soho Archives

April 9, 2012April 26, 2016 by Jason Major

Navy Scientists Spot New Solar Structures

A cluster of coronal cells seen by SDO on June 17, 2011. (NASA/SDO AIA instrument)

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There’s something new under the Sun… well, just above the Sun, actually. Scientists at the Naval Research Laboratory have spotted structures in the Sun’s super-hot corona that may shed some light on the way its magnetic fields evolve — especially near the edges of vast, wind-spewing coronal holes.

Coronal holes are regions where the Sun’s magnetic field doesn’t loop back down but rather streams outward into space. Appearing dark in images captured in ultraviolet wavelengths, these holes in the corona allow solar material to flow directly out into the solar system, in many cases doubling the normal rate of the solar wind.

Recently witnessed by NRL researchers using NASA’s SDO and STEREO solar-observing spacecraft, features called coronal cells exist at the boundaries of coronal holes and may be closely associated with their formation and behavior.

The coronal cells are plumes of magnetic activity that stream upward from the Sun, occurring in clusters. Likened to “candles on a birthday cake”, the incredibly hot (1 million K) plumes extend outwards, punching though the lower corona.

Seen near the center of the Sun’s disk, the cells appear structurally similar to granules — short-lived areas of rising and falling solar material on the Sun’s photosphere — but seen from an angle via STEREO, the cells were witnessed to be much larger, elongated and extending higher into the Sun’s atmosphere. For comparison, granules are typically about 1,000 km in diameter while the coronal cells have been measured at 30,000 km across.

“We think the coronal cells look like flames shooting up, like candles on a birthday cake,” said Neil Sheeley, a solar scientist at the Naval Research Laboratory in Washington, D.C. “When you see them from the side, they look like flames. When you look at them straight down they look like cells. And we had a great way of checking this out, because we could look at them from the top and from the side at the same time using observations from SDO, STEREO-A, and STEREO-B.”

Watch a video below of cells made from images acquired by STEREO-B… note how their elongated structure becomes evident as the cells rotate closer to the Sun’s limb.

NRL researchers also noted that the coronal cells appeared when adjacent coronal holes closed and disappeared when the holes opened, suggesting that the holes and cells share the same magnetic structure. In addition, the coronal cells were seen to disappear when a solar filament would erupt nearby, being “extinguished” as the cooler strand of solar material moved across them. Once the filament passed, the cells reformed — again, indicating a direct magnetic association.

The coronal cells were also identified in earlier images from ESA and NASA’s SOHO and Japan’s Hinode spacecraft.

It’s hoped that further study of these candle-like structures will lead to more knowledge of our star’s complex magnetic field and the effects it has on space weather and geomagnetic activity experienced here on Earth.

Read the press release from the Naval Research Laboratory here, and on NASA’s STEREO site here.

March 16, 2012January 24, 2021 by Jason Major

So Long, SWAN…

Remember that newly-discovered comet we mentioned a couple of days ago? Well, it’s gone. Poof. Into the Sun and never to return, it was a sungrazer’s final voyage.

The video above features images from the SOHO spacecraft and description from Bad Astronomer Phil Plait, with music by Kevin MacLeod.

Alas, poor SWAN… at least we knew him.

Read more about the history of Comet SWAN on the Sungrazing Comets site. Video credit: NASA/SOHO (and thanks to Phil Plait for the assembly.)

March 15, 2012April 26, 2016 by Nancy Atkinson

What Does a Solar Storm Sound Like?

Of course, there is no sound in space, but sonfication is a process where any kind of non-auditory data is translated as sound. “We’re transforming space data into the sonic realm such that we can gain a new perspective, and begin to ask new questions,” said Robert Alexander, a doctoral student at the University of Michigan, getting his Ph.D in Design Science, who created this great sonification video of the recent solar storm activity. Alexander used data from two spacecraft: SOHO, studying the Sun, and the MESSENGER spacecraft at Mercury, which has the University of Michigan’s Fast Imaging Plasma Spectrometer (FIPS) on board, an imaging mass spectrometer.

