Sunspot, NM (Dec. 18, 2003) -- As last October's solar flares blossomed into a coronal mass ejections, scientists at the National Solar Observatory used a new set of instruments to record the sharpest-ever images of the heart of the storms.
"A stunning H-alpha flare movie was made and shows, to our knowledge for the first time, flare structure at scales of 0.2 arc-seconds," said Dr. Thomas Rimmele, project scientist for the NSO's Adaptive Optics (AO) project. In addition, the new Diffraction Limited Spectropolarimeter (DLSP) captured high-resolution polarization maps that are essential to studying the fine structure of magnetic activity on the Sun.
The DLSP, a joint project of the NSO and the High Altitude Observatory in Boulder, CO, is the first instrument designed to take advantage of the AO76 system. The story and high-resolution images are on line at
Related Web sites:
http://nicmosis.as.arizona.edu:8000/ECLIPSE_WEB/ECLIPSE_03/ECLIPSE_03.html
http://www.eclipses.info
No one has ever seen a total solar eclipse from over the Antarctic. But next Sunday, passengers on two separate chartered aircraft will get first-ever views of a total solar eclipse from high over a small slice of the South Polar continent.
University of Arizona astronomer Glenn Schneider helped plan the two aircraft intercepts of the Nov. 23 total solar eclipse, which won't be visible from land anywhere else on Earth.
Schneider will be in the navigator's seat on one of the aircraft, a chartered Qantas Boeing 747-400. It will carry solar eclipse chasers, scientists, photographers, amateur astronomers and tourists on a 14-hour, nonstop roundtrip flight out of Melbourne, Australia. Schneider has worked with Qantas pilots for the past several years in planning the special flight, arranged through Croydon Travel of Melbourne. He will assist the flight crew in navigating the plane through the moon's shadow during "totality," when the moon entirely blocks the sun.
Passengers in the moving aircraft might see totality for as long as 2 minutes, 36 seconds, if there is little or no wind, compared to less than 2 minutes that totality will last at ground sites. The eclipse occurs at 22:40 Universal Time (5:40 p.m. Eastern time), which is 9:40 a.m. Monday, Nov. 24, Melbourne time.
Schneider developed computer software called "EFLIGHT," a navigational program specifically for flying aircraft into the path of total eclipses. It helps pilots respond to real-time, in-flight conditions to get the best possible "totality run." He used EFLIGHT in planning two previous airborne missions that intercepted the total solar eclipses of Oct. 3, 1986, and June 30, 1992. He also planned to use EFLIGHT on the Concorde for a 2001 eclipse. But that flight was canceled after Air France grounded its Concorde fleet following a crash.
For the Nov. 23 eclipse, pilots on two aircraft will use EFLIGHT in their flight management systems. Schneider and the Qantas pilots conducted a dry-run test on the system last July in a 747 flight simulator. Meanwhile, Sky and Telescope magazine and Travelquest International chartered a Lan Chile Airbus A340 for the eclipse. That plane will fly out of Punta Arenas, Chile. Sky and Telescope recruited Schneider to assist planning its flight, too.
On the Qantas eclipse flight, Schneider will operate four cameras on a gyro-stabilized platform suspended over the flight deck by bungee cords. The cameras will be controlled by computer software that Schneider wrote, and a Sony video camera will guide the platform by feeding images to the computer system. Three still photo cameras will be used to photograph the eclipse: a Pentax ZX-5n equipped with a 500 mm f/5.6 lens, a Nikon F5 equipped with Nikon Vibration-Reduction 80-400 mm zoom, and a Santa Barbara Instrument Group 1024 x 1024 CCD digital camera with a 300 mm lens and special green filter. The filter is used to create better images of the sun's inner corona.=20
The camera equipment was provided by collaborators including Jay M. Pasachoff of Williams College. Pasachoff, who chairs the International Astronomical Union's Working Group on Eclipses, will be on the Qantas flight.
Schneider occasionally may have to blow on the camera platform if it begins to drift away from the 16-by-27-inch window that the cameras peer through. A breath of air is all that's needed -- touching the platform would send it swinging.
