A filament partially blocks SDO's view of erupting plasma on Dec. 9. (NASA/SDO)
A video posted today by the team at NASA’s Solar Dynamics Observatory shows two recent events on the Sun: a twisting prominence and the “eclipse” of a plasma eruption by the structure of a darker, cooler filament. Most impressive!
From the SDO team:
Over the past 24 hours we have seen some beautiful solar events. None of them have a direct impact on Earth, but they are astonishing to watch. It just shows how an active star our Sun really is… far from boring!
On December 8, 2011 a twisting prominence eruption occurred on the lower eastern limb. The view through the AIA 304 angstrom filter shows us this beautiful eruption.
A filament partially blocks SDO's view of erupting plasma on Dec. 9. (NASA/SDO)In the early hours of December 9, 2011 SDO observed a little bit of a different eclipse. An erupting cloud of plasma was eclipsed by a dark magnetic filament. The eruption is still on the far side of the Sun, behind the eastern limb and is slowly moving forward and over the limb sometime next week.
In front you can observe the filament of relatively cool dark material floating across the Sun’s surface in the foreground. That filament partially blocks the view of the hot plasma eruption behind it.
Excellent footage of our constantly-active Sun! It’s easy to forget too that these events and structures are many, many times larger than our entire planet… the sheer power of a star is quite an impressive thing to see. Thanks to SDO we get an unblinking front-row seat to all the action!
Coronal Mass Ejection as viewed by the Solar Dynamics Observatory on June 7, 2011. A similar type of outburst triggered aurorae during a strong geomagnetic storm in February 1872. Image Credit: NASA/SDO
[/caption]According to a new set of NASA computer simulations, solar storms and Coronal Mass Ejections (CMEs) can erode the lunar surface. Researchers speculate that not only can these phenomena erode the lunar surface, but could also be a cause of atmospheric loss for planets without a global magnetic field, such as Mars.
A team led by Rosemary Killen at NASA’s Goddard Space Flight Center, has written papers exploring different aspects of these phenomena and will appear in an issue of the Journal of Geophysical Research Planets. The team’s research was also presented earlier this week during the fall meeting of the American Geophysical Union.
What are CME’s? Corona Mass Ejections are intense outbursts of the Sun’s usually normal solar wind which consists of electrically charged particles (plasma). CME’s blow outward from the surface of the Sun at speeds in excess of 1.6 million kilometers per hour into space and can contain over a billion tons of plasma in a cloud larger than Earth.
Our Moon has the faintest traces of an atmosphere, which is technically referred to as an exosphere. The lack of any significant atmosphere, combined with the lack of a magnetic field, makes the lunar surface vulnerable to the effects of CME’s.
William Farrell, DREAM (Dynamic Response of the Environment at the Moon) team lead at NASA Goddard, remarked, “We found that when this massive cloud of plasma strikes the Moon, it acts like a sandblaster and easily removes volatile material from the surface. The model predicts 100 to 200 tons of lunar material – the equivalent of 10 dump truck loads – could be stripped off the lunar surface during the typical 2-day passage of a CME.”
While CME’s have been extensively studied, Farrell’s research is the first of its kind that attempts to predict the effects of a CME on the Moon. “Connecting various models together to mimic conditions during solar storms is a major goal of the DREAM project” added Farrell.
When intense heat or radiation is applied to a gas, the electrons can be removed, turning the atoms into ions. This process is referred to as “ionization”, and creates the fourth form of matter, known as plasma. Our Sun’s intense heat and radiation excites gaseous emissions, thus creating a solar wind plasma of charged particles. When plasma ions eject atoms from a surface, the process is called “sputtering”.
The lead author of the research paper Rosemary Killen described this phenomenon: “Sputtering is among the top five processes that create the Moon’s exosphere under normal solar conditions, but our model predicts that during a CME, it becomes the dominant method by far, with up to 50 times the yield of the other methods.”
Images from computer simulations of the lunar calcium exosphere during a CME (left) and the slow solar wind (right). Red and yellow indicate a relatively high abundance of calcium atoms while blue, purple, and black indicate a low abundance. The CME produces a much denser exosphere than the slow solar wind. Image Credit: NASA / Johns Hopkins University
In an effort to better test the team’s predictions, studies will be performed using NASA’s Lunar Atmosphere And Dust Environment Explorer (LADEE). Scheduled to launch in 2013 and orbit the Moon, the team is confident that the strong sputtering effect will send atoms from the lunar surface to LADEE’s orbital altitude (20 to 50 km).
