STEREO | What's New


03/14/2018 07:00 PM
3 NASA Satellites Recreate Solar Eruption in 3-D

The more solar observatories, the merrier: Scientists have developed new models to see how shocks associated with coronal mass ejections, or CMEs, propagate from the Sun - an effort made possible only by combining data from three NASA satellites to produce a much more robust mapping of a CME than any one could do alone.

01/10/2018 07:00 PM
Magnetic coil springs accelerate particles on the Sun

In April and July 2014, the Sun emitted three jets of energetic particles into space, that were quite exceptional: the particle flows contained such high amounts of iron and helium-3, a rare variety of helium, as have been observed only few times before. STEREO observations enabled researchers to determine the sources of these energetic particles.

12/19/2017 07:00 PM
STEREO images show the Sun's Outer Atmosphere is More Complex than Previously Thought

The outer part of the Sun's atmosphere, the corona, looks pretty smooth, but new deep exposures of the outer corona reveal complex structures. This should make for some interesting observations from the upcoming Parker Solar Probe Mission (to be launched in 2018), which will be flying right through these regions.

11/02/2017 07:00 PM
Return of the Comet: 96P Spotted by ESA, NASA Satellites

Sun-gazing missions SOHO and STEREO watched the return of comet 96P/Machholz when it entered their fields of view between Oct. 25-30. It is extremely rare for comets to be seen simultaneously from two different locations in space, and these are the most comprehensive parallel observations ever taken of this comet.

10/02/2017 07:00 PM
Comet 96P/Machholz

The STEREO and SOHO Teams are gearing up for a planned visit by one of our favorite celestial wanderers! The comet 96P/Machholz should be in the STEREO field of view October 26-28. SOHO will be seeing it at the same time, giving us simultaneous views of 96P from two different locations in space!

10/02/2017 07:00 PM
Calling all Citizen Scientists!

Want to help solar scientists use STEREO data to better understand Coronal Mass Ejections? You can do that, with no previous experience required. The Solar Stormwatch Project is looking for volunteers who want to help analyze these giant solar storms as they move through the solar system. For more info about how to participate check out the Solar Stormwatch web page.

03/30/2017 07:00 PM
Waves on Sun Give New Insight into Space Weather Forecasting

STEREO and SDO observations of the solar poles reveal large scale waves that could help us predict the locations of future solar active regions.

01/31/2017 07:00 PM
NASA's Fermi Sees Gamma Rays from 'Hidden' Solar Flares with help from STEREO

An international science team says NASA's Fermi Gamma-ray Space Telescope has observed high-energy light from solar eruptions located on the far side of the sun, which should block direct light from these events. This apparent paradox is providing solar scientists with a unique tool for exploring how charged particles are accelerated to nearly the speed of light and move across the sun during solar flares. Thanks to the STEREO spacecraft, which were monitoring the solar far side when the eruptions occurred, the Fermi events mark the first time scientists have direct imaging of beyond-the-limb solar flares associated with high-energy gamma rays.

10/19/2016 07:00 PM
SUN 360: Our Solar System's Space Weather Watchdog

Join us for a series of presentations celebrating STEREO and efforts to predict space weather on the 10th anniversary of STEREO's launch, October 25, at 1:00 pm EDT. A panel of scientists including scientist-astronaut John Grunsfeld will discus how monitoring the Sun from widely different angles simultaneously can provide early warnings of explosive events on the Sun. The event will held at the National Air and Space Museum in Washington DC and will also be streamed on line and archived for future viewing.

09/05/2016 07:00 PM
Images From Sun's Edge Reveal Origins of Solar Wind

Ever since the 1950s discovery of the solar wind - the constant flow of charged particles from the sun - there's been a stark disconnect between this outpouring and the sun itself. As it approaches Earth, the solar wind is gusty and turbulent. But near the sun where it originates, this wind is structured in distinct rays, much like a child's simple drawing of the sun. The details of the transition from defined rays in the corona, the sun's upper atmosphere, to the solar wind have been, until now, a mystery.