The B747-400 will fly at about 470 nautical mph at 38,000 feet. It will fly within a kilometer of the center of the moon's shadow, within 100 meters of its target vertical position, and within a 6-second time margin.
The moon's shadow, which is about 64 nautical miles across, moves at 2,200 nautical mph, or about 4-and-one-half times faster than the airplane. It will overtake the plane from behind.
"The moon's shadow will be projected down below us onto the cloud tops, so the snow and ice will be dark," Schneider said. "There will be no reflected sunlight coming back up. The sky will be black."
Scientists plan to make some unique light-scattering measurements on Earth's upper atmosphere during the flight, Schneider said. They will use the moon's shadow as an illumination probe to get information on particle distribution that they can=B9t get with remote sensing or LIDAR.
Schneider is an associate astronomer at the UA Steward Observatory. He also is the project instrument scientist for the NICMOS, the instrument that gives the Hubble Space Telescope its infrared vision.
Schneider describes himself as an "umbraphile," literally a "shadow lover," one who is "addicted to the glory and majesty of total solar eclipses." Umbraphillia "is not only an addiction, but an affliction, and a way of life, the real raison d'etre for many of us," Schneider said. Umbraphiles are commonly called "solar elipse chasers," people who once every 16 months or so "will drop whatever they are doing and trek by plane, ship, train, foot, and camel-back to gather along a narrow strip in some remote God-forsaken corner of the globe."
Because Schneider is willing to travel, he has seen 23 eclipses since 1970 and been clouded out only three times.
But travel often entails killer jet lag. The 14-hour eclipse flight returns to Melbourne at 3 p.m. local time. Schneider then will repack the cameras, gryo platform, computers, inverters, power supplies, etc. into shipping crates to catch an 8 a.m. flight the following morning -- the start of his 28-hour trip back to Tucson.
"I missed Thanksgiving last year because I was in the Australian outback for the last eclipse, and I promised my wife I'd be home for Thanksgiving this year," he said.
Macintosh users can download Schneider's software for photographing a solar eclipse, called "Umbraphile," from the Internet for free. Given the particulars of an eclipse, the program computes an exposure sequence table synced to Universal Time and automatically fires the camera at correct exposures. The software is online at:Scientists using the Solar and Heliospheric Observatory (SOHO) spacecraft have been able to monitor the activity of the recent powerful solar magnetic active regions that were hidden on the far side of the Sun as they rotated with the Sun to face the Earth again.
Principal Investigator Dr. Jean-Loup Bertaux and colleague Dr. Eric Quemerais of the Service d'Aeronomie in the Paris suburb of Verrieres le Buisson have found that the activity of the sunspot regions numbered 10486 and 10484 by the National Oceanic and Atmospheric Administration Space Environment Center (NOAA SEC) has decreased dramatically in recent days. However, even more recently (18 and 19 November), the activity of these active regions has increased again.
These giant active regions were on the side of the Sun facing the Earth during the period October 26 - November 4, when a series of intense flares and coronal mass ejections produced dramatic space weather effects. (There were eight X-class flares, the most intense classification of soft X-ray events measured by NOAA's GOES spacecraft, from the two giant regions.) On October 28, the shock wave driven by a very fast coronal mass ejection (CME) associated with an X28 flare accelerated electrically charged particles that affected spacecraft throughout the solar system.
The Sun rotates once every roughly 27 days at its equator: would these active regions appear again this week and create more problems for satellite operators? Until recently, the problem of knowing what was happening on the far side of the Sun appeared intractable. In 2000, however, researchers using both the Michelson Doppler Imager (MDI) and Solar Wind ANisotropies (SWAN) instruments on SOHO began producing data on farside activity. MDI uses a holographic reconstruction technique to map the presence of sunspot groups that modify the transmission of acoustic waves beneath the solar surface; SWAN is able to determine how "active" the regions are in the ultraviolet portion of the spectrum.
"Any hope of improving longer term forecasts of space weather requires an ability to monitor active regions as they transit the far side of the Sun," said Dr. Joseph Kunches of NOAA SEC. "SOHO instruments MDI, SWAN, and LASCO have demonstrated the ability to track active regions across the invisible disk in new ways, benefiting forecasters and users of space weather information."
