Solar Astronomy Archives

October 26, 2009December 24, 2015 by Nancy Atkinson

MESSENGER Solves Solar Flare Mystery

Antenna Array — MESSENGER on the sunside of Mercury. Credit: NASA

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In a case of being in the right place at the right time, the MESSENGER spacecraft was able to capture a average-sized solar flare, allowing astronomers to study high-energy solar neutrons at less than 1 astronomical unit (AU) from the sun for the first time. When the flare erupted on Dec. 31, 2007, MESSENGER – on course for entering orbit around Mercury — was flying at about half an AU, said William C. Feldman, a scientist at the Planetary Science Institute. Previously, only the neutron bursts from the most powerful solar flares have been recorded on neutron spectrometers on Earth or in near-Earth orbit. The MESSENGER results help solve a mystery of why some coronal mass ejections produce almost no energetic protons that reach the Earth, while others produce huge amounts.

Solar flares spew high-energy neutrons into interplanetary space. Typically, these bursts last about 50 to 60 seconds at the sun. But MESSENGER’s Neutron Spectrometer was able to record neutrons from this flare over a period of six to ten hours. “What that’s telling us is that at least some moderate-sized flares continuously produce high-energy neutrons in the solar corona.” Said Feldman. “From this fact, we inferred the continuous production of protons in the 30-to-100-MeV (million electron volt) range due to the flare.”
About 90 percent of all ions produced by a solar flare remain locked to the sun on closed magnetic lines, but another population results from the decay of the neutrons near the sun. This second population of decayed neutrons forms an extended seed population in interplanetary space that can be further accelerated by the massive shock waves produced by the flares, Feldman said.

“So the important results are that perhaps after many flare events two things may occur: continuous production of neutrons over an extended period of time and creation of seed populations of neutrons near the sun that have decayed into protons,” Feldman said. “When coronal mass ejections (nuclear explosions in the corona) send shock waves into space, these feedstock protons are accelerated into interplanetary space.”

“There has always been the question of why some coronal mass ejections produce almost no energetic protons that reach the Earth, while others produce huge amounts,” he added. “It appears that these seed populations of energetic protons near the sun could provide the answer, because it’s easier to accelerate a proton that already has an energy of 1 MeV than a proton that is at 1 keV (the solar wind).”

The seed populations are not evenly distributed, Feldman said. Sometimes they’re in the right place for the shock waves to send them toward Earth, while at other times they’re in locations where the protons are accelerated in directions that don’t take them near Earth.

The radiation produced by solar flares is of more than academic interest to NASA, Feldman added. Energetic protons from solar flares can damage Earth-orbiting satellites and endanger astronauts on the International Space Station or on missions to the Moon and Mars.

“People in the manned spaceflight program are very interested in being able to predict when a coronal mass ejection is going to be effective in generating dangerous levels of high-energy protons that produce a radiation hazard for astronauts,” he said.

To do this, scientists need to know a lot more about the mechanisms that produce flares and which flare events are likely to be dangerous. At some point they hope to be able to predict space weather — where precipitation is in the form of radiation — with the same accuracy that forecasters predict rain or snow on Earth.

MESSENGER could provide significant data toward this goal, Feldman observed. “What we saw and published is what we hope will be the first of many flares we’ll be able to follow through 2012,” he said. “The beauty of MESSENGER is that it’s going to be active from the minimum to the maximum solar activity during Solar Cycle 24, allowing us to observe the rise of a solar cycle much closer to the sun than ever before.”

MESSENGER is currently orbiting the sun between 0.3 and 0.6 AU — (an AU is the average distance between the Earth and the sun, or about 150,000 km) — on its way to orbit insertion around Mercury in March 2011. At Mercury, it will be within 0.45 AU of the sun for one Earth year.

Read the team’s paper: Evidence for Extended Acceleration of Solar Flare Ions from 1-8-MeV Solar Neutrons Detected with the MESSENGER Neutron Spectrometer.