08/28/2016 07:00 PM
A NASA Satellite Ends the Silent Treatment

NASA has re-established contact with an errant spacecraft. In October 2006, the space agency sent twin satellites into orbit to study the Sun. The satellites follow Earth's orbit around the sun, one ahead of us and one behind: STEREO-A and STEREO-B.

08/21/2016 07:00 PM
NASA Establishes Contact With STEREO Mission

On Aug. 21, 2016, contact was reestablished with one of NASA's Solar Terrestrial Relations Observatories, known as the STEREO-B spacecraft, after communications were lost on Oct. 1, 2014. Over 22 months, the STEREO team has worked to attempt contact with the spacecraft. Most recently, they have attempted a monthly recovery operation using NASA's Deep Space Network, or DSN, which tracks and communicates with missions throughout space.

04/28/2016 07:00 PM
Seeing Double: NASA Missions Measure Solar Flare from 2 Spots in Space

Solar flares are intense bursts of light from the sun. They are created when complicated magnetic fields suddenly and explosively rearrange themselves, converting magnetic energy into light through a process called magnetic reconnection at least, that's the theory, because the signatures of this process are hard to detect. But during a December 2013 solar flare, three solar observatories captured the most comprehensive observations of an electromagnetic phenomenon called a current sheet, strengthening the evidence that this understanding of solar flares is correct.

12/10/2015 07:00 PM
Saving NASA's STEREO-B: The 189-million-mile Road to Recovery

On Oct. 1, 2014, NASA lost communication with one of two STEREO missions spacecraft, just as the satellite was about to orbit around the other side of the sun. More than a year's worth of silence later, the spacecraft has finally emerged into a region where it can again receive signals -- and scientists have a plan to get it back.

11/18/2015 07:00 PM
NASA's STEREO-A Resumes Normal Operations

On Nov. 9, 2015, NASAÕs Solar and Terrestrial Relations Observatory Ahead, or STEREO-A, once again began transmitting data at its full rate. For the previous year, STEREO-A was transmitting only a weak signal or occasionally none at all due to its position almost directly behind the sun. Subsequently, as of Nov. 17, STEREO resumed its normal science operations, which includes transmission of lower-resolution real-time data used by scientists to monitor solar events as well as high-definition, but delayed, images of the sun's surface and atmosphere.

10/15/2015 07:00 PM
Comet Encke: A Solar Windsock Observed by NASA's STEREO

Much like the flapping of a windsock displays the quick changes in wind's speed and direction, called turbulence, comet tails can be used as probes of the solar wind - the constant flowing stream of material that leaves the sun in all directions. According to new studies of a comet tail observed by STEREO, the vacuum of interplanetary space is filled with turbulence and swirling vortices similar to gusts of wind on Earth. Such turbulence can help explain two of the wind's most curious features: its variable nature and unexpectedly high temperatures.

10/13/2015 07:00 PM
Blast waves in the Sun's atmosphere

Two teams of researchers led by Nariaki Nitta from the Lockheed Martin Advanced Technology Center in the USA and by Radoslav Buck from the Max Planck Institute for Solar System Research (MPS) in Germany have independently discovered a new solar phenomenon: large-scale waves in the star's atmosphere accompanied by energetic particle emissions rich in helium-3. Helium-3 is a light variety of the inert gas helium. The huge waves may contribute significantly to accelerate the particles into space, the MPS scientists now report in The Astrophysical Journal. Decisive for this discovery were the two spacecraft STEREO A and ACE making it possible to simultaneously observe the Sun from two different directions. In the near future, no such opportunity will arise again.

07/15/2015 07:00 PM
NASA Cites the Return of the STEREO-A Spacecraft

On July 11, 2015 we received our first images in over three months from NASA's Solar TErrestrial RElations Observatory Ahead spacecraft, or STEREO-A. Since March 24, 2015, STEREO-A has been on the far side of the sun, where it has had to operate in safe mode, collecting and saving data from its radio instrument.

