Enhanced Technique for Tracking Solar Storms All the Way From Sun to Earth

Heliophysicists announced today that new data processing techniques have enabled them to track solar storms from their origin in the Sun’s fiery corona all the way to impact with the Earth in unprecedented detail. “For the first time we’ve been able to image a coronal mass ejection all the way through its entire life cycle, from inside the solar corona until it reaches Earth,” said Craig DeForest, speaking at a NASA press briefing. DeForest is the lead author paper published in the Astrophysical Journal.
Continue reading “Enhanced Technique for Tracking Solar Storms All the Way From Sun to Earth”

STEREO Spacecraft Provides First Complete Image of Sun’s Far Side

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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:

Source: PhysOrg

Earths Entire Star for the First Time on Super SUNday

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Super Bowl SUNday XLV marks a watershed moment in observing our Sun. Today, February 6, 2011, NASA’s twin STEREO solar observatories will reach locations on exact opposite sides of the Sun, called opposition, and they are beaming back uninterrupted images from both the entire front and rear side hemispheres of Earths star in three dimensions and 360 degrees for the first time.

“For the first time in history we can see the entire Sun at one time – both the far side and the near side,” said Joe Gurman, in an interview for Universe Today. Gurman is the Project Scientist for NASA’s STEREO mission at the NASA Goddard Spaceflight Center in Greenbelt, MD. This will significant aid space weather forecasting.

To mark this historic milestone, NASA today released images captured by STEREO on Feb. 2 – slightly prior to opposition – which gives humankind our first ever global look at the whole sphere of our Suns surface and atmosphere in extreme ultraviolet light (EUV). The probes were over 179 degrees apart. See location maps and images below

This article features even newer EUV images – compared to NASA’s press release – that were taken even closer to opposition by STEREO on Feb. 3 and today on Feb. 6 and which I downloaded from the STEREO website. The newer EUV images show an ever so slightly more complete solar view as the probes orbit reaches further to the suns far side.

Coincidentally, the STEREO duo may reach opposition – exactly 180 degrees apart – while the Super Bowl XLV half time show is ongoing, at roughly 7:30 p.m. EST in the evening of Sunday, Feb. 6.

The Sun from STEREO A and B on Feb. 3, 2011.
Images taken by the SECCHI Extreme Ultraviolet Imager (EUVI) at the 304 Angstrom bandpass which is sensitive to the He II singly ionized state of helium, at a characteristic temperature of about 80 thousand degrees Kelvin. These are the most current images used to create the spherical solar view on Feb 3, 2011. Credit: NASA

There is a tiny sliver of unseen solar surface on the far side of the sun at the extreme fringes of the far side EUV images that will fill in over the new few days to give an even better view. As of today that wedge is less than 1 degree. See the solar image collections above and below.

“The currently unseen far side wedge will disappear around February 12,” Gurman told me. “There might still be some small areas at high latitudes we won’t be able to see, but the view from the ecliptic is always limited. It takes about 3 days to get back the high resolution data.”

“On either side of the wedge, the features are smeared out because they’re from the “limbs” (edges) of the Sun as seen from each STEREO spacecraft.”

“The far side resolution will increase as the STEREO twins proceed around the sun.”

“On the near side, we can substitute the much higher resolution SDO AIA image data along the nearside “seam”, said Gurman.

SDO is in Earth orbit on the earth-facing side of the sun and will fill in the gap.

“For the next 8 years we will have a 360 degree view of the Sun by combining STEREO and SDO data,” said Gurman. “We will have that whole sun view until the STEREO spacecraft swing back to the earth side of the Sun.”

The Sun from STEREO A and B on Feb. 6, 2011 on SuperSUNday.
The probes were nearly at opposition 180 degrees apart. These images provide the first 360 degree global view of Earths Star. Images taken by the SECCHI Extreme Ultraviolet Imager (EUVI) at the 195 Angstrom bandpass is sensitive to the Fe XII ionization state of iron, at a characteristic temperature of about 1.4 million degrees Kelvin. Credit: NASA

Why is it important to image the far side of the sun?

