How Does the Sun Shine?

2017-07-14. Unlocking Mysteries in the Sun’s 11-Year Cycle. By Nicholas St. Fleur.

2017-06-23. Solving the Scorching Mystery of the Sun’s Erupting Plasma Jets. By Nicholas St. Fleur, The New York Times. 

2017-05-18. Humans Accidentally Made a Space Cocoon For Ourselves Out of Radio Waves. By Becky Ferreira for Motherboard. 

2017-02-17. How Space Weather Can Influence Elections on Earth. By Becky Ferreira for Motherboard. 

2016-09-15. The Geomagnetic Blitz of September 1941. By Jeffrey J. Love and Pierdavide Coïsson, for Earth and Space News EOS (AGU).

2016-02-24. Sun's Magnetic Fields Best at Forecasting Solar Cycle Peaks. By Aleida K. Higginson, EoS-Earth & Space Science News, AGU.

2015-12-07. Model of Solar Cycle's Impact on Climate Gets Upgrade. By Mark Zastrow, EoS Earth & Space Science News.

2015-11-06. White House Plan Focuses on Hazards from Solar Storms. By Randy Showstack, EoS Earth &  Space Science News, AGU.

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/stereo

2005 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





 

Articles from 2001–present

See Chinese New Year dragon on the Sun at the Space Weather website.

Solar Dynamics Observatory (SDO) movie of "coronal rain" on the Sun.