The three-month safe mode period was necessary because of the geometry between Earth, the sun, and STEREO-A. STEREO-A orbits the sun as Earth does, but in a slightly smaller and faster orbit. The orbit ensured that over the course of years, Earth and the spacecraft got out of sync, with STEREO-A ending up on the other side of the sun from Earth, where it could show us views of our star that we couldnÕt see from home. Though the sun only physically blocked STEREO-A from EarthÕs line of sight for a few days, STEREO-A was close enough to the sunÑfrom our perspective -- that from March 24 until July 8, the sun interfered with STEREO-AÕs data transmission signal, making it impossible to interpret.

02/04/2015 07:00 PM
STEREO going into "safe mode" on far side of Sun

The IMPACT, PLASTIC, and SECCHI instruments on STEREO Ahead were turned off at 16:00 UT on Friday, 20 March 2015 in preparation for superior solar conjunction. On Tuesday, 24 March, also at 16:00 UT, the STEREO Ahead spacecraft will be reset into a "safe mode" that it will remain in for the next several months until normal operations can be resumed again in July.

The term "superior solar conjunction" is the technical phrase which refers to period when one or the other STEREO spacecraft is on the opposite side of the Sun from Earth. For each spacecraft, there is a period when it is so close to the Sun as seen from Earth that the radio interference from the Sun makes it impossible to communicate at all with the spacecraft. For a few days, it will even be physically blocked by the Sun. Without any possibility of communications, the spacecraft will have to be placed into "safe mode" until contact can be reestablished. Before communications are completely cut off, the spacecraft will start slowly rotating about the axis which points at the Sun. This is done to reduce the load on the reaction wheels which keep the spacecraft pointing stabilized. All the science instruments will be turned off, with the sole exception of the radio instrument SWAVES which will stay on to record beacon mode data on the recorder for eventual playback in November 2015. Technical and safety considerations prevent the other instruments from being on during this time.

02/04/2015 07:00 PM
A Selfie from the Other Side of the Sun.

STEREO-A is now on the other side of the Sun, over 290 million km (180 million miles) away (See Where is STEREO? ). Recently, a new planet has appeared in the field of view of it sun-pointed instruments: Earth. You can see Earth and Mercury in this movie from STEREO Ahead's SECCHI Cor2 coronagraph. The location of the Sun (hidden by a disk so we can see its faint outer atmosphere) is shown with the white circle. The horizontal lines through the two planets are due to saturation effects in the detector - the planets are brighter than the solar features the cameras were designed for.

11/06/2014 07:00 PM
Loss of Contact with STEREO Behind

Communications with the STEREO Behind spacecraft were interrupted on October 1, 2014 immediately after a planned reset of the spacecraft performed as part of a test of solar conjunction operations. The spacecraft telemetry indicated an anomaly in the guidance and control system, but this is still being evaluated. No further communications have been successful since Oct. 1st. Follow this link for more information.

The STEREO Ahead spacecraft has already successfully tested the transition into and out of solar conjunction operations. Actual solar conjunction operations will take place between March 22 and July 14, 2015. STEREO Ahead continues to operate nominally, and is currently providing our only views of the far side of the sun.

Attempts to reestablish communications with the STEREO Behind spacecraft are ongoing.

Launched in 2006, the STEREO mission achieved its prime science goals within the two-year prime mission, but continues to explore solar and heliospheric activity through the current solar maxmimum and beyond.

07/09/2014 07:00 PM
STEREO Entering New Stage of Operations

Since February 2011, the two spacecraft of NASA's STEREO mission have been providing scientists with unprecedented views of the far side of the sun. Placed in orbits that allow their perspective to change over the eight years since their launch in 2006, the satellites are about to enter a new phase of their journey: a time when the bright light and heat of the sun will stand in the way of sending data back to Earth.

07/09/2014 07:00 PM
NASA MESSENGER and STEREO Measurements Open New Window Into High - Energy Processes on the Sun

Understanding the sun from afar isn't easy. How do you figure out what powers solar flares - the intense bursts of radiation coming from the release of magnetic energy associated with sunspots Ð when you must rely on observing only the light and particles that make their way to near-Earth's orbit?