Mercury was recently bombarded with a solar storm, and the sound created from particles colliding with the FIPS is utterly horrifying, sounding like the worst monster you could ever imagine.
Continue reading “What Does a Solar Storm Sound Like?”

March 14, 2012December 23, 2015 by Jason Major

A New Comet’s SWAN Dive Into the Sun

SOHO animation of the latest sun-diving comet (LASCO/NRL SOHO team)

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A new comet has been discovered by the SOHO team, and it — like Lovejoy before it, almost three months to the day — is headed directly toward the Sun. Discovered by SOHO’s SWAN instrument, the comet has been dubbed Comet SWAN… making this a real swan dive (or, perhaps more appropriately, its swan song.)

The animation above has a lot of random noise in it from recent solar outbursts… can you spot the comet? If not, read on…

swanfinder_strip — Labeled frame of the LASCO image (courtesy of SpaceWeather.com)

There’s Comet SWAN, just above the darker silhouette of the bar that holds the shielding disk over the center of the imager (which blocks the glare from the Sun itself.)

The comet is likely another member of the Kreutz family of comets, an extended family of pieces that broke off a larger comet several hundred years ago (which itself may have been a survivor of a breakup in 371 B.C.!) Comet Lovejoy was also a Kretuz sungrazer but it was considerably larger and brighter, which may have helped it survive its Dec. 15 solar close encounter to re-emerge on the opposite side, surprising astronomers everywhere!

Read how some scientists think Comet Lovejoy held itself together.

SWAN may not be so lucky… but then again, we’ve been surprised before!

The comet will make perihelion — its closest approach to the Sun — on March 14. Stay tuned for more details!

Images via SpaceWeather.com.

December 16, 2011December 24, 2015 by Nancy Atkinson

Feisty Comet Lovejoy Survives Close Encounter with the Sun

An image received on Dec. 16th from the Solar and Heliospheric Observatory confirm that Comet Lovejoy survived perihelion and is now receding from the Sun. Credit: NASA, notations by Karl Battams.

It’s the morning after for the sungrazing Comet Lovejoy, and this feisty comet has scientists shaking their heads in disbelief. “I don’t know where to begin,” wrote Karl Battams, from the Naval Research Laboratory, who curates the Sun-grazing comets webpage. “What an extraordinary 24hrs! I suppose the first thing to say is this: I was wrong. Wrong, wrong, wrong. And I have never been so happy to be wrong!”

Many experts were predicting Comet Lovejoy would not survive perihelion, where it came within about 120,000 km from the Sun. But some extraordinary videos by NASA’s Solar Dynamics Observatory showed the comet entering and then surprisingly exiting the Sun’s atmosphere. Battams said he envisioned that if the comet survived at all, what would be left would be just a very diffuse component that would endure maybe a few hours after its close encounter with the Sun. But somehow it survived, even after enduring the several million-degree solar corona for nearly an hour. However, Comet Lovejoy appears to have lost its tail, as you can see in the image below.

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The comet is now in the view of other spacecraft, which will continue monitoring the object. It will likely grow a “new” tail as outgassing of dust, gas and debris will continue. It is not known yet how much of Comet Lovejoy’s core remains — which was 200 meters in diameter earlier this week — or how long it will continue to stay together after its close brush with the Sun.

But we’ll keep you posted!

See more videos of Lovejoy’s survival below:

December 15, 2011December 24, 2015 by Nancy Atkinson

Watch as Comet Lovejoy Takes a Death-Dive Into the Sun

A comet discovered on Dec. 2, 2011 is now on a near collision course with the Sun, and likely won’t survive such a close encounter. The best part is that you can follow along and watch as it happens! Comet C/2011 W3 Lovejoy will pass behind the sun at around 24:00 UTC (7 pm EST) on Thursday, Dec. 15, 2011 and probably won’t be seen again. In the video above, processed images from the STEREO A spacecraft shows Comet Lovejoy blazing towards the Sun, with the comet’s tail wiggling as it interacts with the solar wind.