Because scientists can now immediately detect active regions on the far side of the sun which were hidden from our view up until now.

“No active region can hide from us anymore because we will now have this 360 degree view.”

The new far side data will allow much faster detection of solar storms which in turn will enable faster predictions of space weather which potentially can severely impact sensitive technological infrastructure on Earth and throughout the solar system.


Until now, we had to wait about two weeks until the rear side active regions of the sun rotated into our view on the front side. But no longer. On average the sun rotates in about 27 days – faster at the equator and slower at the poles.

“We will now be able to detect the coronal mass ejections, or CMEs as they happen on the far side instead of waiting until they rotate around with no forewarning. The magnetic storms with energetic particles blast out at varying speeds of about 700 to 1000 km/sec and can reach Earth in one to three days,” said Gurman.

These magnetic storms are a threat to air traffic control of airliners, can disrupt the power grip, damage communications systems, space satellites in Earth orbit and around the solar system, effect other sensitive electronics systems and also harm astronauts working aboard the International Space Station.

An artist's concept shows both STEREO surrounding the sun on opposite sides. Credit: NASA

STEREO is comprised of two nearly identical STEREO spacecraft – dubbed STEREO Ahead and STEREO Behind –orbiting around our Sun. One probe – B – trails Earth around the sun and moves a bit slower; the other one – A – leads the Earth traveling slightly faster.

Each probe images half of the suns sphere and broadcasts the data back to Earth continuously, 24 hours each day. STEREO’s solar telescopes are tuned to four different wavelengths of extreme ultraviolet radiation (171, 195, 284, 304 Å) selected to trace key aspects of solar activity such as flares, tsunamis and magnetic filaments.

“The images are converted into a spherical projection by researchers on the science teams,” said Gurman. An international group of scientific institutions and governments from the U.S., UK, France, Germany, Belgium, Netherlands and Switzerland designed and built STEREO’s science imaging and particle detecting instruments.

The two probes have been slowly separating in opposite directions at about 45 degrees per year ever since they were launched together aboard a Delta II rocket on October 25, 2006 from Cape Canaveral Air Force Station (CCAFS) in Florida.

After hurtling past the moon, the solar powered spacecraft – weighing some 600 kg – were flung into solar orbit on opposite sides of the Earth and have been moving away from Earth and apart from each other. In this way the wedge of unseen solar territory has been diminishing as the probes gain more complete coverage of the sun, thus enabling us to formulate a more complete understanding of the solar environment.

STEREO stands for Solar TErrestrial RElations Observatory. Their mission is to provide the very first, 3-D “stereo” images of the sun to study the nature of coronal mass ejections.

The STEREO mission is currently funded until 2013.

“The probes have enough fuel to last 100 years,” said Gurman. “The lifetime limiting factor is the spacecraft electronics and funding. The solar arrays will only gradually degrade over decades.”

NASA/STEREO Reveals the Entire Sun

Launched in October 2006, STEREO traces the flow of energy and matter from the sun to Earth. It also provides unique and revolutionary views of the sun-Earth system. STEREO, when paired with SDO, can now give us the first complete view of the sun’s entire surface and atmosphere

On Super Bowl SUNday - Feb 6, 2011;
The two NASA STEREO spacecraft will see the entire Sun ! Super Bowl SUNday will truly mark a milestone for solar observations. On February 6, the two STEREO spacecrafts will be 180 degrees apart and for the next 8 years the STEREO spacecrafts and SDO will be able to observe the entire 360 degrees of the Sun. Credit: NASA
Positions of STEREO A and B for 6-Feb-2011 17:00 UT. This figure plots the current positions of the STEREO Ahead (red) and Behind (blue) spacecraft relative to the Sun (yellow) and Earth (green). The dotted lines show the angular displacement from the Sun. Units are in A.U.