06/26/2014 07:00 PM
NASA's STEREO Maps Much Larger Solar Atmosphere Than Previously Observed

Surrounding the sun is a vast atmosphere of solar particles, through which magnetic fields swarm, solar flares erupt, and gigantic columns of material rise, fall and jostle each other around. Now, using observations from NASA's STEREO, scientists have found that this atmosphere, called the corona, is even larger than previously thought.

06/26/2014 07:00 PM
Panoramic view of particles from the Sun

Time and again, the sun hurls energetic charged particles into space in violent eruptions. At the same time, a continuous stream of particles, the solar wind, escapes from its surface. Numerous space probes in the EarthÕs vicinity monitor how this matter propagates through space. However, until STEREO this information never showed the whole picture.

03/17/2014 07:00 PM
The "Perfect" Solar Storm?

On July 22, 2012, a massive cloud of solar material erupted off the sun's right side, zooming out into space and passing one of NASA's two Solar Terrestrial Observatory (STEREO) spacecraft along the way. Scientists clocked this giant cloud, known as a coronal mass ejection, or CME, as traveling over 3000 kilometers per second as it left the Sun.

11/19/2013 07:00 PM
Four Comets at Once

Four comets are now visible using STEREO-A's HI2, although you'll have to look very closely to see them all.

11/19/2013 07:00 PM
MAVEN is on its way

The MAVEN mission is headed for Mars and will be partnering with STEREO on the way. The MAVEN mission includes solar wind sensors which combined with those of STEREO will provide another vantage point so that we can better understand the 3D structure of our complex space environment. In addition, STEREO keeps an eye on space weather throughout the solar system, providing warnings of danger to MAVEN and other spacecraft far from Earth.

You can follow the progress of MAVEN and STEREO with the STEREO orbit tool by checking off MAVEN at the bottom of the page.

02/13/2013 07:00 PM
STEREO's anticipated observations of Comet ISON

Astronomers are eagerly awaiting the arrival of Comet ISON, which will pass within just 2.7 solar radii from Sun center on November 28, 2013 (U.S. Thanksgiving). Although comets are unpredictable, Comet ISON has the potential to be a major comet. If so, STEREO should have a spectacular view. To assist with planning for this event, a new web page has been put together describing Comet ISON's orbit, and how the comet will be seen by STEREO's telescopes, and those on other solar observatories.

12/20/2012 07:00 PM
Earth now visible in STEREO Behind's Inner Heliospheric Imager

The STEREO Behind spacecraft has now moved far enough in its orbit for Earth to enter the HI1-B field-of-view. Earth has been visible in the HI2 telescopes since launch, but this is the first time it's been visible in either of the HI1 telescopes, which image areas closer to the Sun. This is happening because the STEREO spacecraft are moving closer to the points in their orbits at which they will be directly opposite Earth on the other side of the Sun.

08/14/2012 07:00 PM
NASA STEREO Observes One of the Fastest CMEs On Record

On July 23, 2012, a massive cloud of solar material erupted off the sun's right side, zooming out into space, passing one of NASA's STEREO spacecraft along the way. Using the STEREO data, scientists at NASA's Goddard Space Flight Center in Greenbelt, Md. clocked this giant cloud, known as a coronal mass ejection, or CME, as traveling between 1,800 and 2,200 miles per second as it left the sun.

07/11/2012 07:00 PM
Giant sunspot shoots out intense, X-class solar flare

A massive sunspot region facing Earth - known as 1520 - has unleashed a large solar flare. NOAAÕs Space Weather Prediction Center says the flare is rated an X1.4. This type of flare is considered ÒstrongÓ and can cause a blackout of high frequency radio communication on the sunlit side of Earth for one to two hours.

04/08/2012 07:00 PM

NOVA SAGITTARII 2012 = PNV J17452791-2305213, becomes apparent in STEREO HI1B imager across 20120420-23.

