Spectacular Photos from the Jan. 4 Partial Solar Eclipse

Amazing Swedish view of Jan 4, 2011 partial solar eclipse, which reached its maximum – about 85%- in this stunner from Stockholm, Sweden. Poor weather and obscuring clouds momentarily relented at just the perfect time. Credit: Peter Rosen


Millions across Earth enjoyed one of nature’s most awesomely spectacular events during today’s (Jan. 4) partial solar eclipse – the first of four set to occur in 2011. And there was nothing partial about it, for those lucky eyewitnesses where it was visible in parts of Europe, Africa and Central Asia. The eclipse reached its maximum, about 85%, in Sweden. See the maximum stunner above – taken despite pessimistic weather forecasts -by Peter Rosen in Stockholm, Sweden, with more photos from the sequence here at spaceweather.com

Probably the most technically amazing feat is the double solar eclipse captured in one image by renowned astrophotographer Theirry Legault – see below – boasting both the ISS and the Moon on the eclipsed sun’s face. Legault had traveled to the deserts of the Sultanate of Oman, near to the capital of Muscat, for this rare spectacle of nature. The ISS was calculated to be visible in a thin strip barely 11 kilometers wide, according to Astronomie Info news. The ISS transit lasted just about 1 second, speeding by at 28,000 km/sec.

See a global compilation of gorgeous eclipse photos here and comment or send us more.
Update 1/6/11: this is a work in progress so please check back again.
New readers photos and eyewitness accounts added below today; as received

Click to enlarge all photos
First up: Double Solar Eclipse by renowned astrophotographer Theirry Legault in Oman

Amazing Double Solar Eclipse with the ISS and the Moon captured in one image in the deserts of the Sultanate of Oman. Credit: Theirry Legault

Check out this exciting gallery of images contributed by eclipse watchers from multiple locations around the world, on Flickr

Composition of 8 different exposures between 8.10 and 9.18 (local) recorded with solar filter and added to a unfiltered picture at the beginning of sequence. Taken with a Sony DSCW-1 with 35mm equivalent focal length. Credit: Marco Di Lorenzo, Pescara, Italy

Here is a collection of images and an eyewitness report sent to me by Marco Di Lorenzo, in Pescara, Italy

Filtered and unfiltered views at 9.11 local time. Credit: Marco Di Lorenzo

Marco writes; Pescara is located at 42.467°N and 14.225°E, about in the center of Italy on the Adriatic sea. I chose my location at the new pedestrian bridge because it is a modern structure which offers a nice foreground and also an open, elevated viewpoint. I used a couple of cameras plus a digital video camera. All the cameras were mounted on a tripod.

The weather was cold and the situation didn’t improve in the mid morning. Illumination was comparable to a slightly foggy day. The frigid temperature didn’t encourage people to go out and check. However some people did venture out. Someone asked me some info on eclipses and how to take pictures of it – very hard indeed, especially if you use a cellular phone !

Combo of 2 pictures taken few seconds apart using solar filter and different exposure; local time was 9.11 AM, near maximum. Marco Di Lorenzo

Urijian Poernick sent these photos and description:
“Colorful Solar Eclipse” at Halley Astronomical Observatory, Heesch, The Netherlands

Partial Solar eclipse and flock of birds from Heesch, The Netherlands. Credit: Urijian Poernick

The weather forecast predicted overcast skies with only a few small bright intervals in all parts of The Netherlands. Nevertheless, dozens of members of Halley Astronomical Society and visitors, including many children, challenged the cold winter weather and came together on the flat roof of Halley Astronomical Observatory in The Netherlands.

Partial Solar eclipse from Heesch, The Netherlands. Credit: Urijian Poernick
After sunrise at 7:44 UT (8:44 local time) they all looked at a narrow opening in the cloud deck near the eastern horizon. At 8:00 UT the sun showed itself: first we saw the left horn of the eclipse and a few moments later the right one.