NASA Robot and First Whole Sun Picture .. Coming on Super Bowl SUNday

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What do NASA, Robots, the Sun and the NFL have in common ?

Well … its Super SUNday … for Super Bowl XLV on Feb. 6, 2011

The unlikely pairing of Football and Science face off head to head on Super Bowl SUNday. Millions of television viewers will see NASA’s Robonaut 2, or R2, share the the limelight with the Steelers and the Packers of the NFL. The twin brother of R2 is destined for the International Space Station (ISS) and will become the first humanoid robot in space. It will work side by side as an astronaut’s assistant aboard the space station.

The fearsome looking R2 is set to make a first ever special guest appearance during the FOX Networks Super Bowl pre-game show with FOX sports analyst Howie Long. The pre-game show will air starting at 2 p.m. EST on Feb. 6.

And there’s more.

The Sun from Stereo B. Credit: NASA
On Super SUNday Feb. 6, NASA will publish Humankinds first ever image of the ‘Entire Sun’ courtesy of NASA’s twin STEREO spacecraft. And given the stunningly cold and snowy weather in Dallas, the arrival of our Sun can’t come soon enough for the ice covered stadium and football fans. See photos above and below.

The two STEREO spacecraft will reach positions on opposite sides of the Sun on Sunday, Feb. 6 at about 7:30 p.m. in the evening, possibly coinciding with the Super Bowl half time show.

At opposition, the STEREO duo will observe the entire 360 degrees sphere of the Sun’s surface and atmosphere for the first time in the history of humankind.

The nearly identical twin brother of R2 is packed aboard Space Shuttle Discovery and awaiting an out of this world adventure from Launch Pad 39 A at NASA’s Kennedy Space Center (KSC) in Florida. Blast off of the first humanoid robot is currently slated for Feb. 24.

R2 is the most dextrously advanced humanoid robot in the world and the culmination of five decades of wide-ranging robotics research at NASA and General Motors (GM).

This newest generation of Robonauts are an engineering marvel and can accomplish real work with exceptionally dexterous hands and an opposable thumb. R2 will contribute to the assembly, maintenance and scientific output of the ISS

“R2 is the most sophisticated robot in the world,” says Rob Ambrose, Chief of NASA’s Johnson Space Center’s (JSC) Robotics Division.

“We hope R2 should help to motivate kids to study science and space,” Ron Diftler told me in an interview at KSC. Diftler is NASA’s R2 project manager at JSC.

Fearsome Robonaut 2 at NASA’s Kennedy Space Center prepares to meet the NFL’s best players at Super Bowl XLV on Feb 6, 2011. Credit: Ken Kremer

The amazingly dexterity of the jointed arms and hands enables R2 to use exactly the same tools as the astronauts and thereby eliminates the need for constructing specialized tools for the robots –saving valuable time, money and weight.

The robot is loaded with advanced technology including an optimized overlapping dual arm dexterous workspace, series elastic joint technology, extended finger and thumb travel, miniaturized 6-axis load cells, redundant force sensing, ultra-high speed joint controllers, extreme neck travel, and high resolution camera and IR systems.

R2 weighs some 300 pounds and was manufactured from nickel-plated carbon fiber and aluminum. It is equipped with two human like arms and two hands as well as four visible light cameras that provide stereo vision with twice the resolution of high definition TV.

“With R2 we will demonstrate ground breaking and innovative robotics technology which is beyond anything else out there and that will also have real world applications as GM works to build better, smarter and safer cars,” according to Susan Smyth, GM Director of Research and Development.

“Crash avoidance technology with advanced sensors is a prime example of robonaut technology that will be integrated into GM vehicles and manufacturing processes.”