04/08/2012 07:00 PM
SDO and STEREO Spot Something New On the Sun

One day in the fall of 2011, Neil Sheeley, a solar scientist at the Naval Research Laboratory in Washington, D.C., did what he always does Ð look through the daily images of the sun from NASA's Solar Dynamics Observatory (SDO).

But on this day he saw something he'd never noticed before: a pattern of cells with bright centers and dark boundaries occurring in the sun's atmosphere, the corona. These cells looked somewhat like a cell pattern that occurs on the sun's surface -- similar to the bubbles that rise to the top of boiling water -- but it was a surprise to find this pattern higher up in the corona, which is normally dominated by bright loops and dark coronal holes.

03/11/2012 07:00 PM
What is the biggest NASA accomplishment of 2011?

Twin Solar Spacecraft Take First Complete Image of Far Side of Sun

01/03/2012 07:00 PM
Triangular shaped object in STEREO data explained

Some people have noticed a strange triangular or diamond-shape "object" entering the field-of-view of the HI2 telescope on STEREO Behind around December 26, 2011. You can see the feature in question in this movie moving from right-to-left, just above the trapezoidal occulter on the right side of the image, and more clearly in this close-up movie. What is this?

11/03/2011 07:00 PM
A 360 Degree View of an X-class Flare and A CME

The two STEREO spacecraft now sit on opposite sides of the sun providing a view of the latest solar activity for the entire solar system.

10/24/2011 07:00 PM
STEREO Mission Celebrates Five Incredible Years of Science

On October 25, 2006 a Delta II rocket launched from Cape Canaveral carrying two nearly identical spacecraft. Each satellite was one half of a mission entitled Solar TErrestrial RElations Observatory (STEREO) and they were destined to do something never done before - see the entire sun simultaneously.

08/17/2011 07:00 PM
Space Storm Tracked from Sun to Earth

For the first time, a spacecraft far from Earth has turned and watched a solar storm engulf our planet. The movie, released today during a NASA press conference, has galvanized solar physicists, who say it could lead to important advances in space weather forecasting.

04/20/2011 07:00 PM
Scientists see solar outburst in exquisite detail

Combined data from the STEREO and ACE spacecraft are being used to study the structure of a CME in unprecedented detail, showing considerable evolution in the CME's internal structure as it moves from the Sun to Earth.

04/18/2011 07:00 PM
STEREO turns its steady gaze on variable stars

Researchers have discovered 122 new eclipsing binary stars and observed hundreds more variable stars in an innovative survey using NASA's two STEREO solar satellites.

02/05/2011 07:00 PM
STEREO sees the Entire Sun

On February 6, 2011, NASA released the first ever images of the entire Sun, using a combination of STEREO images together with data from the Solar Dynamics Observatory. This never before seen view was made possible by STEREO's unique viewing geometry.

02/01/2011 07:00 PM
Coming Soon - The Entire Sun

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 6, 2011, NASA will reveal the first ever images of the entire sun and discuss the importance of seeing all of our dynamic star.

12/09/2010 07:00 PM

For the first time scientists have used data analysed by the public to make a real-time prediction of a solar storm that should reach Earth on Monday 13 December, thanks to the Solar Stormwatch web project.

The initiative, launched in February by the Royal Observatory, Greenwich (ROG), in partnership with the STFC Rutherford Appleton Laboratory and the Zooniverse citizen science project, makes it possible for anyone with an internet connection to get involved in the latest solar research by helping to spot and track storms as they erupt from the surface of the Sun. These collective measurements enable scientists to forecast the arrival of storms far enough in advance to issue effective pre-emptive warnings for the first time.

The Sun is much more dynamic than it appears to the naked eye. Intense magnetic fields churn and pummel the SunÕs atmosphere and they store enormous amounts of energy that, when released, can hurl billions of tons of material out into space in eruptions called Coronal Mass Ejections (CMEs) Ð or solar storms.

