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.
Artist's interpretation depicting the new view of the heliosphere. The heliosheath is filled with “magnetic bubbles” (shown in the red pattern) that fill out the region ahead of the heliopause. In this new view, the heliopause is not a continuous shield that separates the solar domain from the interstellar medium, but a porous membrane with fingers and indentations. Credit: NASA/Goddard Space Flight Center/CI Lab
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The barrier at the edge of our Solar System may not be the smooth shield that scientists once thought. The venerable Voyager spacecraft have detected a huge, turbulent sea of magnetic bubbles in the heliosheath — the interface between the heliosphere and interstellar space — similar to an actively bubbling Jacuzzi tub. At a briefing today, scientists said the finding is significant as “we now will have to change our view of how the Sun interacts with the Solar System,” said Arik Posner, Voyager program scientist at NASA Headquarters. But it also means that the “force field” that surrounds the entire Solar System may be letting in more harmful cosmic rays and energetic particles than previously thought.
Over 30 years into their mission, the Voyagers are still monitoring their environment and sending back data. In 2007, scientists noticed that Voyager 1 recorded dramatic dips and rises in the amount of electrons it encountered as it traveled through the heliosphere, the barrier that surrounds the entire Solar System and is created by the Sun’s magnetic field. Voyager 2 made similar observations of these charged particles in 2008.
Computer simulation of the magnetic reconnection in the heliosheath, which look like bubbles, or sausages. Credit: NASA/J.F. Drake, M. Swisdak, M. Opher
Using a new computer model to analyze the data, scientists found the Sun’s distant magnetic field is likely made up of bubbles approximately 100 million miles (160 million kilometers) wide — “like long sausages,” said Merav Opher at the briefing, an astronomer at Boston University who is the lead author of a paper published in the Astrophysical Journal.
And the bubbles are moving around, with oscillations of plus or minus 10 to 20 km. “It is very bubbly as far as we can tell,” Jim Drake from the University of Maryland said at the press conference. “The entire thing is bubbly, like where the jets come out from a Jacuzzi.”
Opher said the bubbles, while not visible from Earth, cover a large portion of the sky at about 38 degrees latitude and as the solar winds “bumps” up against the heliopause, the bubbles fill up the entire region next to the heliopause.
Like Earth, our Sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward, and as the sun rotates, the solar wind twists them into a spiral as they are carried outward.
The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field.
These magnetic bubbles should act as electron traps, so the spacecraft would experience higher than normal electron bombardment as they traveled through the bubbles.
But the implications of this new finding, said Opher, is also that the heliosheath is very different from what scientists expected. She prefaced by saying that any earlier ideas about the region was only conjecture since no spacecraft has been there before. “We thought heliopause would be a smooth surface and shield us from intergalactic cosmic rays,” she said. “It is not a shield but more like a membrane that is a sea of bubbles.”
One argument would say the bubbles would seem to be a very porous shield, allowing lots of cosmic rays through the gaps. But another view would be that cosmic rays could get trapped inside the bubbles, making the bubbling froth a very good shield indeed.
However, the scientists are still working on figuring out exactly what these bubbles are. The Voyagers’ instruments, while still working fine, are being tested in this new region of space. “The magnetic instruments on Voyager were designed to measure magnetic fields, but they are right at very edge of what the instruments are capable of sensing,” said Drake. “The magnetic field is very weak. While trying to find out what these magnetic bubbles are, we haven’t reached that moment where we say, ‘yes, that is it.’ We’d like to be able to pin it down much better.”
This video from NASA’s Goddard Spaceflight Center helps to visually explain the new findings:
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.
Four views of Endeavour docked to the ISS on May 29, 2011. Credit: Thierry Legault and Emmanuel Rietsch
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Award-winning French astrophotographer Thierry Legault traveled through Germany, France and Spain during Endeavour’s final mission to find clear skies and good seeing to capture the shuttle’s voyage to the International Space Station. While he told us it wasn’t easy, the results are incredible! The visible detail of the shuttle and parts of the International Space Stations is absolutely amazing. You can see the newly installed Alpha Magnetic Spectrometer in one shot, as well as the open payload bay doors on Endeavour in another. The video Legault shot is available on his website, and he has unique 3-D versions as well.
Below are some of his trademark views of transits of the Sun by ISS and Endeavour, with one showing the shuttle just before it docked to the station.
Solar transit taken on May 18th from Essen, Germany through thick clouds showing Endeavour a few minutes before docking to the ISS. Transit duration was 0.7 seconds. Credit: Thierry Legault.