Due to the clouds and veils it was a very colorful eclipse, with all tints of red and yellow. After twenty minutes the sun and the moon disappeared behind the overcast skies again and they didn’t come back before the end of the eclipse (9:39 UT).
During this short period everyone could watch the eclipse through the telescope and we were all enthusiastic. It was a beautiful spectacle! www.sterrenwachthalley.nl

Gianluca Masi is the National Coordinator of Astronomers Without Borders in Italy and captured this pair of photos from partially overcast Rome, Italy. The clouds contributed to make for a delightfully smoky eclipsed sun

Smoky eclipsed sun from Rome, Italy. Credit: Gianluca Masi

Credit: Gianluca Masi

Edwin van Schijndel sent me this report from the Netherlands:

I made some pictures in the southwest of the Netherlands. The weather conditions were not so good in the early morning, most places were covered by clouds so we decided to move about 70 miles to the southwest from our hometown. Finally we stopped not far from the city of Bergen op Zoom and were able to see sunrise while most of the sun was covered. It was splendid!

Eclipsed sunrise from Bergen op Zoom, the Netherlands. Credit: Edwin van Schijndel

Unfortunately there came more clouds so the rising sun disappeared and we drove 20 miles to the north just before Rotterdam and the sky was more clear at this place. Again we took some pictures but the maximum covering of the sun had been a few minutes before. After all this wasn’t really a pity, we were very lucky to have seen the rising of the sun and be able to make some nice pictures of the partial eclipse. Many people in the Netherlands saw less or even nothing.

Credit: Edwin van Schijndel

Credit: Edwin van Schijndel

Send us or comment more solar eclipse photos to post here. ken : [kremerken at yahoo.com]

Look here for some photos from the recent total lunar eclipse on Dec. 21, 2010

Read a great preview about the eclipse by Tammy Plotner

More Readers Photos and Eyewitness Accounts. Beautiful, Thanks ! ken

Story and Photos sent me by Stefano De Rosa. Turin, Italy

Early in the morning, I moved to a site close to Turin (Italy) where the forecast was not so bad as in my city to try to observe and photograph the partial solar eclipse. Unfortunately, when I arrived it was cloudy and foggy and so decided to go back home. Technical details: Canon Eos 1000d, F/22; 150-500mm lens @ 500mm; ISO. 1/1600 sec

Turin, Italy. Credit: Stefano De Rosa

Suddenly, as I was sadly driving on the motorway, close to the city of Alessandria, noticed a little break on the clouds from my rearview mirror: I stopped the car and, after a quick set up, managed to capture the crescent Sun!
Well, I hope you carefully looked back before hitting the brakes ! – ken
Turin, Italy. Credit: Stefano De Rosa


Story and Photos sent me by Roy Keeris, Zeist, The Netherlands

Middelkerke, The Netherlands. Credit: Roy Keeris

Me and a friend (Casper ter Kuile) wanted to see the eclipse from The Netherlands. If clouds should intervene, we planned to drive a little (max. a couple of hours) to a place with a better chance for a clear sky. During the night we checked weather forecasts and satellite images. We were pretty unsure if we would succeed in seeing the eclipse, because it was pretty cloudy, and especially the low clouds tend to be quite unpredictable. In the end we chose to drive to Middelkerke (near Oostende) in Belgium because of a clear spot approaching from the North Sea.

Middelkerke, The Netherlands. Credit: Roy Keeris

We arrived at the Belgian coast just in time before sunrise. There we witnessed the eclipse from the top of a dune. About 25 minutes after sunrise the sun appeared from behind the lower clouds, just when the eclipse was at its maximum. It was magical!
First we saw the right ‘horn’ and then the left one appeared. From then on we watched the rest of the eclipse and took many pictures. [no pics from Casper ??]

Later we heard that despite the clouds, many people in The Netherlands were able to see the eclipse. There was a long stretch with a clear zone in the clouds- near the border of Germany.

Middelkerke, The Netherlands. Credit: Roy Keeris

If they had a clear horizon, people could look underneath the clouds and were just able to see the sunrise. I could even have seen it at home from my apartment on the 13th floor! But the trip was fun. It’s always nice to hunt for the right place to be at these events.