Source: PSI

October 15, 2009December 24, 2015 by Nancy Atkinson

Spacecraft Detects Mysterious “Ribbon” at Edge of Solar System

Accurate timing of the incoming ENAs allows the IBEX team to obtain a higher resolution in the latitudinal direction. The inset at right shows some of the fine detail of the ribbon. Credit: Southwest Research Institute (SwRI)

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Since it launched a year ago, the Interstellar Boundary Explorer (IBEX) has been monitoring heliosphere and how our Sun interacts with and the local interstellar medium — the gas and dust trapped in the vacuum of space. The first results from the mission, combined with data from the Cassini mission, are showing the heliosphere to be different from what researchers have previously thought. Data show an unexpected bright band or ribbon of surprisingly high-energy emissions. “We knew there would be energetic neutral atoms coming in from the very edge of the heliosphere, and our theories said there would be small variations in their emissions,” said David McComas, IBEX Principal Investigator at a press conference on Thursday. “But instead we are seeing two-to-three hundred percent variations, and this is not entirely understood. Whatever we thought about this before is definitely not right.”

The energies IBEX has observed range from 0.2 to 6.0 kiloelectron volts, and the scientists said its flux is two to three times greater than the ENA activity throughout the rest of the heliosphere. McComas and his colleagues said that no existing model can explain all the dominant features of this “ribbon.” Instead, they suggest that these new findings will prompt a change in our understanding of the heliosphere and the processes that shape it.

This image illustrates one possible explanation for the bright ribbon of emission seen in the IBEX map. The galactic magnetic field shapes the heliosphere as it drapes over it. The ribbon appears to trace the area where the magnetic field is most parallel to the surface of the heliosphere (the heliopause). Credit: Southwest Research institute

McComas suggested that the energetic neutral atom (ENA) ribbon could be caused by interactions between the heliosphere and the local interstellar magnetic field. “The local interstellar magnetic field is oriented in such a way that it correlates with the ribbon. If you ‘paint’ the ribbon on the boundary of the heliosphere, the magnetic field is like big bungie cords that pushing in along the sides and at southern part of the heliosphere. Somehow the magnetic field seems to be playing a dominant roll in these interactions, but we don’t know it could produced these higher fluxes. We have to figure out what physics were are missing.”

The solar wind streaks away from the sun in all directions at over a millions kilometers per hour. It creates a bubble in space around our solar system.

For the first ten billion kilometers of its radius, the solar wind travels at over a million kilometers per hour. It slows as it begins to collide with the interstellar medium, and the point where the solar wind slows down is the termination shock; the point where the interstellar medium and solar wind pressures balance is called the heliopause; the point where the interstellar medium, traveling in the opposite direction, slows down as it collides with the heliosphere is the bow shock.

The Voyager spacecraft have explored this region, but didn’t detect the ribbon. Team member Eric Christian said the ribbon wound in between the location of Voyager 1 and 2, and they couldn’t detect it in their immediate areas. Voyager 1 spacecraft encountered the helioshock in 2004 when it reached the region where the charged particles streaming off the sun hit the neutral gas from interstellar space. Voyager 2 followed into the solar system’s edge in 2007. While these spacecraft made the first explorations of this region, IBEX is now revealing a a more complete picture, filling in where the Voyagers couldn’t. Christian compared Voyager 1 and 2 to be like weather stations while IBEX is first weather satellite to provide more complete coverage.

McComas said his first reaction when the data started coming in was that of terror because he thought something must be wrong with the spacecraft. But as more data kept coming back each week, the team realized that they were wrong, and the spacecraft was right.

“Our next steps will be to go through all the detailed observations and rack them up against the various models and go find what it is that we are missing, what we’ve been leaving out,” he said.

For more information and visuals, see this NASA webpage.

September 23, 2009December 24, 2015 by Nancy Atkinson

Two Equinox Sunspots

Sunspots 1026 and1027 are members of new Solar Cycle 24. Photo credit: SOHO/MDI

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Two sunspots appeared on old Sol yesterday just as Earth’s orbit ushered in the Autumnal Equinox. Two sunspots showing up at once hasn’t happened in more than a year, and over 80% of the days in 2009 have been “sunspotless” during this deepest solar minimum in a century. Spaceweather.com had a great picture, below, of the first sunspot that appeared, #1026, taken by astrophotographer Peter Lawrence. Lawrence said there was a lot going on around the new sunspot. “The spot’s dark core is surrounded by active fibrils and a swirling magnetic filament that gives the region a nice 3D appearance.”

Check out Spaceweather.com for more (and new images) of the new sunspots.

September 13, 2009December 24, 2015 by Nancy Atkinson

Temporary Radiation Belt Discovered at Saturn

Radiation belt map of the ions with energies between 25-60 MeV, in Saturn's magnetosphere, based on several years of Cassini MIMI/LEMMS data. The structure of this radiation belt is almost perfectly stable for more than 5 years of Cassini observations, despite the intense variability of the radiation belts, outside the location of Tethys.

