AC3C. Stay Current—Cosmic Engines

A Changing Cosmos Cover

Staying current for Chapter 3

{ A Changing Cosmos Contents }

Articles from 2005–present

2024-01-04. Mapping the Moon to Shield Astronauts from Radiation. [] By Sierra Bouchér, Eos/AGU. Excerpt: In October 1989, the Sun spit a blast of high-energy particles into the solar system. Earth’s protective magnetic field kept us safe, but the Moon received an intense dose: More than 8 times the radiation received by plant workers during the Chernobyl nuclear disaster scorched the barren lunar surface. As NASA’s Artemis III mission prepares to return explorers to the Moon in 2025, scientists are working to protect them from this kind of unpredictable outburst from the Sun and other radiation from deep space. To do this, they’re turning to the Moon’s natural barriers. By mapping the topography of the lunar surface, researchers have calculated the shielding potential of each mountain range, crater wall, and shadowed slope near the south pole—Artemis III’s target. Their work will guide decisionmaking for the landing location of this mission and beyond….

2022-08-10. Nearby star’s midlife crisis illuminates the future of our own Sun. [] By Zack Savitsky, Science Magazine. Excerpt: Long magnetic lull on star mimics the Maunder Minimum, when the Sun’s spots largely disappeared 400 years ago. Soon after European astronomers developed the first telescopes at the start of the 17th century, they observed dark spots speckling the Sun’s surface. They also handed their modern successors a mystery. From about 1645 to 1715, the spots, now known to be indicators of solar activity, all but disappeared. Gathering sunspot counts and other historical observations, astronomer John Eddy concluded nearly 50 years ago that the Sun had essentially taken a 70-year nap, which he called the Maunder Minimum after an astronomer couple who had previously studied it. Now, it appears the Sun is not the only star that takes long naps. By building a decades-long record of observations of a few dozen stars at specific wavelengths that trace stellar activity, a team of astronomers has identified another star going through its own Maunder Minimum period. …The finding, reported in a preprint last month on arXiv, could help explain what triggered the Sun’s strange behavior 400 years ago and suggests more such episodes are likely. …van Saders says…that such events are an occasional symptom of a critical transition in the magnetic field of Sun-like stars about halfway through their lifetime—a midlife crisis of sorts. Some astronomers speculate that the Sun’s transition helped favor the emergence of life on Earth…. Scientists have known for decades that our Sun’s activity surges and ebbs on a roughly 11-year cycle, which corresponds to how often its magnetic poles flip their orientation. During a solar maximum, sunspots proliferate, marking weak points in the magnetic field, where plasma from the Sun’s atmosphere can lash out in violent loops. Astronomers have spotted young Sun-like stars with similar cycles, and older ones that have totally stable activity. But no one had spotted a cycling star suddenly turning flat.…

2022-06-10. Why Did Sunspots Disappear for 70 Years? Nearby Star Holds Clues. [] By Kimberly M. S. Cartier, Eos/AGU. Excerpt: Every 11 years, the number of spots dotting the surface of the Sun increases and decreases like clockwork. Astronomers have been tracking the 11-year sunspot cycle for more than 400 years, using it to better understand the chaotic magnetic field the Sun puts out. (The current solar cycle, number 25, started in 2019.) The timing of the solar cycle is remarkably consistent: Sunspot numbers rise and fall, rise and fall…except for that time that they disappeared and weren’t seen again for 70 years. That period of time, from 1645 to 1715, is known as the Maunder Minimum, named after 19th century British astronomers Edward and Annie Maunder. Astronomers still don’t understand why the Sun ceased making sunspots for 70 years, but a new analysis of more than 5 decades of measurements of nearby stars has identified one that might be undergoing its own Maunder-like minimum. The star, HD 166620, could help scientists understand this mysteriously quiescent period of the Sun’s history and unlock clues about how the solar dynamo functions.…