Here are some pictures I took from Middelkerke. They were shot with a Canon 400D in combination with a Meade ETS-70 telescope and a Tamron 20-200mm lens.

Thanks – Yes the hunt is half the fun. ken


Story and Photos sent me by Igal Pat-El, Director, Givatayim Observatory, Tel Aviv, Israel

We took some images of the Jan. 4 Solar Eclipse from the Givatayim Observatory, just near Tel-Aviv, Israel. We were pleased to have Prof. Jay Passachoff as a guest during the eclipse. We had a live broadcast in plan but we had to cancel it due to heavy rain from the first contact, therefore we closed the dome’s shutter and went to the balcony trying to take some quick photos of the eclipse.

Tel Aviv, Israel. All Photos Credit: Igal Pat-El, Givatayim Observatory.
Collage assembled by Ken Kremer

We had the portable PST Coronado CaK telescope with a Ca filter On a Alt-Az mount (we could not do any alignment due to the rain). We took about 5 images against all odds in this very dim filter, using the Orion SS II Planetary imager, all of them through the haze and clouds.

Thanks, Igal. Another good lesson learned. Take a chance. You never know what you’ll get till you try !
I’ve combined Igal’s photos into a collage for an enhanced view. ken

See more photos and a video in comments section below

Upcoming Solar Eclipse on January 4, 2011

Williams astronomer Jay Pasachoff during the partial phase of the March 29, 2006 solar eclipse. Photo by Anna Tsykalova.


Some of the world will be able to greet the first part of the new year with a solar eclipse. On the morning of Tuesday, January 4, 2011, an eclipse of the Sun will be widely visible across Europe and as far east as India. The eclipse won’t be visible in North and South America, however. Jay Pasachoff of Williams College in the US is the Chair of the International Astronomical Union’s Working Group on Eclipses, and says that even at a maximum, this eclipse will be only partial, with some of the Sun always visible. Because the Sun is too bright to look at safely, Pasachoff stresses that special solar filters or projection methods should always be used to protect the eyes.

Pasachoff will be in Tel Aviv to view the eclipse, and since partial eclipses are usually not very scientifically useful, he is looking forward to just enjoying the eclipse instead of scrambling to set up various scientific equipment.

“Partial eclipses are fun, and much more relaxing for a total-eclipse scientist like me, since the pressure on me is low and nothing happens too fast,” he told Universe Today. “Seeing a partial or other solar eclipse happen right on time, to the second, can be inspirational to students to study hard so that they, too, can understand the Universe.”

This will be Pasachoff’s 52nd solar eclipse.

Radio astronomers do find partial eclipses useful, as with a radio telescope, or in the ultraviolet or x-rays from spacecraft, scientists can use the timing of when solar active regions are covered and uncovered to study the structure of solar storms in better detail than is otherwise possible, Pasachoff said.

For this eclipse, people in Western Europe will find the Sun already eclipsed as the day begins, with the eclipse lasting about 80 minutes more. On January 4, the Moon will gradually cover the Sun, over a period of about 3 hours. At maximum, the eclipse will be at the horizon at sunrise in England, with 75% of the Sun’s diameter covered, and then gradually emerge over the next hour and 20 minutes. In Paris or Berlin, 80% of the Sun will be covered near sunrise. Farther east, the Sun will be a bit higher in the sky at maximum, 22° high with 67% covered in Athens. In Israel and Egypt, the Sun will be 33° high with over 55% coverage at maximum.

The most important thing, Pasachoff said, is to view an eclipse safely.

“Whenever the ordinary Sun is visible, even only part of it, you should not stare at it,” he said. “Special solar filters are available cheaply, or dense welders’ glass will do. Another method of seeing that the Sun is eclipsed is to punch a hole a few millimeters across in a piece of cardboard and hold it up to the Sun while you face away from the Sun and see the Sun’s image projected on the ground or onto another piece of cardboard. This method is called projection with a pinhole camera. It is rare that haze or clouds are sufficient to reduce the Sun’s intensity enough that one can see a partially covered Sun safely.”