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A new, temporary radiation belt has been detected at Saturn, located about 377,000 km from the center of the planet, near the orbit of the moon Dione. The temporary radiation belt was short-lived and formed three times in 2005. It was observed as sudden increases in the intensity of high energy charged particles in the inner part of Saturn’s magnetosphere, in the vicinity of the moons Dione and Tethys, and likely was caused by a change in the intensities of cosmic rays at Saturn.

“These intensifications, which could create temporary satellite atmospheres around these moons,” said Dr. Elias Roussos, “occurred three times in 2005 as a response to an equal number of solar storms that hit Saturn’s magnetosphere and formed a new, temporary component to Saturn’s radiation belts.”

The discovery was made possible by Cassini’s five-plus year mission, allowing scientists to observe and assess changes in Saturn’s radiation belts. An international team of astronomers made the discovery analyzing data from the Magnetospheric Imaging instrument (MIMI) on Cassini MIMI’s LEMMS sensor, which measures the energy and angular distribution of charged particles in the magnetic bubble that surrounds Saturn.

The new belt, which has been named “the Dione belt”, was only detected by MIMI/LEMMS for a few weeks after each of its three appearances. The team believe that newly formed charged particles in the Dione belt were gradually absorbed by Dione itself and another nearby moon, named Tethys, which lies slightly closer to Saturn at an orbit of 295 000km.

Unlike the Van Allen belts around the Earth, Saturn’s radiation belts inside the orbit of Tethys are very stable, showing negligible response to solar storm occurrences and no variability over the five years that they have been monitored by Cassini.

Interestingly, it was found that the transient Dione belt was only detected outside the orbit of Tethys. It appeared to be clearly separated from the inner belts by a permanent radiation gap all along the orbit of Tethys.

“Our observations suggest that Tethys acts as a barrier against inward transport of energetic particles and is shielding the planet’s inner radiation belts from solar wind influences. That makes the inner, ionic radiation belts of Saturn the most isolated magnetospheric structure in our solar system“, said Dr Roussos.

The radiation belts within Tethys’s orbit probably arise from the interaction of the planet’s main rings and atmosphere and galactic cosmic ray particles that, unlike the solar wind, have the very high energies needed to penetrate the innermost Saturnian magnetosphere. This means that the inner radiation belts will only vary if the cosmic ray intensities at the distance of Saturn change significantly.

However, Roussos emphasized that outside the orbit of Tethys, the variability of Saturn’s radiation belt might be enhanced in the coming years as solar maximum approaches. “If solar storms occur frequently in the new solar cycle, the Dione belt might become a permanent, although highly variable, component of Saturn’s magnetosphere, which could affect significantly Saturn’s global magnetospheric dynamics,” he said.

The new findings were presented at the European Planetary Science Congress in Potsdam, Germany.

July 22, 2009December 24, 2015 by Tammy Plotner

July 22, 2009 Total Solar Eclipse from China – Let’s Chase!

Eclipse from Chongqing Municipality (Xinhua/Liu Chan)

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The total solar eclipse which just occurred on the 22nd of July 2009 was the longest maximum duration of the 21st century. Not since Saros 1991 have astronomers and eclipse chasers been treat to such an event! Totality lasted over six and a half minutes at maximum. duration. The event started in India along the western shore near Surat moved towards Butan and reached the southern tip of Nepal and the northern edge of Bangladesh.

For other lucky astronomers like Vietnamese student Dang Anh Tuan at Hanoi National University of Education, the eclipse path also took the event over cities like Chengdu, Suining, Chonging, Wuhan, Xiaogan, Hangzhou, and Shanghai – and event which yielded five minutes of totality. Leaving Shanghai the shadow path raced across the ocean, to fall across islands such as Toshima and Akusaki south of Japan and eventually the Marshall islands. Where was the longest point? The maximum eclipse duration of 6 minutes and 43 seconds occurs far off the coast in the Pacific Ocean! Are you ready to become an eclipse chaser? Then follow me…

I’ve always wanted to go on an eclipse chasing journey, but I’m afraid I’ll never quite be rich or well enough, unless it happens somewhere near me. But, my world is one that is both large and very small at the same time… And filled with wonderful friends from every corner. Bill Fish of Lubrizol Advanced Materials made my day by sending me some photos shared by their employees immediately after the eclipse had ended.