The Solar Dynamics Observatory website has a special page where they will be uploading the latest images of the comet as it meets its fiery fate. As Comet Lovejoy moves toward perihelion, the SDO team will point SDO a little to the left of the Sun to try and see the tail of the comet with their instruments. This website will allow you to see those images as quickly as they can download them from the spacecraft.

Science live and in action!

Astronomers and various spacecraft have been keeping an eye on Comet Lovejoy the past few days as this Kreutz-group comet headed towards the Sun. Just today (Thursday) the images from the SOHO spacecraft showed the comet sprouting a bulbous head. This is occurring because the comet is getting so bright, it is overwhelming the detectors on the SOHO satellite. “The photons are ‘bleeding’ out to form that cross-like pattern,” said Dan Pendick on the Geeked On Goddard website.

Pendick also quoted solar scientist Jack Ireland from Goddard, who noted that at times two tails can be seen on the comet. “The thick white tail is primarily dust breaking away from the comet nucleus,” Ireland said, as the Sun’s radiation and solar wind that knocks material off the comet nucleus. But to the left is a tail of charged particles (ions) being deflected to the side by the magnetic field carried by the solar wind.

At its closest approach, Comet Lovejoy will pass just 120,000 km above the solar surface. At that distance, the icy comet is not expected to survive the Sun’s fierce heat. But the comet could actually disintegrate at any moment. Kreutz comets have a tendency to evaporate as they approach, or pass close to the Sun.

If the comet does stay the course and stay visible until it goes around the Sun, we likely won’t be able to see its demise because its closest approach will take place on the far side of the Sun.

But this is a great chance to watch this event as it is about to happen.

“We have here an exceptionally rare opportunity to observe the complete vaporization of a relatively large comet, and we have approximately 18 instruments on five different satellites that are trying to do just that,” wrote Karl Battams, from the Naval Research Laboratory, who curates the Sun-grazing comets webpage, and has been documenting Lovejoy’s journey.

Amateur astronomers have been trying to capture this event as well, with everyone wondering how bright the comet will get. For updates from amateur astronomers, check out the Yahoo Groups comet observers forum.

Comet C/2011 W3 Lovejoy was actually discovered by an amateur, Australian astronomer Terry Lovejoy (hence the comet’s name.) This is the first Kreutz comet found from a ground-based observer since 1970, and it was spotted with a modest 8″ telescope too! You can read Lovejoy’s tale of his discovery here.

On average, new Kreutz-group comets are discovered every few days by spacecraft like SOHO, but from the ground they are much rarer to see and harder to discover.

“This is the first ground-based discovery of a Kreutz-group comet in 40 years, so we really can’t be sure just how bright it will get,” said Battams. “However, I do think that it will be the brightest Kreutz-group comet SOHO has ever seen.”

Comet Lovejoy’s spectacular progress can also be monitored via the web at SOHO’s LASCO instrument page.

For the SDO special webpage, images from SDO take about 30 minutes to move from the spacecraft until they are available on the website. The SOD team plans to off-point the spacecraft at 23:30 UTC (6:30 pm ET) and return to normal solar observing at 12/16 00:30 UTC (7:30 pm ET). Images should start arriving by 24:00 UTC (7 pm EST.)

October 3, 2011January 14, 2016 by Nancy Atkinson

Did a Comet Hit Cause an Explosion on the Sun?

This amazing video from the SOHO mission (Solar and Heliospheric Observatory) shows a sun-diving comet hitting the solar surface on October 1, 2011 and unexpectedly a huge explosion occurs shortly after. Are the two events related? Probably not, but solar scientists don’t know for sure. The region where the CME originated was on the opposite side of the Sun from the comet hit, so that is very great distance. Scientists say there is no known mechanism for comets to trigger a CME.

