which turned out to be accurate, is a noteworthy development in the historical development of methods for reliably forecasting space weather. Less than 20 hours after the flare was reported by Greenwich, a magnetic storm commenced at 0412 UT on 18 September with the arrival at Earth of a coronal mass ejection. …On 18–19 September 1941, the Moon was nearly new, ideal for seeing the auroral light…. The observer in charge at the Cheltenham, Md., observatory reported a brilliant auroral display of rays and moving drapery of pink, green, and lavender. He also described an auroral corona, where light appears to stream down from directly overhead, a phenomenon rarely seen at midcontinental latitudes. …Weather Service observers reported seeing auroras in New Mexico [Cameron, 1941]. …at 19:45 and 19:50 UT, the Pennsylvania Water and Power Company recorded uncontrolled voltage variations in transmission lines connecting generating plants on the Susquehanna River with Baltimore and Washington. At the moment when the auroral brilliance was greatest, system transformers vibrated and groaned as a result of geomagnetically induced currents….  https://eos.org/features/the-geomagnetic-blitz-of-september-1941  See also  Scientists Get First Glimpse of Solar Wind as It Forms.

2016-02-24. Sun’s Magnetic Fields Best at Forecasting Solar Cycle Peaks. By Aleida K. Higginson, EoS-Earth & Space Science News, AGU. Excerpt: Solar activity level rises and falls every 11 years. The most recent maximum in solar activity level, the 24th since recording began in 1755, was the weakest in almost 100 years and peaked in early 2014.  Solar activity refers to dark regions on the surface of the Sun called sunspots, where the Sun’s magnetic field has become tangled. They can produce sudden explosions of energy in the form of intense radiation and energetic particles. Sometimes, these regions will even kick out a portion of the tangled magnetic field and send it hurdling into space in an event called a coronal mass ejection. When these bursts of radiation, particles, and magnetic field reach Earth, they cause geomagnetic storms, which can interfere with communication satellites and power grids on the ground. These events could also be harmful to astronauts traveling to Mars, exposing them to possibly deadly amounts of radiation. …a new study by Pesnell compares all of the predictions to determine which forecasts were the most accurate. … For past solar cycles, models using geomagnetic activity level made more accurate predictions, but this accuracy may be due to the fact that solar polar magnetic field data were scarce or unreliable. This time, for solar cycle 24, the models using polar magnetic fields made the best predictions by far.  …solar cycle 25, slated to begin as early as 2020…. (Space Weather, doi:10.1002/2015SW001304, 2016)…  https://eos.org/research-spotlights/suns-magnetic-fields-best-at-forecasting-solar-cycle-peaks

2015-12-07. Model of Solar Cycle’s Impact on Climate Gets Upgrade. By Mark Zastrow, EoS Earth & Space Science News. xcerpt: …Over the course of the 11-year cycle, the rotation of the Sun slowly twists its magnetic field into knots, creating dark sunspots. Although the overall brightness of the Sun varies by only 0.1%, the twisted bundles of magnetic energy can boost its ultraviolet (UV) radiation by 4%–8% at the solar cycle’s peak. These powerful UV rays trigger chemical reactions in the stratosphere that bind oxygen atoms and molecules to form ozone. Since ozone itself is a good absorber of UV radiation, it can heat the stratosphere near the equator, which affects the winds that circle the globe. Increased solar activity also excites Earth’s magnetic field, sending high-energy particles hurtling into the upper atmosphere. During the long polar night, this can generate large amounts of the nitrogen compounds nitric oxide (NO) and nitrogen dioxide (NO2), which eventually descend into the stratosphere and destroy ozone. To study the effects of these often-competing processes, scientists construct simulations using models such as the Whole Atmosphere Community Climate Model (WACCM) produced by the National Center for Atmospheric Research….  https://eos.org/research-spotlights/model-of-solar-cycles-impact-on-climate-gets-upgrade