2011 is unusual in that it has only four partial solar eclipses, for all of which the darkest part of the Moon’s shadow passes off the Earth’s surface. In 2012, an annular eclipse in which the Moon’s disk is a little too small to cover the entire Sun will pass from Japan over the Pacific to California and farther into the U.S. on May 20. On November 14, 2012, a total solar eclipse, in which it becomes dark as twilight, will start in northeastern Australia and cross a broad swath of the South Pacific.

For further information:

The International Astronomical Union’s website about eclipses with information on how to view an eclipse safely and why solar eclipses are interesting.

NASA’s website from Fred Espenak with maps, and tables for cities around the world.

Israel Astronomy Society at Givatayim Observatory

University of Barcelona’s Department of Astronomy and Meteorology.

Bareket Observatory, a private observatory in Israel.

July 11 Total Eclipse Among the Mysterious Moai

The Moai statues on Easter Island.


A group of astronomers are now on the mysterious Easter Island, one of the few solid places to stand on Earth where a total solar eclipse will be visible on July 11, 2010. The majority of the eclipse’s path is over the ocean, so this will be one of the least observed eclipses ever. “This is one of the most interesting things that is possible for anyone on Earth to see in one of the most interesting places on the Earth that people can go,” said Jay Pasachoff from Williams College, who is the Chair of the International Astronomical Union’s Working Group on Eclipses. This will be his 51st eclipse.

Williams astronomer Jay Pasachoff during the partial phase of the March 29, 2006 solar eclipse. Photo by Anna Tsykalova.

While the eclipse is thousands of miles long in its is path of totality on Earth, it is just a few hundred miles wide. It will pass through French Polynesia on the Cook Islands, but, Pasachoff said, it doesn’t go through any of the main islands. “It misses Tahiti, but there are some atolls off the side of the path, and some eclipse scientists and ecotourists will be on cruise ships that are going into the path of totality. There will also be a group on an airplane observing the eclipse and we hope to compare all the other observations with the ones we get from Easter Island,” he said.

Easter Island is 4023 km (2,500 miles) west of Chile, and is famous for the Moai, giant statutes that were left by a Polynesian culture that mysteriously disappeared. But while the statues’ constant gaze look outward, all human eyes will be on the skies on July 11.

“The actual four minutes and forty-five seconds of totality that we are scheduled to have at Easter Island will be very exciting, as the last sliver of the sun is covered we can then take off the protective filters we’ve been using,” Pasachoff said, “and look at the next few minutes without any protection because the solar corona is about the same brightness as the full moon and is equally safe to look at. In fact we’ve been having a debate recently about whether we can get a very brief warning on the so-called eclipse glasses that many people use because those glasses are only for when any of the everyday sun is visible. They are so dense that they block the solar corona entirely, and the few people who don’t understand what is going on enough to take those glasses off during totality miss the whole event. There are people who have missed past eclipses by not knowing they had to take their glasses off.”

Pasachoff is joined by Professor Marek Demianski and two students. They will be carrying out high-resolution imaging to look for motions in the corona and to follow the varying magnetic-field configuration in the solar-corona as a function of the solar-activity cycle. Though the sunspot cycle remains in an extreme low, some other indications of solar activity have been increasing and we are eager to see the condition of the low and middle corona. They expect to see motions at least in polar plumes.

Also, they will be using the images to fill in gaps between the observations of the corona on the solar disk taken with NASA’s new Solar Dynamics Observatory and the observations of the outer corona taken with the Naval Research Laboratory’s coronagraph on the Solar and Heliospheric Observatory. Pasachoff and his team have contributed to similar images for the past several eclipses but now will have the improved SDO images as part of their montage. Several of the cameras will be computer controlled using software called Solar Eclipse Maestro written by Xavier Jubier of France.

Universe Today hopes to talk with Pasachoff after the eclipse to hear about his experiences.