"When we first proposed the SWAN instrument for SOHO in 1989,we wanted to study the science of the interaction of the solar wind with interstellar gas. Now, we are delighted to see that it could actually be useful outside the field of pure science, by improving the prediction of solar activity, which may impact many sectors of technology like spacecraft operations", said Bertaux.
SWAN can indirectly monitor the activity on the far side of the Sun as it maps the whole sky in ultraviolet light. A huge cloud of interstellar hydrogen that bathes the entire Solar System interacts with the solar wind, and lights up in the Lyman-alpha spectral line when it is hit by UV radiation from the Sun. Since active regions on the Sun are brighter in Lyman-alpha light, the part of the sky facing an active region is brighter. Just as a rotating lighthouse beam will illuminate different patches of fog, the Sun's rotation produces a changing pattern of Lyman-alpha illumination on the sky behind the Sun's far side. Any change in the solar activity is in this way directly reflected in the amount of Lyman-alpha emission that is observed by SWAN.
After October 28, the SWAN team started observing farside activity more intensively. They found that the Lyman-alpha sky brightness could be correlated with the "Mg II index," a measure of the integrated brightness of a strong spectral line of ionized magnesium in the Sun's outer atmosphere. The Mg II index is measured from earth-orbiting spacecraft such as the UARS and SORCE missions of NASA's Earth Science enterprise, and is a good measure of total solar activity.
The SWAN team used their data to estimate what the MgII index would be for an observer rotating with the Sun, and always facing a given active region during the solar rotation. The MgII index estimated from SWAN data increased up to November 7, but then began rapidly decreasing. The corresponding decrease of the solar Lyman-alpha brightness found by SWAN was 20%, an indication that the activity of the two active regions decreased significantly since their stunning performance on the near side of the Sun. This method should prove of value to space weather forecasters, who are just as interested in predicting "clear" days as they are in forecasting storms from the Sun. For images, refer to:NASA HQ Press Release: 03-214, June 24, 2003
The Solar and Heliospheric Observatory (SOHO) spacecraft expects to experience a blackout in the transmission of its scientific data this week. It is estimated the blackout may last two to three weeks.
Engineers are predicting this problem after detecting a malfunction in the pointing mechanism of the satellite's high-gain antenna (HGA), which is used to transmit the large amounts of data from SOHO's scientific observations to Earth.The SOHO spacecraft is operating as safely as before the problem occurred. Its low gain antenna, which does not need to be pointed in a specific direction, will be used to control SOHO, monitoring spacecraft and instrument health and safety.
The anomaly in the HGA was recently discovered when engineers detected a discrepancy between the commanded and measured antenna position. In normal conditions, the antenna must be able to move along two axes, vertical and horizontal. The horizontal movement is no longer taking place properly. The problem is probably due to a malfunction in the motor or gear assembly that steers the antenna.
SOHO is located 1.5 million kilometers (one million miles) from Earth. It orbits around the First Lagrangian point, where the combined gravity of the Earth and the sun keep SOHO in an orbit locked to the sun-Earth line. To transmit data, the SOHO HGA must rotate to have Earth in its field of view.
If the problem is not solved, the Earth will be left outside the HGA beam on a periodic basis, with similar blackouts occurring every three months. European Space Agency (ESA) and NASA engineers are assessing several options to recover the situation, or minimize the scientific data loss.
SOHO is a project of international cooperation between ESA and NASA to study the sun, from its deep core to the outer corona, and the solar wind. It was launched in December 1995 on an Atlas IIAS/Centaur rocket. Besides watching the sun, SOHO has become the most prolific discoverer of comets in astronomical history. As of May 2003, more than 620 comets have been found by SOHO.
COLUMBIA, MD. (June 19, 2003) -- For scientists who study solar flares, the hottest spots in the solar system just got substantially hotter.
The hottest spots in solar flares reach temperatures as much as 20 million degrees Fahrenheit hotter than solar physicists had previously believed, topping out at more than 80 million degrees Fahrenheit. And from about 5 million degrees just before a flare, in less than a minute temperatures in the sun's atmosphere can warm by more than 75 million degrees.