Seeing such incredible beauty, like this image of Bailey’s Beads taken in Chong Qing, and in just a few hours meeting great people like Jessica Bian, Kelly Zhou, Jun-Sheng Cao, Leo Chi, Mars Meng, Lucy Wang and Helen Tong felt so wonderful. Truly astronomy is a language we all speak! By roughly 9:00 in the morning, this is what they would have seen from their office windows or rooftops. Can you imagine what an exciting day it must have been?!

Well, needless to say, once I saw something like that, all my worries and cares for the day seemed so small. Even though I couldn’t leave my desk, the marvelous opportunity for me to become an eclipse chaser had just opened up like a fortune cookie right before my eyes. It was time for me to learn Chinese… and check out this awesome video done by Hubei Jingmen!

But he wasn’t alone… And neither was I. Millions of folks all over China were witnessing the eclipse and with each video I felt more and more like I was there, too.

“In the Zhejiang Haining, huge amounts of people were out to observe the wonderful total solar eclipse. The observation person is sea of people. But two big marvelous sight’s secret directions are the Sun, the Earth and the Moon…. “three meet”.”

Now, let’s travel to Beijing where the sky was enveloped in mist. Despite the weather, some 200 astronomy watchers queued in front of the Beijing Astronomical Observatory at 6:30 a.m. Staff at the observatory said the eclipse had sparked interest in astronomy. Yang Jing, a high-school student from Urumqi said. “I didn’t expect such a big crowd to watch the eclipse!”

Our next video comes from Chengdu… You can imagine the city stopping for just a moment to look skyward. “As soon as the totality happened, the clouds closed in so we couldn’t see the corona. That’s a pity,” said Zhen Jun, a man whose work unit had given the day off for the spectacle.

Now we move on to Hangzhou… When thousands of people thronged outdoors for the longest total solar eclipse of the 21st century, animals at the zoo in east China’s Hangzhou City also reacted, quickly and confusedly. The shadow of the moon disoriented birds whose body clock and direction depend on the sun. Red-crowned cranes and flamingos that had been wandering or drinking water suddenly fell asleep during the brief blackout of eclipse. But when the sun rays came out again several minutes later, the birds emerged from their cages and started the life of another “day.”

Even though I don’t understand a word of Chinese, I understand every word of “human”. Listen to them… Listen to the people talk and the children! How I wish I were there, too! Said Kang Hui:“The celestial phenomenon was a marvelous sight”. Are you ready to move again and follow the shadow? Then, let’s take a trip to Shanxi Linfen…

Now, I’ll race you to Hong Kong! Hundreds of people thronged into the Hong Kong Space Museum Wednesday morning for the Partial Solar Eclipse Observation activity. The public watched the eclipse using telescopes equipped with a safe filtering system and projection under guidance provided by the Space Museum.

Gosh, some of that footage feels like you could just reach right out and wrap your hand around that Moon, doesn’t it? Now let’s head to the middle of Anhui Yi County…

This one where you can see the corona dazzling is simply extraordinary. Can you imagine what it would feel like to be able to see this in real life? Come on… Let’s continue our eclipse chasing trip to Shanghai! It was raining in Shanghai when the total eclipse occurred at 9:35 a.m. The city put extra police on streets, and more than 30 police vessels patrolled the coast. Only street lamps were left on, as the city turned off all landscape lighting to allow people to watch the solar eclipse.

In Shanghai, more than 4,000 people ended up in suburban Yuehu Park of Sheshan Observatory and Yangshan Deep Water Port, two prime spots in the city, to observe the eclipse. Shanghai Science Hall also organized a public viewing session in downtown Fuxing Park and seventeen observation stations were set up in the solar eclipse path from Yunnan province to Zhejiang province.

Now we travel to the Henan Luoyang and say hello to these great kids and their equally excited parents and grandparents as we catch a partial eclipse.

“Luoyang’s light rain was intermittent, in the morning about 10:45, the Sun opened out the cloud layer to reveal the face of what was to come. The residents might see the partial solar eclipse! This kind of picture has not been seen here for a very long time. The Henan Luoyang partial solar eclipse looks just like the raging fire phoenix raising slowly.”

Shall we continue to Taiwan? Then grab us a cup of coffee and I will meet you at the Taibei Municipal Astronomy Scientific Culture Hall.