The Williams College team is accompanied by a documentary crew filming for National Geographic Channel, and their activities will be covered in a special program entitled Easter Island Eclipse partly pre-recorded and partly expected to have new eclipse footage that will air on the National Geographic Channel on the evening of July 11th, at 11 pm.

Here are some resource Pasachoff provided for the eclipse:

On Sunday, July 11th: total solar eclipse on Easter Island (same time zone as Mountain Time in the US)
Partial eclipse begins 12:40:36 Altitude of Sun: 40°
Totality begins 14:08:30 Altitude of Sun: 40°
Totality ends 14:13:10 Altitude of Sun: 39°
Partial eclipse ends 15:34:16 Altitude of Sun: 32°
Duration of totality: 4 minutes and 40 seconds

Times in UT:
18:40 UT 1st contact
20:08 UT 2nd contact: total eclipse begins
20:13 UT 3rd contact: total eclipse ends

His eclipse site for the International Astronomical Union

Google maps by Xavier Jubier and Fred Espenak

Espenak’s NASA Website, with maps and details

An interactive map

An animation of eclipse phenomena

Also, Pasachoff will talk about the eclipse on the July 10 365 Days of Astronomy podcast.

Here’s a link to USTREAM channel of the eclipse.

Update: I just received a note from Robin Zimmerman at DISH Network, and for those of you who have the DISH Network, there is a special channel, DishEARTH, Ch. 287, that features live 24/7 views of the earth from space and this Sunday the eclipse be shown. Robin said their network will allow people in the US to see the phenomena, live.

And here’s a video from National Geographic:

Satellite Captures Solar Eclipse from Space

Solar eclipse seen by Proba-2's SWAP instrument. Credit: ESA

The recently launched Proba-2 satellite was able to observe the annular solar eclipse on January 15, 2010, with stunning results. The PRoject for OnBoard Autonomy satellite was launched on November 2, 2009 and is intended to test hardware and software that might be incorporated into future ESA missions. The eclipse offered a unique chance to test out the Sun-imaging instrument, SWAP (Sun Watcher using APS detectors and imaging processing). Another radiometer instrument was also able to take measurements during the eclipse.

Proba-2 is one of the smallest satellites launched. The 0.6m by 0.6m by 0.8m satellite contains several instruments, a computer, battery, thrusters, and solar panel systems.

The eclipse was also detected by the Proba-2's LYRA (Lyman Alpha Radiometer) instrument. Credit: ESA

The eclipse was also detected by the Proba-2’s LYRA (Lyman Alpha Radiometer) instrument, the first ultraviolet radiometer in space that employs diamond detectors. LYRA will measure solar flares with an unprecedented rapid time resolution of 0.5 sec. LYRA data will soon be feeding research investigations and space weather forecasts.

Proba-2 was a secondary payload included on the launch of the SMOS mission, the Soil Moisture and Ocean Salinity Earth Explorer.

Source: ESA

Annular Eclipse Photos, Videos From Earth and Space

Caption: Annular solar eclipse on January 15, 2009. Courtesy Daniel Fischer, “cosmos4u” on Twitter.

The first of two solar eclipses to occur in 2010 took place Friday, January 15. This was an annular eclipse, which means the Sun was not totally covered by the Moon, creating a “ring of fire.” The eclipse was visible from a 300-km-wide track that passed over central Africa, across the Indian Ocean, over the southern tip of India and the northern end of Sri Lanka, and then across parts of Bangladesh and Myanmar. At the center of the track, the eclipse endured for 11 minutes and eight seconds, setting a record that won’t be beaten until December 23, 3043. Weather cooperated in many regions, allowing good viewing conditions. Here are a few images and videos from Daniel Fischer, who was in Varkala, India, and another group who calls themselves Eclipse Hunt 2010 crew were in Jaffna, Sri Lanka. The image above is from Fischer, who said via Twitter that his travels to view the eclipse was a total success. “Deep blue sky, not a single cloud all day, photo plans worked.”

