The Sun on July 11, 2011. Credit: Cesar Cantu from Monterrey, Mexico, and the Chilidog Observatory. Click for high resolution version.
Interesting activity captured on the Sun early today (July 12, 2011) showing an active region on the Sun’s Eastern limb. Plasma was hurled very high above the stellar surface, but didn’t have the needed escape velocity and most of the plasma “rained” back down in a fountain. The video shows the activity in different wavelengths.
See below for more views, including the first time a sun-grazing comet was seen disintegrating over the Sun’s surface.
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This great ground-based look at the Sun is from July 11, 2011. “A sun a little more active than the past few days, although with much mist in the city, making it impossible to get photos of larger increases,” said Cesar Cantu from Monterrey, Mexico, with his Chilidog Observatory. See more at his website, Astronomía Y Astrofotografía.
The Solar Dynamics Observatory AIA imager spotted a sun-grazing comet zooming across the face of the sun and disintegrating over about a 15 minute period on July 6, 2011. This has never observed before. It’s a little difficult to see, but look closely as a line of light appears in the right just off the edge of the Sun and move across to the left. The angle of the comet’s orbit brought it across the front half of the Sun.Given the intense heat and radiation, the comet simply evaporated away completely. SDO scientists say the comet was probably a member of the Kreutz sun-grazer family. The AIA imager took this video in extreme ultraviolet.
Within our own lives, one of the most powerful forces is that of the Sun. Directly or indirectly, it provides all of the energy we use on a daily basis. Yet this mass of incandescent plasma is often a mere afterthought. But not to be forgotten, writer for Astronomy magazine, Bob Berman makes the Sun the focus of a new book, The Sun’s Heartheat which explores how our parent star affects our lives in ways more direct than we might expect. The book is due to be released July 13th, but I got a review copy to tell everyone about.
The book is a short read clocking in at a quick 20 chapters. Roughly the first third of them is a brief history of solar astronomy. Most of this is concentrated on the history of observations of sunspots. It goes through the initial discoveries, the waxing and waning of popularity of sunspots thanks to the Maunder minimum, and Schwabe’s discovery of the cycles.
Once that’s ironed out, we get to what I consider to be the main theme of the book: How does the Sun affect us here on Earth? The first topics addressed are rather germane: The sun brings life, but too much of it can kill you. But after that, the topics are a bit more interesting. There’s a fantastic chapter on the importance of getting adequate supplies of vitamin D which your body produces naturally from exposure to the Sun. Another chapter deals with the way the Sun doesn’t affect us: Astrologically. The book discusses our ability to see colors and the impressiveness of total solar eclipses and auroras.
The second to last chapter covers just how much peril we face from a large coronal mass ejection. I was familiar with nearly everything in the book, including this chapter, but I think this chapter was my favorite. Sadly, most people are disinterested in science, but more than any other, this one was tangible enough to be rather alarming.
It closes with a preview of the future Sun, describing how its slow increase in brightness will make life on Earth unfavorable in a billion years or so and how it will eventually expand into a red giant.
If you’re an experienced astronomy enthusiast, this book will likely offer little new information on the Sun itself, although it does have lots of good backstories on some of the discoveries and those involved. It is engaging thanks to a friendly tone, even if Berman does have an odd fascination with anachronisms (17th century HMO’s?). The book lacked several of the deeper topics that I feel could have been more inviting for advanced readers such as a more thorough description of our knowledge of the innards of the Sun thanks to helioseismology. I suspect this is because it didn’t relate strongly enough to the main thesis aside from a general, how the Sun works which doesn’t focus on how it affects us.
But if you know a young astronomer, or someone older just getting into the field, or someone that’s stared only at deep sky objects and never thought much about the closest star to home, this book would likely be of some interest.
The Halo coronal mass ejection (CME) as viewed by the Solar and Heliospheric Observatory coronograph on June 21, 2011. Credit: NASA/SOHO
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Late in the evening on June 20, 2011 the Sun emitted a long lasting C7.7 class flare (a relatively small flare) that peaked around 11:25p.m. EDT. The flare was associated with a coronal mass ejection that bloomed off the sun at 11:09p.m. EDT (0412 UT).