A team of engineers and scientists from NASA and GM pooled resources in a joint endeavor to create Robonaut 2, the most dexterously advanced robot in history. The NASA/GM team is pictured here at the Kennedy Space Center. R2 will fly aboard Space Shuttle Discovery with the STS-133 crew of humans and become the first humanoid robot in space.
R2 will become an official ISS crew member. Credit: Ken Kremer

Robonaut 2 flight unit poses with the NASA/GM development team inside the Space Station Processing Facility at KSC in this 360 degree panorama from nasatech.net

I was fortunate to meet R2 and the Robonaut team at KSC. R2 is incredibly life like and imposing and I’ll never forget the chance to shake hands. Although its motions, sounds, illuminated hands and muscular chest gives the unmistakable impression of standing next to a lively and powerful 300 pound gorilla, it firmly but gently grasped my hand in friendship – unlike a Terminator.

So its going to make for a mighty match up some day between the fearsome looking R2 and the NFL players.

Well apparently, R2 and Howie will be making some predictions on which player will win the MVP award and a GM Chevrolet. Stay tuned.

So come back on SUNday Feb. 6 for NASA’s release of the first ever images of our entire Sun from the STEREO twins.

Clash of the Titans - R2 and NASA robotics engineer at football practice at KSC. Credit: Ken Kremer
Space Shuttle Discovery awaits launch from Pad 39 A at the Kennedy Space Center, Florida. Robonaut 2 is loaded inside the Leonardo storage module which will be permanently attached to the ISS by the STS-133 crew. Credit: Ken Kremer
On Super Bowl SUNday - Feb 6, 2011 - the two NASA STEREO spacecraft
will see the entire Sun for the first time! Credit: NASA.

First Ever Whole Sun View .. Coming Soon from STEREO

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“For the first time in the history of humankind we will be able to see the front and the far side of the Sun … Simultaneously,” Madhulika Guhathakurta told Universe Today. Guhathakurta is the STEREO Program Scientist at NASA HQ.

Courtesy of NASA’s solar duo of STEREO spacecraft.

And the noteworthy event is timed to coincide just perfectly with ‘Super Bowl SUNday’ – Exactly one week from today on Feb. 6 during Super Bowl XLV !

“This will be the first time we can see the entire Sun at one time,” said Dean Pesnell, NASA Solar Astrophysicist in an interview for Universe Today. Pesnell is the Project Scientist for NASA’s Solar Dynamics Observatory at the NASA Goddard Spaceflight Center in Greenbelt, MD.

This remarkable milestone will be achieved when NASA’s two STEREO spacecraft reach position 180 degrees separate on opposite sides of the Sun on Sunday, Feb. 6, 2011 and can observe the entire 360 degrees of the Sun.

“We are going to celebrate by having a football game that night!” Pesnell added in jest.

The nearly identical STEREO spacecraft – dubbed STEREO Ahead and STEREO Behind – are orbiting the sun and providing a more complete picture of the Suns environment with each passing day. One probe follows Earth around the sun; the other one leads the Earth.

STEREO is the acronym for Solar TErrestrial RElations Observatory. Their mission is to provide the very first, 3-D “stereo” images of the sun to study the nature of coronal mass ejections.

Today, (Jan 30) the twin STEREO spacecraft are 179.1 degrees apart and about 90 degrees from Earth, and thus virtually at the midpoint to the back of the sun. See the orbital location graphics above and below.

Both probes were flung into space some four years ago and have been hurtling towards this history making date and location ever since. The wedge of unseen solar territory has been declining.

As the STEREO probes continue flying around to the back side of the sun, the wedge of unseen solar territory on the near side will be increasing and the SDO solar probe will play a vital gap filling role.

“SDO provides the front side view of the sun with exquisite details and very fast time resolution,” Gutharka told me. For the next 8 years, when combined with SDO data, the full solar sphere will still be visible.

The Whole Sun will be simultaneously Imaged for the First tIme ever on Super Bowl SUNday Feb. 6.
For the past 4 years, the two STEREO spacecraft have been moving away from the Earth and gaining a more complete picture of the sun. On February 9, 2011, NASA will hold a press conference to reveal the first ever images of the entire sun and discuss the importance of seeing all of our dynamic star.
Credit: NASA

The solar probes were launched together aboard a Delta II rocket from Launch Complex 17B at Cape Canaveral Air Force Station (CCAFS) in Florida on October 25, 2006. See Launch Video and Photos below.