Annular eclipse, Jan 15, 2010 by Shehal Joseph and Romayne Anthony. Courtesy Elipse Hunt 2010 website

This image is from the Eclipse Hunt 2010 crew, in northern Sri Lanka. It was taken by Shehal Joseph and Romayne Anthony. They used a Celestron NexStar 5se telescope with a focal length of 1.25m, and an energy rejection filter.

Why the “ring of fire?” During an annular eclipse, the moon is a little further than average away from the earth and its angular size in the sky is therefore slightly smaller than the angular size of the sun. So it is like the Moon is silhouetted against the Sun, and it doesn’t cover the Sun entirely. A a ring, or annulus, of sunlight can be seen around the black disk of the moon.

The Moon casts a shadow on Earth, as seen by NASA's Aqua satellite from space. Credit: NASA

NASA’s Aqua satellite was looking down from space at 1:15 p.m. Calcutta time (7:45 UTC) on January 15, 2010, and saw the Moon’s shadow cast on Earth. The Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua images this shadowed area in India and the Bay of Bengal. The shadow spanned a north-south distance of about 300 kilometers (185 miles) on the surface, with the darkest part near the mid-point of the span.

The Sun's chromosphere was visible in a long exposure. Credit: T. Kampschulte

This is another image from the Fischer’s group of astrophotographers in India. By taking a long-exposure image, the sun’s chromosphere was able to be seen.

Normally with an annular eclipse, not a lot of science is able to be done, said Jay Pasachoff, who leads the IAU’s working group on eclipses. “Because it doesn’t get completely dark, we won’t be able to see the solar corona, the diamond ring, or the fantastically interesting and beautiful phenomena that one sees at a total solar eclipse, but still annular eclipses are interesting to see,” Pasachoff said on the 365 Days of Astronomy podcast. “You have to keep a solar filter on to look through for the whole time. The partial phases that last an hour and a half and the annular phase, which, for this eclipse, lasts, in many places, over ten minutes – very long for an eclipse.”

Interestingly, the images shown here by Fischer’s group used a very low-tech combination of a compact camera and their filters were two “rescue sheets,” the thin aluminum foil-like thermal blankets usually given out during emergency situations, such as the recent earthquake in Haiti.

The Eclipse Hunt 2010 crew took a few videos of the eclipse, using the projection method. See more of their videos here at their You Tube page. And see more images on their website, Eclipse 2010. Special thanks to Prasanna Deshapriya, one of the members of the Eclipse Hunt 2010 crew, who shared these images. Check out his website about the IYA in Sri Lanka.

A high resolution image from a telescope in India. Credit: T. Kampschulte

This high-resolution image obtained using a telescope was taken by Fischer’s group in India. “The Ring of Fire is closed, but just barely; it measures a few arc seconds only in places in this super-sharp telescopic image,” said Fischer, via Twitter.

For more eclipse images go to:

Spaceweather.com’s eclipse gallery

Flickr’s eclipse thread

More eclipse videos on You Tube

More links to the eclipse can be found here.

Plus, the Jan. 18 Astronomy Picture of the day is from the eclipse.

The next solar eclipse will be a total eclipse, on July 11th, 2010. “That won’t be seen by very many people at all,” said Pasachoff. “It is largely over the Pacific Ocean, where it will cross some normally uninhabited atolls not far from Tahiti, so there’ll be some ships there and some few expeditions out of Tahiti to see that. The major land in the way is a very unusual island, Easter Island. It’s in the middle of the Pacific, some 4,000 miles west of the coast of Chile.”

But, Pasachoff will be there.

India Launched 11 Rockets to Monitor Eclipse

India launched a small fleet of rockets to monitor the effects of the annular solar eclipse that occurred today. A total of 11 Rohini sounding rockets – suborbital rockets designed for scientific experiments – were launched from several different sites, including the Satish Dhawan Space Centre (SDSC) in Sriharikota. These rockets, launched by the Indian Space Research Organization (ISRO), carried instruments to measure the effect the eclipse had on the Earth’s atmosphere.