2022-02-09. Solar Storm Destroys 40 New SpaceX Satellites in Orbit. By Robin George Andrews, The New York Times. Excerpt: Over the past three years, SpaceX has deployed thousands of satellites into low-Earth orbit as part of its business to beam high-speed internet service from space. But the company’s latest deployment of 49 new satellites after a Feb. 3 launch did not go as planned. As a consequence of a geomagnetic storm triggered by a recent outburst of the sun, up to 40 of 49 newly launched Starlink satellites have been knocked out of commission. They are in the process of re-entering Earth’s atmosphere, where they will be incinerated. …The sun has an 11-year-long cycle in which it oscillates between hyperactive and quiescent states. Presently, it is ramping up to its peak, which has been forecast to arrive around 2025. This recent solar paroxysm was relatively moderate by the sun’s standards. “I have every confidence that we’re going to see an extreme event in the next cycle, because that typically is what happens during a solar maximum,” said Hugh Lewis, a space debris expert at the University of Southampton in England. If a milquetoast outburst can knock out 40 Starlink satellites hanging out at low orbital altitudes, a more potent solar scream has the potential to inflict greater harm on the mega-constellations of SpaceX and other companies.… []

2021-12-15. NASA probe that ‘touched the sun’ for first time could help people better understand the solar system. By Timothy Bella, The Washington Post. Excerpt: A NASA spacecraft became the first to “touch the sun,” scientists announced Tuesday — a long-awaited milestone and a potential giant leap in understanding the sun’s influence on the solar system. The Parker Solar Probe successfully flew through the sun’s corona, or upper atmosphere, in April to sample particles and its magnetic fields, according to research published in the journal Physical Review Letters. The findings were also announced Tuesday at the American Geophysical Union Fall Meeting in New Orleans. …The spacecraft, launched three years ago in an effort to study the sun and its dangers, will help scientists uncover significant and unknown information about Earth’s closest star, including how the flow of the sun’s particles can influence the planet. …The spacecraft’s brush with the sun is the culmination of a mission more than 60 years in the making. …After the nation’s top scientists in 1958 compiled a list of missions that they thought NASA, then a brand-new space agency, should pursue, dreams such as the Hubble Space Telescope, the twin Voyager spacecraft and the Apollo programall eventually became realities. But the goal of reaching the sun remained elusive.… [] See also NASA blog entry for 11/24/2021: Parker Solar Probe Completes a Record-Setting Swing by the Sun.

2020-07-16. Solar Orbiter’s First Images Reveal “Campfires” on the Sun. By European Space Agency (ESA). Excerpt: The first images from Solar Orbiter, a new Sun-observing mission by ESA and NASA, have revealed omnipresent miniature solar flares, dubbed ‘campfires’, near the surface of our closest star. …Solar Orbiter, launched on 10 February 2020, carries six remote-sensing instruments… and four in situ instruments that monitor the environment around the spacecraft. By comparing the data from both sets of instruments, scientists will get insights into the generation of the solar wind, the stream of charged particles from the Sun that influences the entire Solar System. …The campfires shown in the first image set were captured by the Extreme Ultraviolet Imager (EUI) from Solar Orbiter’s first perihelion, the point in its elliptical orbit closest to the Sun. At that time, the spacecraft was only 77 million km away from the Sun, about half the distance between Earth and the star. “The campfires are little relatives of the solar flares that we can observe from Earth, million or billion times smaller,” says David Berghmans of the Royal Observatory of Belgium (ROB), Principal Investigator of the EUI instrument…. “The Sun might look quiet at the first glance, but when we look in detail, we can see those miniature flares everywhere we look.”… []  See also July 16 New York Times article: Closest Pictures Ever Taken of Sun Show Tiny Campfire Flares []