Using data gathered by NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), scientists from The University of Alabama in Huntsville (UAH), the University of Glasgow and the University of California at Berkeley were able to isolate and measure sources of the most powerful X-rays emitted by a solar flare on July 23, 2002.
"Previously the best we could do was look at an average temperature for the entire flare," said Dr. Gordon Emslie, who is scheduled to present the findings today at a meeting of the American Astronomical Society's Solar Physics Division in Columbia, MD. "With RHESSI we get an incredible amount of data. One of the things we can do with that is look at the hottest point sources within a flare.
"We have been able to take a picture of the hot spot and the data from that 'ups the ante' considerably."
RHESSI images of the flare show a bright "blob" suspended 7,000 miles above the sun. Below it are three hot spots on the solar surface.
"This suspended blob is extremely hot," said Emslie, a physics professor at UAH. "That's where the temperature hit 45 million kelvins -- about 80,000,000 degrees Fahrenheit, give or take a million. We think the other three bright spots are where electrons from that hot blob are being slammed into the surface. And when they hit they release energy in the form of X rays."
These findings will force Emslie and other solar physics theorists to re-examine the theories they have developed to explain the most massive explosions in the solar system.
"Now we have to stop talking about 30 million kelvins and start thinking about 40 or 45 million kelvins," he said. "That represents a bigger concentration of energy, which has to be explained in our theories and our models."
The power released by a large solar flare--such as the one on June 23, 2002--would be measured in the billions of trillions of kilowatts. If certain types of flares erupt on the side of the sun facing Earth, waves of electromagnetic energy can disrupt telecommunications, black out power systems, and play havoc with satellites. It might even endanger astronauts working outside a space shuttle or space station.
Solar activity has caused power outages in Canada, and blurred TV and telephone signals bounced off satellites. Magnetic storms cause power outages when waves of electromagnetic particles from the sun hit power lines and electrical transformers. Just as electrical power is generated on the sun by the interaction of magnetic fields, electromagnetic fields from the sun induce electrical current in transformers and power lines on Earth. Those extra surges of power can trip circuit breakers and shut down power systems.
"If we're ever going to be able to predict these things, we have to understand them better," said Emslie. "And RHESSI is helping us do that."
http://www.uah.edu/News/2003news/x-ray.html
The Solar Physics Branch at the Naval Research Laboratory is pleased to announce the release of the web site of its latest sounding rocket payload; the Very high Angular resolution Ultraviolet Telescope (VAULT). VAULT is an imaging instrument that obtains narrowband images of the solar atmosphere in the Lyman alpha line (1216A) with the unprecedented resolution of 0.3 arcseconds (or 220 km). VAULT has flown twice as a sounding rocket payload and is the successor of the NRL's highly successful High Resolution Telescope and Spectrograph (HRTS). The VAULT web site can be accessed at http://wwwsolar.nrl.navy.mil/rockets/vault/index.html. We have taken care to make the site accessible and interesting to both the general public and the solar physics community. The public can find an extensive collection of information, visualizations and images that describe the concept of sounding rockets, the VAULT instrument and its scientific objectives and of course the spectacular images obtained during the flights. The site also contains the full set of data (in FITS format) from the first flight of the instrument. They are freely available to all interested parties for further scientific analysis. We plan to add the data from the second flight of the instrument in the near future. The site will be continuously updated with results and images from the ongoing data analysis efforts and future flights. We welcome comments and suggestions for improving the site. Please visit often.
Clarence Korendyke (Principal Investigator)
Angelos Vourlidas (Project Scientist)
Code 7660, Naval Research Laboratory
Washington, DC 20375
for further information,please contact: vourlidas@nrl.navy.mil
The December 4 total solar eclipse was observed by professionals, amateurs, tourists, and locals in southern Africa and southern Australia. Heavy clouds prevented many from seeing it, but holes in the clouds at many locations and clear weather at the end of the path meant that many of the travellers had an excellent view. The Sun had a round, bright configuration that is typical of the maximum of the solar-activity cycle. Several prominences were visible in addition to the many coronal streamers.
See www.williams.edu/astronomy/ecliplse.