2015-11-06. White House Plan Focuses on Hazards from Solar Storms. By Randy Showstack, EoS Earth &  Space Science News, AGU. Excerpt: Space weather has its day in the Sun, with the administration issuing a new strategy and action plan to increase protection from damaging solar emissions. …Space weather events occur when outbursts from the Sun, such as solar flares, solar energetic particles, and coronal mass ejections, collide with Earth’s magnetic field. Although many of these events are harmless, some are powerful enough to cause havoc by disrupting critical technology. Speakers at the forum referred to a 1989 geomagnetic storm that cut electricity to 6 million Canadians for 9 hours and to the 1859 “Carrington” event, the largest documented series of geomagnetic storms from the Sun to have struck Earth….  https://eos.org/articles/white-house-plan-focuses-on-hazards-from-solar-storms

2014-07-01. A Solar Show With Mixed Reviews. Excerpt: …the maximum — the peak of the 11-year sunspot cycle, when the sun erupts with solar flares and energetic bursts of electrons and protons — may have already passed. As solar maximums go, this has been a tepid one, particularly when measured against some predictions that it would be ferocious; it has been called a “minimax.” But neither does it rival a quiet period in the second half of the 1600s that coincided with the onset of the Little Ice Age, a prolonged chill in Europe. …“I think the general consensus is that we’ve passed the peak,” said C. Alex Young, a solar astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md. But he added that some of the biggest solar storms in history occurred on the downward side of the solar cycle, and even a weak cycle can generate ferocious outbursts. “I think the expectation right now is we might see another burst of this activity five or six months from now,” Dr. Young said. “We might still have some big events.”… http://www.nytimes.com/2014/07/01/science/a-solar-show-with-mixed-reviews.html. By Kenneth Chang, The New York Times.

2013-01-08.  Solar Variability and Terrestrial Climate | NASA Science News. Excerpt: …In the galactic scheme of things, the Sun is a remarkably constant star.  While some stars exhibit dramatic pulsations, wildly yo-yoing in size and brightness, and sometimes even exploding, the luminosity of our own sun varies a measly 0.1% over the course of the 11-year solar cycle.  There is, however, a dawning realization among researchers that even these apparently tiny variations can have a significant effect on terrestrial climate. A new report issued by the National Research Council (NRC), “The Effects of Solar Variability on Earth’s Climate” [at http://www.nap.edu/catalog.php?record_id=13519] lays out some of the surprisingly complex ways that solar activity can make itself felt on our planet. …Greg Kopp of the Laboratory for Atmospheric and Space Physics at the University of Colorado, pointed out that … “Even typical short term variations of 0.1% in incident irradiance exceed all other energy sources (such as natural radioactivity in Earth’s core) combined,” he says. Of particular importance is the sun’s extreme ultraviolet (EUV) radiation, which …varies not by a minuscule 0.1%, but by whopping factors of 10 or more.  This can strongly affect the chemistry and thermal structure of the upper atmosphere.  …In recent years, researchers have considered the possibility that the sun plays a role in global warming. After all, the sun is the main source of heat for our planet. The NRC report suggests, however, that the influence of solar variability is more regional than global…. Read the full article: http://science.nasa.gov/science-news/science-at-nasa/2013/08jan_sunclimate/

2010 Summer. Probing the Solar Plasma. By Kathleen M. Wong, Science Matters @ Berkeley.  Excerpt: …“From just outside earth’s atmosphere all the way to the part of the sun you see during the day, is all plasma,” says Stuart Bale. A Berkeley professor of physics and director of the university’s Space Sciences Laboratory, Bale studies the plasmas that stream from stars and suffuse entire galaxies.
…Bale has submitted a proposal for an experiment that will study the acceleration and heating of the solar wind. The wind originates as plasma evaporating from the sun’s relatively cool 5,000 to 6,000 degree Celsius surface. As it expands and rises into the corona, the radiant solar “atmosphere” only visible during a total solar eclipse, this plasma grows hotter and faster until it is roaring through the solar system at more than a million kilometers per hour.
…“There has to be some collisionless process that’s heating the plasma. There has to be some place for that energy cascading into smaller and smaller scales to go,” Bale says. To observe that transfer of heat, Bale has proposed to measure the electromagnetic fields in the corona and the temperature at the same time. In this way, he can link the behavior of the fields to the transfer of heat.
…Though the theory seems to fit, details of the process aren’t known. The information gleaned from the experiment will then help characterize the physics of black hole accretion disks, galaxy clusters, and other stars. “Heating coronas is a universal astrophysical problem,” Bale says.