Whole Solar Sphere A Goldmine for Science

I asked Pesnell and Guhathakurta to explain why this first ever whole Sun view is a significant scientific milestone.

“Until now there has always been an unseen part of the Sun,” Pesnell explained. “Although that unseen part has always rotated into view within a week or two, a global model must include all of the Sun to understand where the magnetic field goes through the surface.”

“Also, from the Earth we can see only one pole of the Sun at a time, while with STEREO we can see both poles at the same time.

“The next few years of overlapping coronal images will be a goldmine of information for predicting space weather at the Earth and understanding of how the Sun works. It is like getting the GOES images of the Earth for the first time. We haven’t missed a hurricane since, and now we won’t miss an active region on the Sun,” said Pesnell.

How will the science data collected be used to understand the sun and its magnetic field?

“Coronal loops trace out the magnetic field in the corona,” Pesnell elaborated. “Understanding how that magnetic field changes requires seeing where on the surface each loop starts and stops.”

Why is it important to image the entire Sun ?

“Once images of the entire Sun are available we can model the entire magnetic field of the Sun. This has become quite important as we are using STEREO and SDO to study how the entire magnetic field of the Sun reacts to the explosions of even small flares.”

“By seeing both poles we should be able to understand why the polar magnetic field is a good predictor of solar activity,” said Pesnell.

“Seeing both sides will help scientists make more accurate maps of global coronal magnetic field and topology as well as better forecasting of active regions – areas that produce solar storms – as they rotate on to the front side. Simultaneous observations with STEREO and SDO will help us study the sun as a complete whole and greatly help in studying the magnetic connectivity on the sun and sympathetic flares, ” Guhathakurta amplified.

Latest EUVI Images from STEREO. These Extreme Ultra Violet Images from STEREO Ahead and Behind were taken on Jan. 30, 2011. Credit: NASA

Watch a solar rotation animation here combining EUVI and SDO/AIA:

What is the role and contribution of NASA’s SDO mission and how will SDO observations be coordinated with STEREO?

“As the STEREO spacecraft drift around the Sun, SDO will fill in the gap on the near of the Sun,” explained Pesnell. “For the next 4 or more years we will watch the increase in sunspots we call Solar Cycle 24 from all sides of the Sun. SDO has made sure we are not doing calibration maneuvers for a few days around February 6.”

“On Feb 6th we will view 100% of the sun,” said Guhathakurta.

At a press conference on Feb. 9, 2011, NASA scientists will reveal something that no one has even seen – The first ever images of ‘The Entire Sun’. All 360 degrees

Watch the briefing on NASA TV at 2 PM EST

More about the SDO mission and SDO science
and Coronal holes from STEREO and SDO here

STEREO Website

“3D Sun”
A STEREO Movie in Digital and IMAX was released in 2007
Watch the way cool 3D IMAX trailer below

STEREO spacecraft location map

Caption: Positions of STEREO A and B for 31-Jan-2011 05:00 UT. The STEREO spacecraft are 179.2 degrees apart and about 90 degrees from Earth on Jan. 31, 2011. This figure plots the current positions of the STEREO Ahead (red) and Behind (blue) spacecraft relative to the Sun (yellow) and Earth (green). The dotted lines show the angular displacement from the Sun. Units are in A.U. (Astronomical Units). Credit: NASA

STEREO Launch Video

Launch Video Caption: The Delta II rocket lights the evening sky as STEREO heads into space on October 25, 2006 at 8:52 p.m. The Delta II rocket lights the evening sky as STEREO heads into space. STEREO (Solar Terrestrial Relations Observatory) is a multi-year mission using two nearly identical observatories, one ahead of Earth in its orbit and the other trailing behind. The duo will provide 3-D measurements of the sun and its flow of energy, enabling scientists to study the nature of coronal mass ejections and why they happen.