SpaceWeather.com reports that before 2011 most solar physicists would have discounted these two events as being related, but earlier this year, the Solar Dynamics Observatory (SDO) watched another sungrazer comet disintegrate in the Sun’s atmosphere, and it appeared to interact with plasma and magnetic fields in its surroundings as it fell apart. Could a puny comet cause a magnetic instability that might propagate and blossom into a impressive CME? Most likely this is just a coincidence, but this is definitely an event in which solar scientists are taking a closer look. The comet, named SOHO-2143, was just discovered on Sept. 30 by an amateur astronomer.

See below for SDO’s look at two solar flares which also occurred on October 1, showing how events on the Sun can be related.
Continue reading “Did a Comet Hit Cause an Explosion on the Sun?”

August 23, 2011December 24, 2015 by Tammy Plotner

Scientists Detect Sunspots Before They Emerge

Stanford researchers have found a way to detect sunspots such as these two days before they reach the surface of the Sun. Image Credit: Thomas Hartlep

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For solar enthusiasts, we’re all quite aware of sunspots and their implications. Able to disrupt power grids, shut down satellite communications and pose hazards to astronauts, these “cool” customers are revealing themselves ahead of their surface appearance. Thanks to the Michelson Doppler Imager aboard NASA’s Solar and Heliospheric Observatory satellite, known as SOHO, researchers were able to take 15 years of “sound” data from our nearest star… and develop a new technique for detecting sunspots before they emerge.

By combining information with NASA’s Solar Dynamics Observatory satellite, which carries the Helioseismic and Magnetic Imager, scientists have discovered a new method for detecting sunspots as deep as 65,000 kilometers below the solar surface. The areas of intense magnetic fields produce acoustic waves from the turbulence of plasma and gases. Near the surface, a convection cell echoes the information which travels back to the solar interior – only to be refracted again. By comparing their findings to seismic waves studied here on Earth, researchers measure the waves between points to predict anomalies.

Detection of Emerging Sunspot Regions – 18 August 2011: Movie showing the detected travel-time perturbations before the emergence of active region 10488 in the photosphere. The first 10 seconds of the movie show intensity observations of the Sun. The intensity later fades out and the photospheric magnetic field is shown. In the next 20 seconds, we zoom in to a region where a sunspot group would emerge. The upper layer shows magnetic field observations at the surface and the lower layer shows simultaneous travel-time perturbations, detected at a depth of about 60,000 km. After the emergence, intensity observations show the full development of this active region, until it rotates out of view on the west solar limb. (movie made by Thomas Hartlep) Courtesy of the Helioseismic and Magnetic Imager.

“We know enough about the structure of the Sun that we can predict the travel path and travel time of an acoustic wave as it propagates through the interior of the Sun,” said Junwei Zhao, a senior research scientist at Stanford’s Hansen Experimental Physics Lab. “Travel times get perturbed if there are magnetic fields located along the wave’s travel path.”

By comparing and measuring millions of pairs and points, researchers are able to pinpoint areas where sunspots are likely to happen. What they have discovered is larger spots rise to the surface faster than smaller ones… a prediction which can be made in approximately 24 hours. For less ominous appearances, lead times increase to up to two days.

“Researchers have suspected for a long time that sunspot regions are generated in the deep solar interior, but until now the emergence of these regions through the convection zone to the surface had gone undetected,” Ilonidis said. “We have now successfully detected them four times and tracked them moving upward at speeds between 1,000 and 2,000 kilometers per hour.”

The ultimate goal is to improve space weather forecasting. If events can be predicted three days prior, advance notice can be given and proper precautions taken.

Original Story Source: Stanford University News.

June 21, 2011December 24, 2015 by Nancy Atkinson

Sun Celebrates Solstice With Flare (and a CME)

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.