Spaceweather.com reports that according to analysts at the Goddard Space Flight Center Space Weather Lab, the CME left the sun traveling 800 km/s and it will reach Earth on June 23rd at 23:22 UT (plus or minus 7 hours). A very cool 3D heliospheric model (below) shows the cloud sweeping past our planet. The impact is expected to trigger a G2-class geomagnetic storm.
High-latitude sky watchers should be alert for auroras on June 23rd and 24. The season favors southern hemisphere observers, where skies are darker for longer due to the winter solstice.
These 3D Heliospheric animated models, developed by the Community Coordinated Modeling Center based at the Goddard Space Flight Center, show how the CME cloud might appear as it sweeps past Earth. Credit: NASA/CCMC
June 21st, 2011 is Summer Solstice – the longest day of the year.
This is the time when the Sun is at its highest or most northerly point in the sky in the Northern Hemisphere and when we receive the most hours of daylight. If you live in the Southern Hemisphere it is the reverse, so you will be having “Winter Solstice.”
Also known as “Midsummer” the Summer Solstice gets its name from the Latin for sol (sun) and sistere (to stand still). The Sun reaches its most Northerly point and momentarily stands still before starting its journey South in the sky again until it reaches its most Southerly point “Winter Solstice”, before repeating the cycle. This is basically how we get our seasons.
It’s not actually the Sun that moves North or South over the seasons although it may appear so. It’s the Earths axial tilt that causes the Sun to change position in the sky as the Earth orbits the Sun throughout the year.
The angle of the Sun and the Earth's seasons. Image credit: NASA
Summer Solstice/ Midsummer is steeped in ancient folklore especially in Northern Europe with the most famous place directly related to it being Stonehenge, where the sun has been worshiped for thousands of years.
Stonehenge Credit: bistrochic.net
The Sun reaches its most Northerly point in the sky at 17:16 UTC momentarily and from that point forward starts to make its way South. This means the days will get shorter and shorter until Winter Solstice in December.
Our Sun on June 6, 2011. Credit: Credit: Cesar Cantu from the Chilidog Observatory in Monterrey, Mexico.
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Are we headed into the 21st century version of the Maunder Minimum? Three researchers studying three different aspects of the Sun have all come up with the same conclusion: the Sun’s regular solar cycles could be shutting down or going into hibernation. A major decrease in solar activity is predicted to occur for the next solar cycle (cycle #25), and our current solar cycle (#24) could be the last typical one. “Three very different types of observations all pointing in the same direction is very compelling,” said Dr. Frank Hill from the National Solar Observatory, speaking at a press briefing today. “Cycle 24 may be the last normal one, and 25 may not even happen.”
Even though the Sun has been active recently as it heads towards solar maximum in 2013, there are three lines of evidence pointing to a solar cycle that may be going on hiatus. They are: a missing jet stream, slower activity near the poles of the sun and a weakening magnetic field, meaning fading sunspots. Hill, along with Dr. Richard Altrock from the Air Force Research Laboratory and Dr. Matt Penn from the National Solar Observatory independently studied the different aspects of the solar interior, the visible surface, and the corona and all concur that cycle 25, will be greatly reduced or may not happen at all.
Solar activity, including sunspot numbers, rises and falls on average about every 11 years – sometimes the cycles are as short as 9 years, other times it is as long as 13 years. The Sun’s magnetic poles reverse about every 22 years, so 11 years is half of that magnetic interval cycle.
"Butterfly diagram" shows the position of sunspots over 12 solar cycles. Sunspots emerge over a range of latitudes centered on migratory jet streams that follow a clear pattern, trending from higher latitudes to lower latitudes on the Sun. The active latitudes are associated with mobile zonal flows or "jet streams" that vary through the cycle. Credit: SWRI
The first line of evidence is a slowing of a plasma flow inside the Sun, an east/west flow of gases under the surface of the Sun detected via seismology with spacecraft like the Solar Dynamics Observatory (SDO)or SOHO and also with the Global Oscillation Network Group (GONG) observing stations, a system that measures pulsations on the solar surface to understand the internal structure of the sun. The flow of plasma normally indicates the onset of sunspot formation for the next solar cycle. While this river ebbs and flows during the cycle, the “torsional oscillations,” — which starts at mid-latitudes and migrates towards the equator — and normally begins forming for the next solar cycle has not yet been detected.