Fully fueled, technicians prepare the STEREO spacecraft for spin testing in the cleanroom in Titusville, Fl, while being prepared for launch. Credit: nasatech.net

Delta Launch Complex 17 comprises two launch pads and towers, 17 A & 17 B, at Cape Canaveral Air Force Station, FL. Credit: Ken Kremer
View of Delta II Launch Complex 17 by Ken Kremer

Fully clear of the smoke, STEREO streaks skyward during launch on October 25, 2006 from Pad 17B at Cape Canaveral, FL. Credit: nasatech.net

More STEREO Cleanroom and Launch photos from nasatech.net here

More about the SDO mission and SDO science
and Coronal holes from STEREO and SDO here

STEREO Website

“3D Sun”
A STEREO Movie in Digital and IMAX was released in 2007

Watch the way cool 3D trailer here – Trailer narrated by NASA’s Madhulika Guhathakurta
— be sure to grab hold of your Red-Cyan Glasses

Holes in the Sun’s Corona in 2 D, 3 D and Video

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A pair of coronal holes on the Sun newly imaged by NASA’s flagship solar probe, the Solar Dynamics Observatory (SDO) may cause auroral activity here on Earth soon.

The pair of holes were captured in images taken from Jan 9-12, 2011 by SDO’s AIA instrument in the extreme untraviolet (UV). The images – shown above and below – were also made into a cool timelapse video (shown below) of the rotating sun and were released by NASA as “SDO Pick of the Week” for Jan. 14, 2011.

SDO research results on the solar corona are featured as the cover photo and story for the current issue of Science magazine on Jan. 7, 2011. Updated

Science magazine Jan. 7 2011, COVER.
Multiwavelength extreme ultraviolet image of the Sun taken by the Solar Dynamics Observatory's Atmospheric Imaging Assembly. Colors represent different gas temperatures: ~800,000 kelvin (K) (blue), ~1.3 million K (green), and ~2 million K (red). New observations reveal a link between hot plasma and jets propelled upward from the region immediately above the Sun's surface and help explain why the Sun's outer atmosphere, or corona, is much hotter than its surface. Image: NASA/Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA)
Click to enlarge all images

Coronal holes on the sun’s surface are the source of open magnetic field lines and are areas from which high-speed solar wind particles stream out into space. The fast solar wind travels at approximately 800 km/s (about 1.8 million mph). After traveling through space for a few days the particles will impact the Earth and may spark the formation of some auroral activity for lucky spectators.

The two holes developed over several days. In a video here, one hole is above the suns equator and the other is below. According to a NASA press release, the coronal holes appear dark at the extreme UV wavelength of 193 Angstroms because there is just less of the material – ionized iron- that is being imaged.

2 D Video: A Hole in the Sun’s Corona

Caption: This timelapse video shows a coronal hole, as captured in ultraviolet light by NASA’s Solar Dynamics Observatory around Jan. 10, 2011. Coronal holes are areas of the sun’s surface that are the source of open magnetic field lines that head way out into space. They are also the source regions of the fast solar wind, which “blows” at a relatively steady clip of 1.8 million mph. (No audio). Credit: NASA

3 D Video: Coronal holes from STEREO

Check out this 3 D movie of a coronal hole snapped by NASA’s twin STEREO solar probes orbiting the sun. You’ll need to pull out your red-cyan 3 D anaglyph glasses. First, watch the short movie with you 3 D glasses. Then, I suggest to pause the movie at several intervals for a longer look. Remember – its red on the left eye.

View more 3 D from SDO below. And enjoy more 3 D space imagery here – at a big Martian crater through the eyes of the Opportunity rover.

Caption: This STEREO image features an active region and a coronal hole. The hole is the large dark spot in the middle of the sun. Coronal holes are the source of solar wind and a generator for space weather activity. Credit: NASA

More at this NASA press release

SDO roared to space on February 11, 2010 atop a powerful Atlas V rocket from Cape Canaveral Air Force Station in Florida. Launch photo below.