Shall we travel to Shenyang? This was also a partial solar eclipse location, but witnesses said the Moon “seemed like it was curved”.

Now, come with us to Ningbo. This one is so beautiful I wept when I saw it…

“This morning we just watched the total solar eclipse, which happens every 500 years. When the whole sun is blacken by the Moon. Everyone is highly excited. It’s pity I forgot to bring the camera by my side and the moment is passed away soon. But I am still lucky to see the sight. 500 years……how significant!”

When I was a child, I was charmed by a story about Ping the Duck, who lived on the Yangtze River. The last of the hundreds of videos I have watched today that I’d like to share with you is part of the Yangtze River collection.

Enjoy this beautiful composite image taken by Yang Lei at a park in southwest China’s Chongqing Municipality. It has been my most wonderful pleasure over the day to spend time in the East…

Chasing the Sun!

Solar eclipse occurring over Taipei of southeast China's Taiwan

My many thanks to Bill Fish for getting me started, Jessica Bian for investigating and translating and the wonderful people at Sina for sharing!

July 22, 2009December 24, 2015 by Tammy Plotner

July 22, 2009 Total Solar Eclipse – Incoming News…

July 22, 2009 Solar Eclipse Image Submitted By Bill Fish

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The total solar eclipse which just occured on the 22nd of July 2009 was the longest in terms of maximum totality duration of the 21st century – lasting over six and a half minutes. Not since Saros 1991 have astronomers and eclipse chasers been treated to such a length of time! The eclipse footprint started in India along the western shore near Surat moved towards Butan and reached the southern tip of Nepal and the northern edge of Bangladesh. For other lucky astronomers, the eclipse path also took the event over the Chinese cities of Chengdu, Suining, Chonging, Wuhan, Xiaogan, Hangzhou, and Shanghai – yielding five minutes of totality. Leaving Shanghai the shadow raced across the ocean to fall across islands such as Toshima and Akusaki south of Japan and eventually the Marshall islands. Where did the longest time occur? The maximum eclipse duration of 6 minutes and 43 seconds was far off the coast in the Pacific Ocean! As I write this announcement, our readers are sending in their photos and stories to my home email (send them!!) and I just couldn’t wait to show you some of the beginning results. It will take a short time to do a little translation work… But it’s a small, wonderful world and this article will be updated very soon!

June 19, 2009December 24, 2015 by Anne Minard

New, Close-Up View Probes the Nature of Sunspots

©UCAR, image courtesy Matthias Rempel, NCAR

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Seriously, I don’t think we should stare at this too long … but for scientists who plan to, this new, high-resolution view of a sunspot stands to unlock secrets of the Sun’s mysterious energetics.

In the just-released image above, the interface between a sunspot’s umbra (dark center) and penumbra (lighter outer region) shows a complex structure with narrow, almost horizontal (lighter to white) filaments embedded in a background having a more vertical (darker to black) magnetic field. Farther out, extended patches of horizontal field dominate. For the first time, scientists have modeled this complex structure in a comprehensive 3D computer simulation, giving scientists their first glimpse below the visible surface.

The international team of scientists, led by the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, say the high-resolution simulations of sunspot pairs open the way for researchers to learn more about the vast, mysterious dark patches on the Sun’s surface. Sunspots are the most striking surface manifestations of solar magnetism, and they are associated with massive ejections of charged plasma that can cause geomagnetic storms and disrupt communications and navigational systems. They also contribute to variations in overall solar output, which can affect weather on Earth and exert a subtle (and as-yet deciphered) influence on climate patterns.

The new research, by scientists at NCAR and the Max Planck Institute for Solar System Research (MPS) in Germany, appears this week in Science Express.

“This is the first time we have a model of an entire sunspot,” says lead author Matthias Rempel, a scientist at NCAR’s High Altitude Observatory. “If you want to understand all the drivers of Earth’s atmospheric system, you have to understand how sunspots emerge and evolve. Our simulations will advance research into the inner workings of the Sun as well as connections between solar output and Earth’s atmosphere.”

Ever since outward flows from the center of sunspots were discovered 100 years ago, scientists have worked toward explaining the complex structure of sunspots, whose number peaks and wanes during the 11-year solar cycle. Sunspots encompass intense magnetic activity that is associated with solar flares and massive ejections of plasma that can buffet Earth’s atmosphere. The resulting damage to power grids, satellites, and other sensitive technological systems takes an economic toll on a rising number of industries.