2020-06-24. A Decade of Sun. By NASA Solar Dynamics Observatory (SDO). Excerpt: YouTube video – As of June 2020, NASA’s Solar Dynamics Observatory — SDO — has now been watching the Sun non-stop for over a full decade. From its orbit in space around the Earth, SDO has gathered 425 million high-resolution images of the Sun, amassing 20 million gigabytes of data over the past 10 years. This information has enabled countless new discoveries about the workings of our closest star and how it influences the solar system. …While SDO has kept an unblinking eye pointed towards the Sun, there have been a few moments it missed. The dark frames in the video are caused by Earth or the Moon eclipsing SDO as they pass between the spacecraft and the Sun. A longer blackout in 2016 was caused by a temporary issue with the AIA instrument that was successfully resolved after a week. The images where the Sun is off-center were observed when SDO was calibrating its instruments…. []  

2020-04-30. There’s Something Special About the Sun: It’s a Bit Boring. By Adam Mann, The New York Times. Excerpt: The sun, like all stars, is a blazing ball of fusion-powered plasma. From its surface emerge magnetic field lines that can cause dark patches known as sunspots. Turn up the activity of these magnetic whorls, and you get more solar storms flinging deadly charged particles and radiation throughout our solar system. If enough of these punishing waves hit a rocky planet, that planet might end up microwaved into a dreary condition where nothing could live. …A study released Thursday in the journal Science suggests that our sun is rather tame compared with its stellar siblings, and that hundreds of other sun-like stars in our galaxy have on average five times more magnetic activity than our parent star. …Some previous studies also implied that the sun was quieter than other similar stars. But competing evidence has also found the sun’s activity level is normal for stars of its size. …Timo Reinhold, an astrophysicist at the Max Planck Institute for Solar System Research in Göttingen, Germany, and co-author of the paper …and colleagues looked at data collected by NASA’s retired Kepler space telescope, which continuously monitored approximately 150,000 stars in the Milky Way for four years to find exoplanets, and was capable of observing brightness variations from activity such as the appearance and disappearance of starspots. …During times of peak magnetic activity, when spots pop out all over the surface, a star will dim. Our sun’s cycle lasts about 11 Earth years. For the sun, this dimming is negligible. Data from the past 140 years indicates that its brightness changes by less than a tenth of a percent over the course of its cycle. But for the stars studied by Kepler, the variability could be up to 12 times that amount…. [

2020-01-29. World’s largest solar telescope takes its first shot. 
By Daniel Clery, Science Magazine. Excerpt: This new close-up of the turbulent boiling plasma of the solar surface is the debut image of the largest telescope ever built for staring at the Sun. Sporting a 4-meter-wide mirror—twice the size of any existing solar scope—and a vantage point 3000 meters up on the summit of Haleakala on the Hawaiian island of Maui—the Daniel K. Inouye Solar Telescope (DKIST) will reveal unprecedented detail of processes that channel energy from the Sun’s interior into its atmosphere, the corona. Researchers hope that by zooming in on cell-like structures like those shown above—each about the size of Texas—they can learn what causes the Sun to launch powerful flares out into space, potentially causing damage to Earth’s satellites, power grids, and communications. Such information could help scientists give warnings of such events days rather than minutes ahead. DKIST researchers also hope to finally resolve nagging solar mysteries such as: Why is the corona—at more than 1 million degrees C—so much hotter than the Sun’s surface, and what launches the solar wind out into space? …. [] 