The billion dollar probe is the “crown jewel” in NASA’s solar fleet and will soon celebrate its first anniversary in space. SDO’s mission is to explore the Sun and its complex interior mechanisms in unprecedented detail. It is equipped with three science instruments (HMI, AIA, and EVE)

This Solar Dynamics Observatory image of the Sun taken on January 10, 2011 in extreme ultraviolet light captures a dark coronal hole just about at sun center. Coronal holes are areas of the Sun's surface that are the source of open magnetic field lines that head way out into space. Credit: NASA
SDO blast off on Feb. 11, 2010 atop Atlas V rocket from Pad 41 at Cape Canaveral as viewed from the KSC press site. Credit: Ken Kremer
Solar 3 D in Extreme UV - from SDO.
This 3 D image was created by combined two images that were taken in one extreme UV wavelength about 8 hours apart on June 25, 2010. The Sun's rotation created enough of a perspective change for this to work. Although the SDO mission cannot produce true 3D images of the Sun like STEREO, 3D solar images can still be made from SDO images. Credit: NASA/SDO

STEREO Catches Mercury Acting Like a Comet

The STEREO mission to study the Sun also has observed some unusual comet-like features exhibited by the planet Mercury, with a coma of tenuous gas surrounding the planet and a very long tail extending away from the sun. These types of features had been seen before from telescopes on Earth, but the STEREO observations are helping scientists to understand the nature of the emissions coming from Mercury, which might be different from what was previously thought.

Another note of interest: the tail in the STEREO data was actually discovered by a fellow blogger, Ian Musgrave, who writes Astroblog. He is a medical researcher in Australia who has a strong interest in astronomy. Viewing the on-line data base of STEREO images and movies, Dr. Musgrave recognized the tail and sent news of it to a team of astronomers from Boston University to compare it with their observations.

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The STEREO mission has two satellites placed in the same orbit around the Sun that the Earth has, but at locations ahead and behind it. This configuration offers multi-directional views of the electrons and ions that make up the escaping solar wind. On occasion, the planet Mercury appears in the field of view of one or both satellites. In addition to its appearance as a bright disk of reflected sunlight, a ‘tail’ of emission can be seen in some of the images.

From Earth-based telescopes, astronomers have seen how the Sun’s radiation pressure pushes sodium atoms from Mercury’s surface away from the planet – and away from the Sun – creating a tail that extends many hundreds of times the physical size of Mercury.

Much closer to Mercury, several smaller tails composed of other gases, both neutral and ionized, have been found by NASA’s MESSENGER satellite as it flew by Mercury in its long approach to entering into a stable orbit there.

“We have observed this extended sodium tail to great distances using our telescope at the McDonald Observatory in Texas,” Boston University graduate student Carl Schmidt explained, “and now the tail can also be seen from satellites near Earth.”

“What makes the STEREO detections so interesting is that the brightness levels seem to be too strong to be from sodium,” said Boston University graduate student Carl Schmidt, lead author on a paper that was presented at European Planetary Science Congress in Rome this week.

Now, the Boston University scientists are working with the STEREO scientists to try and sort everything out.

The current focus of the team is to sort out all of the possibilities for the gases that make up the tail. Dr. Christopher Davis from the Rutherford Appleton Laboratory in Chilton, England, a member of the STEREO team is working closely with the Boston University group on refining the brightness calibration methods, and determining the precise wavelengths of light that would get through the cameras’ filters.

“The combination of our ground-based data with the new STEREO data is an exciting way to learn as much as possible about the sources and fates of gases escaping from Mercury,” said Michael Mendillo, Professor of Astronomy at Boston University and director of the Imaging Science Lab where the work is being done.

“This is precisely the type of research that makes for a terrific Ph.D. dissertation,” Mendillo added.

Read the team’s paper: “Observations of Mercury’s Escaping Sodium Atmosphere by the STEREO Spacecraft”

Sources: European Planetary Science Congress, Boston University, Astroblog,