Latitude-time plots of jet streams under the Sun's surface show the surprising shutdown of the solar cycle mechanism. New jet streams typically form at about 50 degrees latitude (as in 1999 on this plot) and are associated with the following solar cycle 11 years later. New jet streams associated with a future 2018-2020 solar maximum were expected to form by 2008 but are not present even now, indicating a delayed or missing Cycle 25. Credit: SWRI
Hill said the above graphic is key for understanding the issue. “The flow for Cycle 25 should have appeared in 2008 or 2009 but it has not and we see no sign of it,” he said. “This indicates that the start of Cycle 25 may be delayed to 2021 or 2022, with a minimum great that what we just experienced, or may not happen at all.”
Plots of coronal brightness against solar latitude show a "rush to the poles" that reflects the formation of subsurface shear in the solar polar regions. The current "rush to the poles" is delayed and weak, reflecting the lack of new shear under the photosphere. Note the graph depicts both north and south hemispheres overlaid into one map of solar magnetic activity, and that the patterns correspond with the butterfly diagram above. Credit: SWRI
The second line of evidence is slowing of the “rush to the poles,” the rapid poleward march of magnetic activity observed in the Sun’s faint corona. Altrock said the activity in the solar corona follows same oscillation pattern described by Hill, and that they have been observing the pattern for about 40 years. The researchers now see a very weak and slow pattern in this movement.
“A key thing to understand is that those wonderful, delicate coronal features are actually powerful, robust magnetic structures rooted in the interior of the Sun,” Altrock said. “Changes we see in the corona reflect changes deep inside the Sun.”
In a well-known pattern, new solar activity emerges first at about 70 degrees latitude at the start of a cycle, then towards the equator as the cycle ages. At the same time, the new magnetic fields push remnants of the older cycle as far as 85 degrees poleward. “In previous solar cycles, solar maximum occurred when the rush to the poles reached an average latitude of 76 degrees,” Altrock said. “Cycle 24 started out late and slow and may not be strong enough to create a rush to the poles, indicating we’ll see a very weak solar maximum in 2013, if at all. It is not clear whether solar max as we know it.”
Altrock added that if the “rush” doesn’t occur, no one knows what will happen in the future because no one has modeled what takes place without this rush to the poles.
Average magnetic field strength in sunspot umbras has been steadily declining for over a decade. The trend includes sunspots from Cycles 22, 23, and (the current cycle) 24. Credit: SWRI
The third line of evidence is a long-term weakening trend in the strength of sunspots. Penn, along with his colleague William Livingston predict that by Cycle 25, magnetic fields erupting on the Sun will be so weak that few if any sunspots will be formed.
Using more than 13 years of sunspot data collected at the McMath-Pierce Telescope at Kitt Peak in Arizona, Penn and Livingston observed that the average field strength declined about 50 gauss per year during Cycle 23 and now in Cycle 24. They also observed that spot temperatures have risen exactly as expected for such changes in the magnetic field. If the trend continues, the field strength will drop below the 1,500 gauss threshold and spots will largely disappear as the magnetic field is no longer strong enough to overcome convective forces on the solar surface.
“Things are erupting on the sun,” Penn said, “but they don’t have the energy to create sunspots.”
But back in 1645-1715 was the period known as the Maunder Minimum, a 70-year period with virtually no sunspots. The Maunder Minimum coincided with the middle – and coldest part – of the Little Ice Age, during which Europe and North America experienced bitterly cold winters. It has not been proven whether there is a causal connection between low sunspot activity and cold winters. However lower earth temperatures have been observed during low sunspot activity. If the researchers are correct in their predictions, will we experience a similar downturn in temperatures?
Hill said that some researchers say that the Sun’s activity can also play a role in climate change, but in his opinion, the evidence is not clear-cut. Altrock commented he doesn’t want to stick his neck out about how the Sun’s declining activity could affect Earth’s climate, and Penn added that Cycle 25 may provide a good opportunity to find out if the activity on the Sun contributes to climate change on Earth.
Lead image thanks to César Cantú in Monterrey, Mexico at the Chilidog Observatory. See more at his website, Astronomía Y Astrofotografía.
You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.
First complete image of the far side of the sun taken on June 1, 2011. Click image for larger version. Credit: NASA/STEREO.