2019-12-04. Parker probe traces solar wind to its source on sun’s surface. By Robert Sanders, UC Berkeley News. [] For GSS A Changing Cosmos chapter 3. Excerpt: A year ago, NASA’s Parker Solar Probe flew closer to the sun than any satellite in history, collecting a spectacular trove of data from the very edge of the sun’s million-degree corona. …that data has allowed solar physicists to map the source of a major component of the solar wind that continually peppers Earth’s atmosphere, while revealing strange magnetic field reversals that could be accelerating these particles toward our planet. These accelerated particles interact with Earth’s magnetic field, generating the colorful northern and southern lights. But they also have the potential to damage the electrical grid and telecommunications networks on Earth’s surface, threaten orbiting satellites and perhaps endanger astronauts in space. …“There was a major space weather event in 1859 that blew out telegraph networks on Earth and one in 1972 that set off naval mines in North Vietnam, just from the electrical currents generated by the solar storm,” said Stuart Bale, a University of California, Berkeley, professor of physics and lead author of an article about new results from the probe’s FIELDS experiment. …One of the main goals of the Parker Solar Probe is to discover the source of the “slow” solar wind and how it is accelerated in the hot atmosphere of the sun — the 1 million-degree Celsius (about 2 million degrees Fahrenheit) solar corona. …“The first three encounters of the solar probe that we have had so far have been spectacular,” said Bale, the principle investigator for FIELDS. “We can see the magnetic structure of the corona, which tells us that the solar wind is emerging from small coronal holes; we see impulsive activity, large jets or switchbacks which we think are related to the origin of the solar wind; we see instability — the gas itself is unstable and is generating waves on its own. And we are also surprised by the ferocity of the dust environment in the inner heliosphere.” …Another surprise was the dust that peppered the spacecraft repeatedly during each fly-by at perihelion — the point in the orbit where the spacecraft was closest to the sun. …the dust particles are likely debris from asteroids or comets that melted near the sun and left behind their trapped dust….  

2017-07-31. The Eclipse That Revealed the Universe. By Dennis Overbye, The New York Times. Excerpt: In 1919, British astronomers photographed a solar eclipse and proved that light bends around our sun — affirming Einstein’s theory of general relativity. …Few eclipses have had more impact on modern history than the one that occurred on May 29, 1919, more than six minutes of darkness sweeping across South America and across the Atlantic to Africa. It was during that eclipse that the British astronomer Arthur Eddington ascertained that the light rays from distant stars had been wrenched off their paths by the gravitational field of the sun. That affirmed the prediction of Einstein’s theory of general relativity, ascribing gravity to a warp in the geometry of space-time, that gravity could bend light beams….

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.”….

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….

2016-12-01. Four New Names Officially Added to the Periodic Table of Elements. By Nicholas St. Fleur, The New York Times. [We’ll need to get new Periodic Tables!] Excerpt: It’s official. Chemistry’s highest gatekeepers have accepted the newly proposed names for elements 113, 115, 117 and 118. Please welcome to the periodic table: Nihonium, Moscovium, Tennessine and Oganesson. Scientists first synthesized the new elements between 2002 and 2010, but it wasn’t until December of 2015 that the International Union of Pure and Applied Chemistry officially recognized the discoveries. Then in June of this year the scientists who discovered the super-heavy, highly-reactive elements sent Iupac their suggested names. After a five-month waiting period when members of the public could ask questions about the new elements, the foursome were approved on Wednesday, formally filling their boxes in chemistry’s most fundamental table….

2015-10-07. Physics Nobel Winners Also Solved Solar Mystery. By JoAnna Wendel, Earth & Space Science News. Excerpt: Although they won the prize for showing neutrinos have mass, the two Nobel-winning physicists also solved a long-standing mystery of solar neutrinos. Physicists Takaaki Kajita from the University of Tokyo in Japan and Arthur B. McDonald of Queen’s University in Kingston, Ontario, Canada, received the Nobel Prize in Physics yesterday for their pioneering discovery that neutrinos, elusive subatomic particles that are constantly streaming through all of space, even straight through the Earth, can change from one form to another. This finding in turn proved that the tiny particles have mass—a discovery that challenges the prevailing theory of particle physics, known as the standard model. In the process of discovering the neutrino’s changeable nature, the scientists also solved a decades-long mystery about the Sun: the case of the “missing” neutrinos….In the 1960s, scientists were investigating the theory that the Sun’s energy comes from nuclear fusion of hydrogen into helium deep within its core—a reaction that releases neutrinos, which zip through the Sun toward Earth. Because the reaction happens so frequently, scientists expected to find a vast number of neutrinos hitting the Earth. However, their models disagreed with experimental evidence—they found only a third of the neutrinos they expected. So where were the missing neutrinos? …It turns out that the neutrinos were there, but some had morphed. In the experiments that helped secure their Nobel Prize, both McDonald and Kajita helped make this discovery….