Farrell also added, “This huge CME sputtering effect will make LADEE almost like a surface mineralogy explorer, not because LADEE is on the surface, but because during solar storms surface atoms are blasted up to LADEE.”
Affecting more than just our Moon, solar storms also affect Earth’s magnetic field and are the root cause of the Northern and Southern lights (aurorae). The effect solar storms have on Mars is a bit more significant, due in part to the Red Planet’s lack of a planet-wide magnetic field. It is widely theorized that this lack of a magnetic field allows the solar wind and CME’s to erode the martian atmosphere. In late 2013, NASA will launch the Mars Atmosphere and Volatile Evolution (MAVEN) mission. The goal of MAVEN is to orbit Mars and help researchers better understand how solar activity, including CMEs, affects the atmosphere of the red planet.
The Voyager 1 spacecraft has started to transverse what JPL has dubbed as a "cosmic purgatory" between our solar system - and interstellar space. Image Credit: NASA/JPL
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Voyager 1 is in uncharted territory. The long-lived spacecraft has entered a new region of space that lies between where our solar system ends and where interstellar space begins. This area is not a place of sightseeing however, as a NASA press release referred to it as a kind of “cosmic purgatory.”
Here, the solar winds ebb somewhat, the magnetic field increases and charged particles from within our solar system – is leaking out into interstellar space. This data has been compiled from information received from Voyager 1 over the course of the last year.
The Voyager spacecraft's compliment of scientific instruments have provided scientists back on Earth with information about what the space environment at the fringes of our sun's influence is truly like. Image Credit: NASA/JPL - Caltech
“Voyager tells us now that we’re in a stagnation region in the outermost layer of the bubble around our solar system,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. “Voyager is showing that what is outside is pushing back. We shouldn’t have long to wait to find out what the space between stars is really like.”
Despite the fact that Voyager 1 is approximately 11 billion miles (18 billion kilometers) distant from the sun – it still has not encounter interstellar space. The information that scientists have gleaned from the Voyager 1 spacecraft indicates that the spacecraft is still located within the heliosphere. The heliosphere is a “bubble” of charged particles that the sun blows around itself and its retinue of planets.
Voyager 1 has traveled far past the realm of the gas or even ice giants and is now in uncharted territory where scientists are learning more and more about the dynamic environment at the far-flung edges of our solar system. Image Credit: NASA/JPL - Caltech
The latest findings were made using Voyager’s Low Energy Charged Particle instrument, Cosmic Ray Subsystem and Magnetometer.
Experts are not certain how long it will take the Voyager 1 spacecraft to finally breach this bubble and head out into interstellar space. Best estimates place the length of time when this could happen anywhere from the next few months – to years. These findings counter findings announced in April of 2010 that showed that Voyager 1 had essentially crossed the heliosphere boundary. The discoveries made during the past year hint that this region of space is far more dynamic than previously thought.
Voyager 1 has entered into a region of space between the sun's influence and the beginning of interstellar space that NASA has dubbed the "stagnation region." Image Credit: NASA/JPL - Caltech
The magnetometer aboard Voyager 1 has picked up an increase in the intensity of the magnetic field located within this “stagnation field.” Essentially the inward pressure from interstellar space is compressing the magnetic field to twice its original density. The spacecraft has also detected a 100-fold increase in the intensity of high-energy electrons diffusing into our solar system from outside – this is yet another indicator that Voyager 1 is approaching the heliosphere.
The interplanetary probe was launched from Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) on Sept. 5, 1977, Voyager 1’s sister ship, Voyager 2 is also in good health and is about 9 billion miles (15 billion kilometers) from the sun (it too was launched in 1977). The spacecraft itself was built by NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“Voyager is a mission of discovery and it’s at the edge of the solar system still making discoveries,” said Stone said. “The stagnation is the latest in the whole journey of discovery. We are all excited because we believe it means we’re getting very close to boundary of heliosphere and the entry into interstellar space.”