Creating such detailed simulations would not have been possible even as recently as a few years ago, before the latest generation of supercomputers and a growing array of instruments to observe the Sun. Partly because of such new technology, scientists have already made advances in solving the equations that describe the physics of solar processes.

Source: University Corporation for Atmospheric Research (UCAR), via American Astronomical Society (AAS) press wire

June 17, 2009April 26, 2016 by Anne Minard

The Case of the Missing Sunspots: Solved?

NASA image of a sunspot up close. Solar physicists are working to understand why the Sun has seen so few in the past year.

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The Sun has seen precious few sunspots (as shown in this NASA closeup) in the past year, and solar physicists have been working to understand why. Now, some think they have an answer.

According to work being presented this week at the meeting of the Solar Physics Division of the American Astronomical Society, a solar jet stream deep inside the Sun is migrating slower than usual through the star’s interior and it’s at least associated with — if not causing — the current lull in sunspots and solar activity.

The Sun normally undergoes an eleven-year cycle of magnetic activity related to sunspots, solar flares, and the interplanetary storms called “CMEs.” The current “solar minimum” quiet period has been unusually long and deep, confounding scientists who hope to understand the origins of space weather and the Sun’s magnetic field.

Rachel Howe and Frank Hill, both scientists with the National Solar Observatory (NSO) in Tucson, Arizona, used long-term observations from the NSO’s Global Oscillation Network Group facility to detect and track an east-to-west jet stream, known as the “torsional oscillation,” at depths of ~1,000 to 7,000 km (about 600 to 4,000 miles) below the surface of the Sun. The Sun generates new jet streams near its poles every 11 years; the streams migrate slowly, over a period of 17 years, to the equator and are associated with the production of sunspots once they reach a critical latitude of 22 degrees.

Howe and Hill found that the stream associated with the new solar cycle has moved sluggishly, taking three years to cover a 10-degree range in latitude compared to two years for the last solar cycle, but has now reached the critical latitude. The current solar minimum has become so long and deep, some scientists have speculated the Sun might enter a long period with no sunspot activity at all. The new result both shows that the Sun’s internal magnetic dynamo continues to operate, and heralds the beginning of a new cycle of solar activity.

“It is exciting to see,” said Hill, “that just as this sluggish stream reaches the usual active latitude of 22 degrees, a year late, we finally begin to see new groups of sunspots emerging at the new active latitude.” Since the current minimum is now one year longer than usual, Howe and Hill conclude that the extended solar minimum phase may have resulted from the slower migration of the flow.

GONG and its sister instrument SOHO/MDI measure sound waves on the surface of the Sun. Scientists can then use the sound waves to probe structures deep in the interior of the star, in a process analogous to a sonogram in a medical office.

“Using the global sound wave inversions, we have been able to reveal the intimate connection between subtle changes in the Sun’s interior and the sunspot cycle on its surface,” said Hill.

“This is an important piece of the solar activity puzzle,” added Dean Pesnell, of NASA’s Goddard Space Flight Center. “It shows how flows inside the Sun are related to the creation of solar activity and how the timing of the solar cycle might be produced. None of the forecasting research groups predicted the current long extended delay in the new cycle. There is a lot more to learn in order to understand how the Sun creates magnetic fields.”

The new science of helioseismology, enabled by instruments such as the ground-based GONG, the Michelson Doppler Imager aboard the SOHO spacecraft, and NASA’s planned Solar Dynamics Observatory, has revolutionized understanding of the solar interior. “While the surface effects of the Sun’s torsional oscillations have been observed for some time, understanding of the dynamo and the origin of sunspots depend on measurements of the solar interior that are only possible
with helioseismic techniques,” said Hill.

Source: AAS Solar Physics Division Meeting (press release). Anne Minard is attending the meeting, and will report additional details from the teleconference on her blog at anneminard.com. Check back there after 2 p.m. Mountain. Also: check out this great movie!

June 1, 2009December 24, 2015 by Nancy Atkinson

Newsflash: Sunspot Appears!