One of our images, compounded with an image from the SOHO spacecraft, was released
by NASA as http://www.gsfc.nasa.gov/topstory/2002/1204eclipse.html.
See the link to Web sites for more information and images: Eclipse
2002 Web Sites.
See an animation of the previous total eclipse (2001) at http://antwrp.gsfc.nasa.gov/apod/ap021209.html
ESA Press Release, May 21, 2002
For centuries, we have worshipped it and wondered at it, but it's only now that we are getting a really good look at it. Although you can't gaze at the Sun with the naked eye, thanks to modern science, in particular ESA's solar fleet, we can view images of our nearest star that confirm the fiery glory our ancestors could only imagine.
Remarkable imagery from ESA's SOHO spacecraft is the inspiration behind Sunsation - an exhibition that seeks to bring our vision of the Sun up to date by combining the most stunning solar images from space with other images from our everyday world.
Read more about this at:
http://sci.esa.int/content/news/index.cfm?aid=1&cid=1&oid=29995
and visit the
Sunsation exhibition at:
http://sunsation.esa.int/
Just in time for Sun-Earth Day, a new NASA spacecraft, complete with a new name, made its debut by observing a huge explosion in the atmosphere of the Sun. The blast, called a solar flare, was equal to one million megatons of TNT and gave off powerful bursts of X-rays.
The solar fireworks were captured by what is now known as the Reuven Ramaty High-Energy Solar Spectroscopic Imager spacecraft, or RHESSI. The spacecraft launched last month as HESSI was recently renamed in honor of Dr. Reuven Ramaty, who died in 2001 after a long and distinguished career in the Laboratory for High Energy Astrophysics at the NASA Goddard Space Flight Center, Greenbelt, Md. Ramaty was a pioneer in the field of solar-flare physics, gamma-ray astronomy and cosmic rays.
"We are thrilled to be making the first high-resolution movies of flares using their high-energy radiation," said Brian Dennis, the RHESSI mission scientist at Goddard. "We want to understand how solar flares can explosively release so much energy. RHESSI shows us the high-energy radiation emitted by flares: their X-rays and gamma rays. This radiation reveals the core of the flare -- the exact time and place where the energy is released."
Scientists believe solar flares are powered by the violent release of magnetic energy, but how this happens is unknown. A new movie features one of the first flares recorded by RHESSI, which occurred Feb. 20 in the southern hemisphere of the Sun, an active region designated "AR 9830."
It was a moderately powerful flare, classified as M2.4 by the National Oceanic and Atmospheric Administration (NOAA). The most powerful flares, designated X-class by NOAA, can release up to 1,000 times more energy.
During its planned two-year mission, RHESSI will study the secrets of how solar flares are produced in the Sun's atmosphere. Launched Feb. 5, RHESSI is now fully operational after only six weeks in orbit. It is observing the Sun and recording the high-energy radiation from solar flares as they occur.
RHESSI is the first NASA Small Explorer mission being managed in the "Principal Investigator" mode. The Principal Investigator, Robert Lin of the University of California, Berkeley, is responsible for most aspects of the mission, including the science instrument, spacecraft integration and environmental testing, and spacecraft operations and data analysis.
The RHESSI scientific payload is a collaborative effort among the University of California, Berkeley; Goddard; the Paul Scherrer Institut in Switzerland; and the Lawrence Berkeley National Laboratory in Berkeley. The mission also involves additional scientific participation from France, Japan, The Netherlands, Scotland and Switzerland.
A movie of the flare recorded by the RHESSI spacecraft is available on the Internet at: http://www.gsfc.nasa.gov/topstory/20020320hessixray.html
RHESSI data are now
available online to the general public at:
http://hesperia.gsfc.nasa.gov/hessi/
NASA'S High Energy Solar Spectroscopic Imager, or HESSI, lifted off on February 5, 2002, from Cape Canaveral Air Force Station, Fla. at 2:29 p.m. EST. During its planned two-year mission HESSI will study the secrets of how solar flares are produced in the Sun's atmosphere.