The eclipse – which lasted 11 minutes and 8 seconds at its peak, was visible to observers in Africa, southern Asian countries, India and China. This was an annular eclipse, meaning that the Moon blocked the Sun’s light enough for a bright ring to be seen around the silhouette of the Moon, and was the longest such eclipse of the millennium.

There are several phenomena that take place in the lessening of the Sun’s rays during an eclipse. When the solar radiation drops during an eclipse, the ionization that occurs in the atmosphere is temporarily lowered, causing disruptions in the Equatorial Electrojet – a ribbon of electric current that flows east to west near the equator.

The temperature and wind of the atmosphere are also altered by the cessation of sunlight, and were measured by the rockets. India launched five rockets yesterday to record pre-eclipse data, and then six more were launched today to measure the changes after the eclipse, which peaked at 1:15pm local time. Over 90% of the Sun’s light was blocked near the Thumba Equatorial Rocket Launching Station (TERLS), which lies on the southern tip of India, and was well-placed to measure the eclipse.

“Results of these experiments will coordinate ground-based eclipse observations with in situ space measurements. Interpretation of eclipse data together with space data is expected to give new insights to the earlier eclipse observations,” the ISRO wrote in a press release.

Sounding rockets have been used by other space agencies to monitor the ionosphere and the role of the Sun in atmospheric phenomenon. In 1994, NASA cooperated with Brazil on the Guara Campaign, named after the Guara bird that is native to Brazil. In August-October of that year, NASA launched a total of 33 rockets with various experiments to measure the photochemistry and plasma of the atmosphere near the equator. All of the rockets were launched from the Alcantara launch range in Brazil.

Source: ISRO press release

Measuring the Coronal Temperature with Iron

This image of the solar corona contains a color overlay of the emission from highly ionized iron lines and white light taken of the 2008 eclipse. Red indicates iron line Fe XI 789.2 nm, blue represents iron line Fe XIII 1074.7 nm, and green shows iron line Fe XIV 530.3 nm. This is the first such map of the 2-D distribution of coronal electron temperature and ion charge state. Credit: Habbal, et al.

Astronomers presenting at this week’s AAS conference have reported on new research measuring the temperature of the solar corona. The work combines observations of the Sun’s outer reaches from observations during total solar eclipses in 2006, 2008, and 2009. It utilized mapping of various abundances of ionized iron to build a two dimensional temperature map.

Although many introductory science classes paint temperature as a fixed number, in reality, it’s the average of a range of temperatures which is a way of quantifying the kinetic energy of the particles in question. Individual particles may be hotter (higher kinetic energy) while others may be cooler (lower kinetic energy). As these atoms move around, they can collide and these collisions will knock off electrons causing the atoms to become ionized. The degree of ionization will be indicative of just how energetic the collision was.

Those ionized atoms can then be identified spectroscopically or by using a filter to search for the wavelength at which those atoms will emit light as new electrons settle down into the previously vacated orbitals. By measuring the relative amounts of ionization astronomers can then reconstruct the range of kinetic energies in the gas and thus, temperature range which can, in turn, be used to determine the average temperature.

This is the method an international team of astronomers used to study the sun’s corona. Since light atoms don’t work well for this method (they become fully ionized or just can’t show a large range of ionization like atoms with more electrons), the astronomers chose to study the Sun’s corona through various states of iron ionization. In doing so they mapped several ionization states, including capturing for the first time, the elusive Fe IX lines (iron with 8 electrons knocked off) at 789.2 nm.

One interesting finding was that the region of emission extended to three solar radii (or 1.5 times the diameter). After this distance, the collision rate drops off and can no longer cause the ionization of atoms (however, radiative processes caused by photons from the sun can still ionize the atoms, but this is no longer indicative of the temperature of the atoms). This was further than originally anticipated.

Another result of their work showed that there is a strong correspondence between the amounts of various ions coming from the sun and that same ratio in interplanetary space as measured by the SWICS on the Advanced Composition Explorer. This connection will better help astronomers understand the working of our Sun as well as how its emissions may impact the Earth.

The full results of this work are to be published in the January 10 issue of the Astrophysical Journal.