2009 Feb 11. Solar Dynamics Observatory successfully launched Feb 11. Mission Science Objectives–The scientific goals of the SDO Project are to improve our understanding of seven science questions:
1. What mechanisms drive the quasi-periodic 11-year cycle of solar activity?
2. How is active region magnetic flux synthesized, concentrated, and dispersed across the solar surface?
3. How does magnetic reconnection on small scales reorganize the large-scale field topology and current systems and how significant is it in heating the corona and accelerating the solar wind?
4. Where do the observed variations in the Sun’s EUV spectral irradiance arise, and how do they relate to the magnetic activity cycles?
5. What magnetic field configurations lead to the CMEs, filament eruptions, and flares that produce energetic particles and radiation?
6. Can the structure and dynamics of the solar wind near Earth be determined from the magnetic field configuration and atmospheric structure near the solar surface?
7. When will activity occur, and is it possible to make accurate and reliable forecasts of space weather and climate?

2009 Sep 17. Solar Cycle Driven by More than Sunspots. NSF Press Release 09-171. Excerpt: Challenging conventional wisdom, new research finds that the number of sunspots provides an incomplete measure of changes in the Sun’s impact on Earth over the course of the 11-year solar cycle. The study, led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Michigan, finds that Earth was bombarded last year with high levels of solar energy at a time when the Sun was in an unusually quiet phase and sunspots had virtually disappeared….

2009 Jul 20. Is the Sun Missing Its Spots? [photos show sunspots near solar maximum on July 19, 2000, and near solar minimum on March 18, 2009. Some global warming skeptics speculate that the Sun may be on the verge of an extended slumber.] By Kenneth Chang, The NY Times. Excerpt: The Sun is still blank (mostly).
Ever since Samuel Heinrich Schwabe, a German astronomer, first noted in 1843 that sunspots burgeon and wane over a roughly 11-year cycle, scientists have carefully watched the Sun’s activity. In the latest lull, the Sun should have reached its calmest, least pockmarked state last fall.
Indeed, last year marked the blankest year of the Sun in the last half-century – 266 days with not a single sunspot visible from Earth. Then, in the first four months of 2009, the Sun became even more blank, the pace of sunspots slowing more….

2009 May 29. New Solar Cycle Prediction. By Dr. Tony Phillips, Science@NASA. An international panel of experts has issued a new prediction for the solar cycle that takes into account the surprisingly deep solar minimum of 2008-2009. Find out when they think solar maximum will return.