2015-06-17. Traces of Earliest Stars That Enriched Cosmos Are Spied. By Dennis Overbye, New York Times. Excerpt: Astronomers said Wednesday that they had discovered a lost generation of monster stars that ushered light into the universe after the Big Bang and jump-started the creation of the elements needed for planets and life before disappearing forever. …in the aftermath of the Big Bang only hydrogen, helium and small traces of lithium were available to make the first stars. Such stars could have been hundreds or thousands of times as massive as the sun, according to calculations, burning brightly and dying quickly, only 200 million years after the universe began. Their explosions would have spewed into space the elements that started the chain of thermonuclear reactions by which subsequent generations of stars have gradually enriched the cosmos with elements like oxygen, carbon and iron. …in a paper to be published in The Astrophysical Journal, an international crew of astronomers led by David Sobral of the University of Lisbon, in Portugal, and the Leiden Observatory, in the Netherlands, said they had spotted the signature of these first-generation stars in a recently discovered galaxy that existed when the universe was only about 800 million years old. …The galaxy, known as CR7, is three times as luminous as any previously found from that time, the authors said. Within it is a bright blue cloud that seems to contain only hydrogen and helium….

2015-05-03. Halley’s Eclipse: a coup for Newtonian prediction and the selling of science. By Rebekah Higgit, The Guardian. Excerpt: 300 years ago, on the 3rd of May 1715, a rare solar eclipse occurred over England. It was an opportunity too good to miss for those promoting new astronomical theories – and their own careers. In 1715, 300 years ago today, a total solar eclipse was visible across a broad band of England. It was the first to be predicted on the basis of the Newtonian theory of universal gravitation, its path mapped clearly and advertised widely in advance. Visible in locations such as London and Cambridge, both astronomical experts and the public were able to see the phenomena and be impressed by the predictive power of the new astronomy. Wikipedia will tell you that this is known as Halley’s Eclipse, after Edmond Halley, who produced accurate predictions of its timing and an easily-read map of the eclipse’s path. Halley did not live to see the confirmation of his predictions of a returning comet – a 1759 triumph for the Newtonian system – but he was able to enjoy his 1715 calculations, which were within 4 minutes, and to improve on them with a corrected map (above). He observed the eclipse from the Royal Society’s building in Crane Court on a morning with a sky of “perfect serene azure blew”….

2014-09-01. Research Aimed at the Heart of the Sun.  Excerpt: With the aid of a powerful instrument, researchers have detected subatomic particles produced by fusion reactions at the very core of the sun. The particles are neutrinos, and the ones detected in this study are low in energy but abundant in number, said Andrea P. Pocar, a physicist at the University of Massachusetts, Amherst. The neutrinos are formed by a fusion reaction between two protons at the core of the sun; they travel to Earth in just eight minutes…. “Previous experiments had measured neutrinos from the sun, but those neutrinos are present in very low numbers,” Dr. Pocar said. “These make up about 90 percent of the total neutrinos from the sun.” Dr. Pocar and his colleagues, a group of more than 90 physicists from around the world, published their findings in the current issue of the journal Nature. They relied on the Borexino detector, an instrument located deep beneath Italy’s Apennine Mountains that is sensitive enough to detect the low-energy particles…. By Sindya N. Bhanoo, The New York Times.

19 August 2011. Stanford scientists find way to predict sunspots. By David Perlman, San Francisco Chronicle. Excerpt: Stanford physicists probing the sun’s deep interior have predicted the emergence of sunspots on the surface a full two days before they appear, providing the first early warning of the violent solar storms that can endanger astronauts in space, disrupt electric power grids on Earth, and plunge cities into darkness…
Solar physicist David Hathaway at NASA’s Marshall Space Center in Huntsville, Ala., called the Stanford group’s predictions “an important result.”
“It’s long been our hope to see the storms of sunspots before they show up,” Hathaway said. The experiments that led to today’s report in the Journal Science were conducted by Stathis Ilonidis, a graduate student in physics at Stanford, and his colleagues…

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?

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. See 

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.”