The latest storm identified by the project is predicted to hit Earth at 07.32 GMT on 13 December. Solar storms have the potential to interfere with communication satellites, upset GPS navigation systems and also pose a health risk to astronauts on the International Space Station. In severe cases they can even knock out entire power grids causing widespread disruption here on Earth. On a gentler note, the particles making up a solar storm can produce beautiful displays of the Northern and Southern Lights as they collide with the Earth's upper atmosphere. Scientists are not overly concerned about the effects of the current storm, but the early warning provided by Solar Stormwatch will allow precautionary measures to be put in place.

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09/30/2010 07:00 PM
STEREO Sees the Farside of the Sun, Feb. 2011

Illustration of the positions of the two STEREO spacecraft show that they attain 180 degrees of separation in Feb. 2011, thus allowing the world to see the entire Sun for the first time.

09/23/2010 07:00 PM
STEREO sees Mercury's tail

Scientists from Boston University's Center for Space Physics (CSP) reported the presence of a comet-like tail in images of the planet Mercury taken by STEREO, in a presentation given September 22, 2010 at the European Planetary Science Congress (EPSC) meeting in Rome.

09/21/2010 07:00 PM
Zig-Zagging Solar Storms

Solar researchers have used a novel set of techniques using STEREO data that allow them to watch the acceleration and deflection of coronal mass ejections with unprecedented precision.

08/01/2010 07:00 PM
Coronal Mass Ejection Headed for Earth

On August 1st around 0855 UT, Earth orbiting satellites detected a C3-class solar flare. The origin of the blast was Earth-facing sunspot 1092. C-class solar flares are small (when compared to X and M-class flares) and usually have few noticeable consequences here on Earth besides aurorae. This one has spawned a coronal mass ejection heading in Earth's direction.

06/13/2010 07:00 PM
A 3D Solar Wave

When a coronal mass ejection (CME) erupts from the Sun, movies in extreme ultraviolet light often show enormous waves, spreading over a large area on the solar surface, just as tsunamis travel far from the original seismic event. Now STEREO data have been used to show that these waves are the footprints of giant domes that spread upward into the corona as well as outward across the surface.

04/22/2010 07:00 PM
STEREO spacecraft catch comet diving into Sun

Using instruments aboard NASA's twin STEREO spacecraft, four post-doctoral fellows at UC Berkeley's Space Sciences Laboratory were able to track the comet as it approached the Sun (Mar. 11-12, 2010) and estimate an approximate time and place of impact.

04/22/2010 07:00 PM
Sun Erupts: Epic Blast Seen by NASA Solar Observatory

NASA's new Solar Dynamics Observatory may be getting all the press this week for its retina-searing first pictures of the sun. But two old sun-observing warhorses recently showed they're not quite ready for pasture yet.

03/07/2010 07:00 PM
Solar Story: Understanding the Sun

STEREO featured live and on-line in a new exhibition at the UK National Maritime Museum

03/07/2010 07:00 PM
Solar Storm Watch

Solar scientists need you! Help them spot explosions on the Sun and track them across space to Earth. Your work will give astronauts an early warning if dangerous solar radiation is headed their way. And you could make a new scientific discovery.

01/26/2010 07:00 PM
Wondering what those odd sphere-like features are in recent STEREO EUVI images?

We have investigated, and determined that these are artifacts caused by an interaction between the high compression factors used for the beacon data, and cosmic ray events on the detector. Our discussion of image artifacts has been updated to include this phenomenon. Another factor which has contributed to this issue has been the recent delay in receiving the full resolution images from the spacecraft. This was caused by a server problem at the Deep Space Network, and has now been resolved.

01/18/2010 07:00 PM
STEREO iPhone App

A new free application for iPhones lets you access up-to-date global views of the Sun from STEREO along with solar activity alerts and other features. With this application, you can interactively view the Sun from any angle, and zoom in on features of interest, based on combined images from both STEREO spacecraft.