2007 April 24. NASA Releases 3D Images of Sun. By THE ASSOCIATED PRESS. Excerpt: GREENBELT, Md. (AP) — NASA released the first three-dimensional images of the sun Monday, saying the photos taken from twin spacecraft may lead to better predictions of solar eruptions that can affect communications and power lines on Earth. … ‘Wow!”’ scientist Simon Plunkett said as he explained the images to a room full of journalists and scientists wearing 3D glasses. The images from the STEREO spacecraft (for Solar Terrestrial Relations Observatory) are available on the Internet and at museums and science centers nationwide. The twin spacecraft, launched in October, are orbiting the Sun, one slightly ahead of the Earth and one behind. The separation, just like the distance between our two eyes, provides the depth perception that allows the 3D images to be obtained. That depth perception is also particularly helpful for studying a type of solar eruption called a coronal mass ejection. Along with overloading power lines and disrupting satellite communications, the eruptions can endanger astronauts on spacewalks. Scientists would like to improve predictions of the arrival time from the current day or so to a few hours, said Russell Howard, principal investigator for the Naval Research Laboratory project. Seehttp://www.nasa.gov/stereo2005 May 24. Solar Fireworks Signal New Space Weather Mystery. NASA RELEASE 05-132. The most intense burst of solar radiation in five decades accompanied a large solar flare on January 20. It shook space weather theory and highlighted the need for new forecasting techniques, according to several presentations at the American Geophysical Union (AGU) meeting this week in New Orleans. The solar flare, which occurred at 2 a.m. EST, tripped radiation monitors all over the planet and scrambled detectors onTspacecraft. The shower of energetic protons came minutes after the first sign of the flare. This flare was an extreme example of the type of radiation storm that arrives too quickly to warn interplanetary astronauts. “This flare produced the largest solar radiation signal on the ground in nearly 50 years,” said Dr. Richard Mewaldt of the California Institute of Technology, Pasadena, Calif. … “But we were really surprised when we saw how fast the particles reached their peak intensity and arrived at Earth.” Normally it takes two or more hours for a dangerous proton shower to reach maximum intensity at Earth after a solar flare. The particles from the January 20 flare peaked about 15 minutes after the first sign. …The Transitional Region and Coronal Explorer (TRACE) … has identified a possible source of the magnetic stress that causes solar flares. The sunspots that give off the very largest (X-class) flares appear to rotate in the days around the flare. “This rotation stretches and twists the magnetic field lines over the sunspots”, Nightingale said. “We have seen it before virtually every X-flare that TRACE has observed since it was launched and more than half of all flares in that time.” However, rotating sunspots are not the whole story. The unique flare came at the end of a string of five other very large flares from the same sunspot group, and no one knows why this one produced more sudden high energy particles than the first four. “It means we really don’t understand how the sun works,” Lin said. “We need to continue to operate and exploit our fleet of solar-observing spacecraft to identify how it works.” 

2005

24 May 2005. Solar Fireworks Signal New Space Weather Mystery. NASA RELEASE 05-132. The most intense burst of solar radiation in five decades accompanied a large solar flare on January 20. It shook space weather theory and highlighted the need for new forecasting techniques, according to several presentations at the American Geophysical Union (AGU) meeting this week in New Orleans. The solar flare, which occurred at 2 a.m. EST, tripped radiation monitors all over the planet and scrambled detectors on spacecraft. The shower of energetic protons came minutes after the first sign of the flare. This flare was an extreme example of the type of radiation storm that arrives too quickly to warn interplanetary astronauts. “This flare produced the largest solar radiation signal on the ground in nearly 50 years,” said Dr. Richard Mewaldt of the California Institute of Technology, Pasadena, Calif. … “But we were really surprised when we saw how fast the particles reached their peak intensity and arrived at Earth.” Normally it takes two or more hours for a dangerous proton shower to reach maximum intensity at Earth after a solar flare. The particles from the January 20 flare peaked about 15 minutes after the first sign. …The Transitional Region and Coronal Explorer (TRACE) … has identified a possible source of the magnetic stress that causes solar flares. The sunspots that give off the very largest (X-class) flares appear to rotate in the days around the flare. “This rotation stretches and twists the magnetic field lines over the sunspots”, Nightingale said. “We have seen it before virtually every X-flare that TRACE has observed since it was launched and more than half of all flares in that time.” However, rotating sunspots are not the whole story. The unique flare came at the end of a string of five other very large flares from the same sunspot group, and no one knows why this one produced more sudden high energy particles than the first four. “It means we really don’t understand how the sun works,” Lin said. “We need to continue to operate and exploit our fleet of solar-observing spacecraft to identify how it works.”

2004

18 October 2004. Science@NASA. Solar physicist David Hathaway has been checking the sun every day since 1998, and every day for six years there have been sunspots. Sunspots are planet-sized “islands” on the surface of the sun. They are dark, cool, powerfully magnetized, and fleeting: a typical sunspot lasts only a few days or weeks before it breaks up. As soon as one disappears, however, another emerges to take its place. Even during the lowest ebb of solar activity, you can usually find one or two spots on the sun. But when Hathaway looked on Jan. 28, 2004, there were none. The sun was utterly blank. It happened again last week, twice, on Oct. 11th and 12th. There were no sunspots. “This is a sign,” says Hathaway, “that the solar minimum is coming, and it’s coming sooner than we expected.

2001

12 July 2001. GREATER SOLAR ACTIVITY MAY BRING U.S. MORE GRAY DAYS — Also here