Both of the Voyager spacecraft were thrust to orbit by the powerful Titan boosters - and both in the same year - 1977. Photo Credit: NASA
Annular solar eclipse observed by the Hinode spacecraft on Jan. 6, 2011. Credit: Hinode/XRT
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While many in the U.S. will be recovering from Thanksgiving day meals and looking for ways to stretch their holiday shopping dollars at (hopefully local) retailers’ “Black Friday” sales, the face of the Sun will grow dark as the Moon passes in front of it, casting its shadow over the Earth. But it won’t be visible to American shoppers – or very many people at all, in fact… this eclipse will be hiding in the southern skies above Antarctica!
Visibility of Nov. 25 2011 annular eclipse. NASA GFSC
On Friday, November 25, an annular eclipse will occur, reaching a maximum coverage at 06:20:17 UT of magnitude .905. It will be the largest – and last – partial eclipse of the year.
But its visibility will be limited to the most southern latitudes… outside of the Antarctic continent, only New Zealand, Tasmania and parts of South Africa will have any visibility of the event.
An annular eclipse is similar to a total eclipse, except that the Moon is at a further distance from Earth in its orbit and so does not completely cover the disc of the Sun. Instead a bright ring of sunlight remains visible around the Moon’s silhouette, preventing total darkness.
The next solar eclipse will occur on May 20, 2012. It will also be annular, and even darker than the Black Friday one at a magnitude of .944. It will be visible from China, Japan, the Pacific and Western U.S.
Following that, the main event of 2012 would have to be a total eclipse on November 13, which will be visible from Australia, New Zealand and South America (greatest totality will occur over the South Pacific.) Several sites have already set up group travel events to witness it!
Feeling left out on cosmic occultations? Not to worry… there will be a very visible total lunar eclipse on the night of December 10, 2011 (weather permitting, of course) to viewers across the Northern Hemisphere. The Moon will pass into Earth’s shadow, turning gradually darker in the night sky until it is colored a deep rusty red. It’s a wonderful event to watch, even if not as grandiose as a total eclipse of the Sun.
(Plus it’s completely safe to look at, as opposed to solar eclipses which should never be directly observed without safety lenses or some projection device… for the same reasons that you shouldn’t stare at the Sun normally.)
For a listing of past and future eclipses, both solar and lunar, visit Mr. Eclipse here. And you can read more about the Nov. 25 eclipse on AstroGuyz.com.
A large protuberance on the Sun, from Nov. 13, 2011. Credit: César Cantú, Chilidog Observatory.
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A huge wall of plasma rose from the Sun’s southeast limb over the weekend, with what might be one of the biggest prominences seen in many years. César Cantu from Monterrey, Mexico, took the image above, adding an “Earth” for reference of how big this prominence really is. A solar prominence is a large, bright feature extending outward from the Sun’s surface. Prominences are anchored to the Sun’s surface in the photosphere, and can loop hundreds of thousands of kilometers into space.
Leonard Mercer from Malta sent us the image below, saying “I never encountered such a huge prominence since I started imaging the Sun.”
A mosaic of 4 images taken of the Sun on Nov. 13, 2011. Credit: Leonard Mercer.
As large as this prominence is, there was also another even larger feature on the Sun. A filament (which is a prominence that is viewed against the solar disk) on the upper left snakes across the Sun’s surface, stretching more than a million km or about three times the distance between Earth and the Moon.
The video below from the Solar Dynamics Observatory shows the filament intact at first, and then later, from 13:00 to 16:00 UT on November 14, 2011, the filament shoots up from the Sun’s surface and snaps apart.
The SDO team explains that the red-glowing looped material is plasma, a hot gas comprised of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the Sun’s internal dynamo. An erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma.
Despite all this activity, there hasn’t been much as far as solar flares, but Spaceweather.com encourages anyone with solar telescopes to monitor developments.
The Sun captured by NASA's Solar Dynamics Observatory Spacecraft.
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The Solar Dynamics Observatory takes images of the Sun about every 10 seconds, so it easily was able to capture the Sun when the clocks and calendars lined up for a mathematically synchronous readout. Below is another image at the same time in different wavelength.
You can check out what the Sun looks like at anytime of the day or year the the SDO website.
The Sun at 11:11 UTC on 11/11/11 in a different wavelength. Credit: NASA
The Sun looks like a harmless burning ball of fire in the sky: warm, life-giving and forever unchanging. But we know better, don’t we. It’s really a massive ball of churning hydrogen plasma, encased in twisting magnetic field lines, speckled with sunspots, and constantly disgorging vast plumes of radiation and charged particles. The Sun is very active indeed.