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Far out! This is the first complete image of the solar far side, the half of the sun invisible from Earth. Captured on June 1, 2011, the composite image was assembled from NASA’s two Solar TErrestrial RElations Observatory (STEREO) spacecraft. STEREO-Ahead’s data is shown on the left half of image and STEREO-Behind’s data on the right.
You may recall that the two STEREO spacecraft reached opposition (180 degree separation) on February 6 of this year and the science team released a “complete” 360 degree view of the Sun. However, a small part of the sun was inaccessible to their combined view until June 1. This image represents the first day when the entire far side could be seen.
The image is aligned so that solar north is directly up. The seam between the two images is inclined because the plane of Earth’s – and STEREO’s – orbit, known as the “ecliptic”, is inclined with respect to the sun’s axis of rotation. The data was collected by STEREO’s Extreme Ultraviolet Imagers in the SECCHI instrument suites.
The video below explains why seeing the entire Sun is helpful to scientists:
Surfer waves -- initiated in the sun, as they are in the water, by a process called a Kelvin-Helmholtz instability -- have been found in the sun's atmosphere. Credit: NASA/SDO/Astrophysical Journal Letters
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Surf’s up on the Sun! Our favorite gnarly spacecraft, the Solar Dynamics Observatory (SDO) has caught conclusive evidence of classic “surfer waves” in the Sun’s atmosphere. But these waves trump ‘Hawaii Five-O’ surfing big time, as they are about the same size as the continental U.S. Spotting these waves will help our understanding of how energy moves through the solar atmosphere, known as the corona and maybe even help solar physicists be able to predict events like Coronal Mass Ejections.
Just like a surfing wave on Earth, the solar counterpart is formed by the same fluid mechanics — in this case it is a phenomenon known as a Kelvin-Helmholtz instability. Since scientists know how these kinds of waves disperse energy in water, they can use this information to better understand the corona. This in turn, may help solve an enduring mystery of why the corona is thousands of times hotter than originally expected.
“One of the biggest questions about the solar corona is the heating mechanism,” says solar physicist Leon Ofman of NASA’s Goddard Space Flight Center, Greenbelt, Md. and Catholic University, Washington. “The corona is a thousand times hotter than the sun’s visible surface, but what heats it up is not well-understood. People have suggested that waves like this might cause turbulence which cause heating, but now we have direct evidence of Kelvin-Helmholtz waves.”
Even though these waves occur frequently in nature here on Earth, no one had seen them on the Sun. But that was before SDO.
Ofman and colleagues spotted these waves in images taken on April 8, 2010 in some of the first images caught on camera by SDO, which launched in Feburary last year and began capturing data on March 24, 2010. Ofman & team have just published a paper in Astrophysical Journal Letters.
Kelvin-Helmholtz instabilities occur when two fluids of different densities or speeds flow by each other. In the case of ocean waves, that’s the dense water and the lighter air. As they flow past each other, slight ripples can be quickly amplified into the giant waves loved by surfers. In the case of the solar atmosphere, which is made of a very hot and electrically charged gas called plasma, the two flows come from an expanse of plasma erupting off the sun’s surface as it passes by plasma that is not erupting. The difference in flow speeds and densities across this boundary sparks the instability that builds into the waves.
On the sun, the two fluids are both plasmas — expanses of super hot, charged gases — which interact. One is erupting from the surface and shooting past a second plasma that is not erupting. The resulting turbulence is a Kelvin-Helmholtz wave form.
The erupting plasma is likely from a Coronal Mass Ejection, such as was seen earlier this week, where the Sun violently propels massive amounts of high-speed plasma particles into space. So, knowing more about the how the corona is heated and what the conditions are just before the KH waves form might give scientists the ability to predict a the next CME, which is a long-standing goal of solar scientists.
But figuring out the exact mechanism for heating the corona will likely keep solar physicists busy for quite some time. However, SDO’s ability to capture images of the entire sun every 12 seconds with such precise detail will certainly provide the data needed.
You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.
Massive coronal mass ejection on. This image shows the size of the Earth to scale. NASA / SDO / J. Major.