Legault told us he was chasing the shuttle and the station from different parts of Europe, however because of weather problems (clouds and turbulence) he was not very happy with the results. But this image is stunning anyway even though clouds dimmed available light by more than 100 times, Legault said. What is perhaps most amazing is that the transit time for this pass in front of the Sun was 0.7 seconds!
Here’s a less cloudy view taken on May 25:
A close-up view of Endeavour and the ISS transiting the sun on May 25th from France. Transit duration was 0.5 seconds. Credit: Thierry Legault.
And the full view for reference. This transit was only a half second!
Solar transit taken on May 25th from France (Orleans), showing Endeavour docked to the ISS. Credit: Thierry Legault. Series of transits taken on May 20, 22 and 23, 2011 from different areas of France, showing variations of orientation of the ISS with Endeavour docked. On May 23, the ISS passes besides a sunspot which is larger than the Earth. Credit: Thierry Legault
All transit images were taken with Takahashi TOA-150 6″ apochromatic refractor (focal length 2400mm and 3600mm) on EM-400 mount, Baader Herschel wedge. Nikon D3X at 1/8000s, 100 ISO, working in continuous shooting at 5 frames per second during 5 seconds.
Frames from videos taken from Spain (May 31) and France (June 1) 90 minutes before deorbit burn. Credit: Thierry Legault and Emmanual Rietsch.
Here are frames from videos taken by Legault and fellow astrophotographer Emmanual Rietsch just prior to the deorbit burn for landing on June 1. The video of these shots, as well as more images are also available on Legault’s website.
Thanks to Thierry for sending Universe Today these amazing images and allowing us to post them!
Soon you may see an eerie spectacle on clear summer nights if you are located at latitudes between 50° and 70° north and south of the equator: Noctilucent Clouds.
These ghostly apparitions are a delight to see and are quite rare. It is incredibly difficult to predict exactly when they will appear, but we do know they should begin to appear soon.
The season for Noctilucent Clouds (Noctilucent = Latin for “Night Shining”) starts early June and continues into late July. They are seen just after dusk, or before dawn and an apparition can last around an hour.
These mysterious clouds, with their bizarre tenuous wispy shapes reminiscent of ripples in sand or the changing surface of a pool of water, spread like a glowing web across the northern sky. Colours can range from brilliant whites, with tinges of blue, pink and orange.
Formed by tiny ice crystals, they are the highest clouds in the Earth’s atmosphere, located in the mesosphere at altitudes of around 76 to 85 kilometers (47 to 53 miles) almost at the edge of space.
They are normally too faint to be seen, and are visible only when illuminated by sunlight from below the horizon, while the lower layers of the atmosphere are in the Earth’s shadow. Noctilucent clouds are not fully understood and are a recently discovered meteorological phenomenon, only being recorded for about 120 years.
Noctilucent clouds can only form under very restrictive conditions, and their occurrence can be used as a guide to changes in the upper atmosphere. Since their relatively recent classification, the occurrence of noctilucent clouds appears to be increasing in frequency, brightness and extent.
There is evidence that the relatively recent appearance of noctilucent clouds and their gradual increase, may be linked to climate change. Another recent theory is that some of these bright displays come from particulates and water vapour in the atmosphere left over from Space Shuttle launches.
How can you see them? Over the next couple of months look north during dusk and dawn and try and spot this mysterious and elusive phenomenon. They are best seen when the sun is between 6 and 16 degrees below the horizon, and seem to occur more frequently in the Northern hemisphere than the Southern.
Good luck!
Noctilucent clouds over Blair, Nebraska, USA. Credit: Mike Hollingshead
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.
The SOHO spacecraft coronagraph captured a sun-diving comet on May 10th and 11th that met its demise as it plunged into the Sun just as Old Sol released a huge flare. The two events were coincidental and not related, but spectacular to see.
The Solar Dynamics Observatory captured some plasma streaming off the Sun, doing a quick dance, and diving back into the surface. This video zooms into an active region over two days (Apr. 30 – May 2, 2011). The cloud of ionized gas, or plasma that comes off the Sun is caused by an active, erupting sunspot. Why does the plasma return instead of streaming off into space? Magnetic forces are pulling the material along magnetic field lines on the Sun, and the plasma follows the Sun’s magnetic fields as it flies outwards, and either returns to the Sun or goes out into space. Here, the plasma returned. What you are seeing is ionized Helium at about 60,000 degrees C. in extreme ultraviolet light.