Sunspot animation of Sunspot 1019. Credit: Spaceweather.com

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OK, I admit – the headline is a little over the top. But the sun has been so quiet of late, that even a small sunspot can be exciting. There’s been some debate whether this period of extreme solar calm is truly unusual, or just part of the natural cycle. But solar cycle models never predicted this low amount of activity. “It turns out that none of our models were totally correct,” admitted Dean Pesnell of the Goddard Space Flight Center, a member of an international panel of experts that are now trying to predict what the next solar cycle will hold. “The sun is behaving in an unexpected and very interesting way.”

The panel is predicting that the next cycle, Solar Cycle 24 will have a peak sunspot number of 90, the lowest of any cycle since 1928 when Solar Cycle 16 peaked at 78.

Right now, the solar cycle is in a valley–the deepest of the past century. In 2008 and 2009, the sun set Space Age records for low sunspot counts, weak solar wind, and low solar irradiance. The sun has gone more than two years without a significant solar flare.

“In our professional careers, we’ve never seen anything quite like it,” says Pesnell. “Solar minimum has lasted far beyond the date we predicted in 2007.”

For 2009, the number of “spotless” days are 123, as of May 31, which is 82%.

There’s a little sign of action on the sun, though. In recent months small sunspots and “proto-sunspots” are popping up with increasing frequency. Enormous currents of plasma on the sun’s surface (“zonal flows”) are gaining strength and slowly drifting toward the sun’s equator. Radio astronomers have detected a tiny but significant uptick in solar radio emissions. All these things are precursors of an awakening Solar Cycle 24 and form the basis for the panel’s new, almost unanimous forecast.

According to the forecast, the sun should remain generally calm for at least another year. This calm has a greater affect on Earth’s atmosphere than you might imagine. With low solar activity, the Earth’s atmosphere can cool and contract. Space junk accumulates in Earth orbit because there is less aerodynamic drag; hence the increase in the number of collision event “alarms” for the ISS and shuttles. The calm solar wind whips up fewer magnetic storms around Earth’s poles. Cosmic rays that are normally pushed back by solar wind instead intrude on the near-Earth environment. There are other side-effects, too, that can be studied only so long as the sun remains quiet.

But the sun is a very chaotic place, and even a below-average cycle is capable of producing severe space weather from solar flares and coronal mass ejections (CME) said Doug Biesecker of the NOAA Space Weather Prediction Center. So we shouldn’t be lulled into a false sense of security.

Sources: Science@NASA, SpaceWeather.com

May 1, 2009December 24, 2015 by Anne Minard

Cosmic Rays too Wimpy to Influence Climate

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People looking for new ways to explain climate change on Earth have sometimes turned to cosmic rays, showers of atomic nuclei that emanate from the Sun and other sources in the cosmos.

But new research, in press in the journal Geophysical Research Letters, says cosmic rays are puny compared to other climatic influences, including greenhouse gases — and not likely to impact Earth’s climate much.

Jeffrey Pierce and Peter Adams of Carnegie Mellon University in Pittsburgh, Pennsylvania, point out that cycles in numerous climate phenomena, including tropospheric and stratospheric temperatures, sea-surface temperatures, sea-level pressure, and low level cloud cover have been observed to correlate with the 11-year solar cycle.

However, variation in the Sun’s brightness alone isn’t enough to explain the effects and scientists have speculated for years that cosmic rays could fill the gap.

For example, Henrick Svensmark, a solar researcher at the Danish Space Research Institute, has proposed numerous times, most recently in 2007, that solar cosmic rays can seed clouds on Earth – and he’s seen indications that periods of intense cosmic ray bombardment have yeilded stormy weather patterns in the past.

Others have disagreed.

“Dust and aerosols give us much quicker ways of producing clouds than cosmic rays,” said Mike Lockwood, a solar terrestrial physicist at Southampton University in the UK. “It could be real, but I think it will be very limited in scope.”

To address the debate, Pierce and Adams ran computer simulations using cosmic-ray fluctuations common over the 11-year solar cycle.

“In our simulations, changes in [cloud condensation nuclei concentrations] from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties,” they write, “consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change.”

The results have met a mixed reception so far with other experts, according to an article in this week’s issue of the journal Science: Jan Kazil of the University of Colorado at Boulder has reported results from a different set of models, confirming that cosmic rays’ influence is similarly weak. But at least one researcher — Fangqun Yu of the University at Albany in New York — has questioned the soundness of Pierce and Adams’ simulations.

And so, the debate isn’t over yet …

Sources: The original paper (available for registered AGU users here) and a news article in the May 1 issue of the journal Science. See links to some of Svensmark’s papers here.