Tucked inside a Pegasus XL rocket, attached to the under belly of the Orbital Stargazer L-1011 aircraft, the spacecraft was carried approximately 113 nautical miles east-southeast of the Cape to an altitude of about 39,000 feet. The Pegasus drop occurred at 3:56 p.m. EST, and after a short powered sequence, delivered the 645-pound HESSI spacecraft into a circular orbit 373 miles above the Earth, inclined at 38 degrees to the equator.
"We're extremely thrilled to report the Pegasus drop went without a hitch," said Frank Snow, HESSI Project Manager at NASA's Goddard Space Flight Center, Greenbelt, Md.
HESSI will help unlock some of the secrets of these gigantic explosions in the Sun's atmosphere, providing scientists with the first high-fidelity color movies of solar flares in X-rays and gamma rays, which is their highest energy emissions. Scientists hope to capture hundreds of X-ray and gamma ray flares during the spacecraft's planned two-year mission.
Science operations should begin in about three weeks, after germanium detectors inside the X-ray/gamma-ray imaging spectrometer are cooled to their operating temperature of minus 320 degrees Fahrenheit, turned on and checked out.
HESSI is the first NASA Small Explorer mission being managed in the 'principal investigator' mode. Professor Robert Lin of the University of California, Berkeley, is responsible for many aspects of the mission, including the science instrument, spacecraft integration and environmental testing, and spacecraft operations and data analysis.
The HESSI scientific payload is a collaborative effort between the University of California, Berkeley, NASA's Goddard Space Flight Center, the Paul Scherrer Institut in Switzerland, and the Lawrence Berkeley National Laboratory in Berkeley. The mission also involves scientific participation from France, Japan, The Netherlands, Scotland, and Switzerland.
The Explorers Program Office at Goddard manages the HESSI mission for NASA's Office of Space Science in Washington, D.C. Spectrum Astro, Inc. of Gilbert, Ariz., constructed the HESSI spacecraft and provided integration support.
The HESSI mission cost, including the spacecraft, science instrument, launch vehicle, and mission operations and data analysis, is approximately $85 million.
For additional details about the mission, go to:
http://hesperia.gsfc.nasa.gov/hessi
http://hessi.ssl.berkeley.edu
Scientists now have the first clear picture of what lies beneath sunspots, enigmatic planet-sized dark areas on the Sun's surface, and have peered inside the Sun to see swirling flows of electrified gas or plasma that create a self-reinforcing cycle, which holds a sunspot together.
The new research, gathered from the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft, will deepen understanding of the stormy areas on the Sun in which sunspots appear. Vast explosions associated with these active magnetic regions occasionally affect high-technology systems.
Sunspots have fascinated people since Galileo's observations of them contradicted the common belief that heavenly objects were flawless. Sunspots remain mysterious because at first glance, it seems they should rapidly disappear. Instead, they persist for weeks or more. "They obey what is a fundamental finding of observational science: Anything that does happen, can happen," said Philip Scherrer of Stanford University, Palo Alto, Calif., Principal Investigator for SOHO's MDI. "We now have a hint at 'how.'"
Astronomers know sunspots are regions where magnetic fields become concentrated. Yet, anyone who played with magnets as a child has felt how magnetic fields of like polarities repel each other. The strong solar magnetic fields should naturally repel each other also, causing the sunspot to dissipate. In fact, observations show that surface material clearly flows out of the spots.
Alexander Kosovichev and Junwei Zhao of Stanford University and Thomas Duvall of NASA's Goddard Space Flight Center, Greenbelt, Md., used MDI's unique ability to look just below the sunspot's surface and clearly observed inward-flowing material for the first time. The Astrophysical Journal published their research August 10.
"We discovered that the outflowing material was just a surface feature," said Zhao. "If you can look a bit deeper, you find material rushing inward, like a planet-sized whirlpool or hurricane. This inflow pulls the magnetic fields together."
Solar astronomers have long known that the intense magnetic field below a sunspot strangles the normal up-flow of energy from the hot solar interior, leaving the spot cooler and therefore darker than its surroundings. The suppression of the bubbling convective motions forms a kind of plug that prevents some of the energy in the interior from reaching the surface.