The full face of the Sun as seen on Nov. 6, 2011, showing AR 1339 and several other sunspots. Credit: Alan Friedman. Click for a stunning larger version.
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What has been billed as the largest sunspot observed in several years has now rotated around to stare straight at Earth. How large is it? Active Region 1339 and the group of sunspots adjacent to it extends more than 100,000 km from end to end and each of the several dark cores is larger than Earth. The now very active Sun has already blasted out several medium- to large-sized solar flares and has the potential to hurl out more.
And the Sun is now dotted with several smaller sunspots as well. Above is an amazing image of all this activity, as captured by astrophotographer Alan Friedman. “This has been a glorious week for solar observers!” Friedman said. “Led by large sunspot region AR1339, the sun’s disk is alive with activity… the most dynamic show in many years.”
Take a look below for an incredible closeup of AR1339 taken by Friedman, as well as a movie from the Solar Dynamics Observatory showing the sunspots rotating into view.
From all this activity, there may be a good chance for viewing aurorae. On November 9 at around 1330 UT, a magnetic filament in the vicinity of sunspot complex 1342-1343 erupted, producing a M1-class solar flare and hurling a CME into space, which will probably deliver a glancing blow to Earth’s magnetic field on Nov 11 or 12, according to SpaceWeather.com
A portrait of Active Region 1339 in the wavelength of hydrogen alpha light showing the large sunspot group and the maelstrom of chromosphere that surrounds it. Credit Alan Friedman
And here’s an image from astrophotographer Raymond Gilchrist showing a labeled version of all the current sunspots: 1338, 1339, 1340, 1341, 1342, 1343, 1344.
The 'spotty' Sun on Nov. 10, 2011. Credit: Raymond Gilchrist. Click for version on Flickr.
Raymond used a Baader Solar Continuum Filter and Thousand Oaks Full Solar Filter with a Skywatcher 120mm S/T Refractor,
with a Canon 350D, 1/15th Sec Exp. at ISO400. You can see more of his images at his Flickr page.
The Sun as of 20:00 UT on Nov. 3, 2011. AR 1339 is on the northwest limb. Credit SDO/GSFC
One of the largest sunspots in years is now visible, rotating around into view on the Sun’s limb on November 3, 2011. And it’s a feisty one, too. The Solar Dynamics Observatory team called Active Region 1339 a “Bad Boy,” as at 20:27 UTC, a solar flare peaked at X1.9. X-class flares are massive, and can be major events that can trigger planet-wide radio blackouts and long-lasting radiation storms. This region is not facing Earth — yet. But we’ll be keeping on eye on it as it turns toward an Earth-facing direction.
See a full-Sun image from SDO below.
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This sunspot is huge, measuring some 40,000 km wide and at over 80,000 in length. Spaceweather.com said two or three of the sunspot’s dark cores are wider than Earth itself.
Crepuscular Rays seen from the space station on Oct. 18, 2011. Credit: NASA
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Seeing crepuscular rays on Earth is a somewhat rare event, as conditions have to be just right at either sunset or sunrise for the Sun’s rays to appear as though they are diverging outward from the Sun. But seeing them from space is even more rare.
This picture taken by an astronaut on the International Space Station provides an unusual viewing perspective from above of crepuscular rays. Why are they parallel in this picture instead of radiating in an outward fashion like they appear to us on Earth? This image shows the true nature of crepuscular rays: they really are parallel!
The word crepuscular means “relating to twilight,” and they occur when objects such as mountain peaks or clouds partially shadow the Sun’s rays, when the Sun is low on the horizon. These rays are visible only when the atmosphere contains enough haze or dust particles so that sunlight in unshadowed areas can be scattered toward the observer.
The light rays are actually parallel, but appear to converge to the Sun due to “perspective,” the same visual effect that makes parallel railroad tracks appear to converge in the distance.
In the images taken from the ISS, the sun was setting to the west (image left) on the Indian subcontinent, and cumulonimbus cloud towers provided the shadowing obstructions. The rays are being projected onto a layer of haze below the clouds.
Here’s an image taken by UT reader Stephano De Rosa of crepuscular rays as seen from a more Earthly perspective:
Crepuscular Rays. Credit: Stefano De Rosa
Sources: NASA Earth Observatory, University of Illinois