Here’s more video from the huge explosion on the Sun on June 7, 2011, which began at about 06:41 UTC. Not only was this event one of the most spectacular ever recorded, but also one of the best observed, with complementary data from several spacecraft and different vantage points. This video shows data from three different space observatories. The Solar Dynamics Observatory’s Atmospheric Imaging Assembly recorded the amazing event in stunning detail in different wavelengths. Additionally, the Solar & Heliospheric Observatory’s (SOHO) LASCO coronagraph and STEREO’s (Solar Terrestrial Relations Observatory) SECCHI instrument suite observed the prominence and associated CME as they traveled out into the heliosphere. Using LASCO and SECCHI data, the speed of the leading edge of the CME was estimated to be in the range 1200 – 1600 km/s. Model calculations predict that Earth will receive a glancing blow of the CME on June 10, possibly sparking some nice aurorae at high latitudes, according to the SDO team.
The citizen science project Solar Storm Watch predicts a solar storm to reach Earth at 08:00 UTC on June 10, 2011 with a glancing blow 35 degrees behind Earth, with a second storm expected at 19:00 UTC on June 10, 2011, with another glancing blow 32 degrees behind Earth.
The event originated from the almost spotless active region 11226 and was associated with a moderate M2-class X-ray flare. The CME and associated shock wave produced and S1-class radiation storm, which shows up as speckles in the LASCO movies.
The size of the prominence is thought to be at least 75 times the size of Earth. Our Jason Major created a graphic showing the size comparison. Earth is the little teeny tiny blue circle in the top left corner:
A huge and spectacular prominence eruption on the Sun, June 7, 2011. Credit: NASA/Solar Dynamics Observatory
Early this morning (June 7, 2011) an amazingly massive and spectacular event took place on the Sun; a huge prominence eruption, marked by a solar flare and release of energetic particles. Daniel Pendick from the Geeked on Goddard blog described it as a “fountain of plasma that blasts out of the solar surface, spreads outward, and collapses to splat back down.”
“I’ve never seen material released like this before, such a huge amount that falls back down in such a spectacular way,” says Dr. C. Alex Young in the video. “It looks like someone just kicked a giant clod of dirt into the air and it fell back down.” Young added that this event will probably not cause any problems as far as space weather affecting Earth.
Below are some still images of the event from the Solar Dynamics Observatory and (just added at 1755 UTC) a video from SDO showing the event in several different wavelengths.
These images were posted by the Camilla_SDO Twitpic feed.
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This is the peak of the M2.5 class solar flare, which propelled the plasma into space today. Credit: NASA/ Solar Dynamics Observatory, via CamillaSDO on Twitter.
The SDO science teams says: “The Sun unleashed an M-2 (medium-sized) solar flare with a substantial coronal mass ejection (CME) on June 7 that is visually spectacular. The large cloud of particles mushroomed up and fell back down looking as if it covered an area of almost half the solar surface.”
“SDO observed the flare’s peak at 1:41 AM EST. SDO recorded these images in extreme ultraviolet light and they show a very large explosion of cool gas. It is somewhat unique because at many places in the eruption there seems to be even cooler material — at temperatures less than 80,000K.”
Update: The US National Weather Service Space Weather Prediction center has now warned that the solar flare, one of the largest to occur since December 2006, will likely lead to gemagnetic storm activity tomorrow, Wednesday.
The NWS stated: “A dramatic eruption from an otherwise unimpressive NOAA Region 1226 earlier today is expected to cause G1 (minor) to G2 (moderate) levels of geomagnetic storm activity tomorrow, June 8, beginning around 1800 UTC with the passage of a fast CME. A prompt Solar Radiation Storm reached the S1 (minor) level soon after the impulsive R1 (minor) Radio Blackout at 0641 UTC. The Solar Radiation Storm includes a significant contribution of high energy (>100 MeV) protons, the first such occurrence of an event of that type since December 2006.”
You can find updates from the Space Weather Prediction Center at this link.
Here’s the reason for those auroras Tammy was talking about…The Solar Dynamics Observatory captures a beautiful filament eruption from the Sun in the early hours of May 17, 2011 which sent a cloud of plasma into space. This Coronal Mass Ejection was not aimed at Earth but it will likely interact with Earth’s magnetic field by the 19th, so be on the lookout for auroras. The second part of the video is from today, May 18, 2011 and shows some dancing plasma and more “plasma rain” similar to what we showed a last week. few days ago. The Sun’s gravity grabs and pulls the plasma back, even when it appears ready to travel off into space.