The material above the plug cools and becomes denser, causing it to plunge downward at up to 3,000 miles per hour, according to the new observations. That draws the surrounding plasma and magnetic field inward toward the sunspot's center. The concentrated field promotes further cooling, and as that cooling plasma sinks it draws in still more plasma, thereby setting up a self-perpetuating cycle. As long as the magnetic field remains strong, the cooling effect will maintain an inflow that makes the structure stable. The superficial outflows seen right at the surface are confined to a very narrow layer.
Since the magnetic plug prevents heat from reaching the solar surface, the regions beneath the plug should become hotter. A June 1998 observation provided evidence for this also. "We were surprised at how shallow sunspots are," said Kosovichev. Below 3,000 miles the observed sound speed was higher, suggesting that the roots of the sunspots were hotter than their surroundings, just the opposite of the conditions at the surface. "The cool part of a sunspot has the shape of a stack of two or three nickels," he added.
"The cool downward flows dissipate at the same depth where the hot upward flows diverge," said Duvall. "With these data one cannot get a sharp enough picture to really explain the details. Until now we've looked down at the top of sunspots like we might look down at the leaves in treetops. For the first time we're able to observe the branches and trunk of the tree that give it structure. The roots of the tree are still a mystery."
MDI explores beneath the surface of the Sun by analyzing sound-generated ripples at its surface using a technique called acoustic tomography -- a novel method similar to ultrasound diagnostics in medicine that use sound waves to image structures inside the human body. SOHO continues to mark an era of successful partnership between the European Space Agency and NASA within the Solar Terrestrial Science program.
Images and more
information are available at:
http://www.gsfc.nasa.gov/topstory/20010919sunspot.html
A photograph by Thierry Legault of an MD-11 airliner 35-km away silhouetted in front of an H-alpha view of the sun.
http://perso.club-internet.fr/legault/s010113.jpg
An on-line discussion of the use of the photo in teaching appears at
http://mailgate.nau.edu/cgi-bin/wa?S2=phys-l&q=&s=interesting+pic&f=&a=& b=
The latest values of the solar constant as measured by the VIRGO
experiment on SOHO, along with past measurements from several
spacecraft, are available on line at
http://www.pmodwrc.ch/solar_const/solar_const.html from the World
Radiation Center in Davos, Switzerland.
A new solar imaging service.
Goal: To provide a highly contiguous and high-cadence permanent daily 24-hour hydrogen alpha movie of the Sun.
We are presently collaborating with the National Solar
Observatory/Sacramento Peak at Sunspot, New Mexico, and the Kanzelhohe
Solar Observatory of the Institute of Geophysics, Astrophysics and
Meteorology at the University of Graz, Austria. These two observatories
alone are capable of providing up to approximately 21 hours of coverage
per day when cloudless. In order to help ensure the most contiguous
coverage possible during cloudy periods, we need imagery from other
locations as well. Our server automatically selects and uses the best
cloud-free images. The latest H-alpha image from this service is
available at the URL:
http://www.spacew.com/sunnow.
The web page is automatically updated with the latest image every
minute.
MPEG movies based on the last 60 received images are updated every 30
minutes and are available at:
http://www.spacew.com/sunnow/sunmovie.html
All movies are 512x512 pixels.
We should be able to keep about six months to one year of data on-line. The rest will be kept off-line and will be available by request. This will be a permanently available, public-domain resource to the science community.
The Japanese/US Solar B spacecraft to be launched in 2004 will carry a set of visible-light, extreme ultraviolet, and x-ray telescopes.
http://sohoftp.nascom.nasa.gov/~shaugan/hotshot/1999_09_14/
The Yohkoh Public Outreach Project (YPOP) is a NASA funded educational outreach project designed to facilitate public access to high quality Yohkoh/SXT and other solar data via the Internet.
A Yohkoh/SXT long-term movie can be accessed via
http://www.lmsal.com/YPOP/FilmArchives/data_access.html
Another feature you might find of interest is the weekly Yohkoh science nugget from the SXT Chief Observer at ISAS. This can be found at
http://isass1.solar.isas.ac.jp/sxt_co/index.html
The general outreach site can be accessed via http://www.lmsal.com/YPOP/
and is full of interesting activities and information.
The site is located at http://davinci.csun.edu/%7Eastro/sfo.html.