11/19/2009 07:00 PM
Do Solar Tsunami's Exist?
The twin STEREO spacecraft confirmed their reality in February 2009 when sunspot 11012 unexpectedly erupted. The blast hurled a billion-ton cloud of gas (a coronal mass ejection, or CME) into space and sent a tsunami racing along the sun's surface. STEREO recorded the wave from two positions separated by 90 degrees, giving researchers an unprecedented view of the event.

10/05/2009 07:00 PM
STEREO Captures Sun's Eruption
The twin STEREO spacecraft (called "Behind" and "Ahead" denoting their relative positions in space), now almost 120 degrees apart, captured this large and dramatic prominence eruption over about a 30-hour period between Sept. 26-27, 2009. Prominences, called filaments when they are viewed against the surface of the Sun, are clouds of cooler gas suspended above the Sun’s surface by magnetic forces. This erupting prominence was large enough that both spacecraft were able to observe it for hours on end, one of the first times that has occurred.

07/13/2009 07:00 PM
Gravity wells could provide parking lots for spaceships
Nature has provided five huge rest stops far out in space for the convenience of spacecraft traveling from Earth. Some NASA folks call them "parking lots" in space. They're unusual locations where gravity loses its pull and a spaceship can loiter, rather like a marble at the bottom of a cup, without using a lot of fuel. Three of them are 930,000 miles outside Earth's orbit. One is between the Earth and the sun, and another is hidden on the far side of the sun.

05/14/2009 07:00 PM
May 15,2009 -- Mysterious comets and igniting planets? No, they're mostly just ghosts...
Regular viewers of SOHO and STEREO data are well familiar with the variety of strange artifacts we see in the satellites images sometimes. We see various strange blobs, reflections and streaks, and I frequently get emails about them (which is something I strongly encourage: you learn by asking questions, so ask away!). Of course, all of these things we see in the data are completely explainable when armed with the appropriate knowledge of CCD detectors (like in digital cameras) and instrument optics (telescopes, lenses, etc). So after over 13 years of SOHO/LASCO images, we have seen and explained every weird artefact that has appeared in the data, and occasionally responded to a few popular myths. More recently (October 2006), we launched the STEREO/SECCHI mission and began send back data from that too. As expected, the STEREO/SECCHI 'COR2' telescopes see exactly the same blobs and streaks (dust, cosmic rays, etc) that we see in LASCO. So no explanation needed there. But the Heliospheric Imagers (HI) are a new kind of telescope and with that comes a new set of strange image effects. So what I'm going to do here is address the two most commonly questioned artifacts that we see in the HI images and explain what they are and why we see them.

05/14/2009 07:00 PM
STEREO Spies First Major Activity of Solar Cycle 24
NASA.s Solar Terrestrial Relations Observatory (STEREO) spacecraft has spotted the first major activity of the new solar cycle. On May 5 STEREO-B observed a Type II radio burst and a bright, fast coronal mass ejection (CME) emanating from the far side of the sun. The activity originated in a solar active region that rotated into view from Earth on May 8.

04/13/2009 07:00 PM
NASA'S STEREO spacecraft reveals anatomy of a solar storm in 3-D.
Observations in 3-D from NASA's twin Solar Terrestrial Relations Observatory (STEREO) spacecraft have allowed scientists, for the first time, to reveal the true size and shape of solar explosions known as coronal mass ejections, or CMEs.

04/08/2009 07:00 PM
STEREO-20: Coming soon to a night sky near you!
STEREO's 20th comet has been discovered... and it's a pretty exciting one! Comet C/2009 G1 (STEREO), also known as STEREO-20, was announced earlier today on MPEC 2009-G30. Discovered yesterday by Chinese amateur astronomer Jiangao Ruan, it is a small but relatively bright (~mag 10-11) comet that, unlike most of SOHO and STEREO's comet discoveries, does not belong to any known population or group of objects. This in itself makes it an interesting target, but the most exciting part of this discovery is that it is very likely to be visible from Earth to observers with relatively small telescopes! This may not seem like a particularly big deal, but of the more than 1,600 comets discovered by SOHO, only a very small number have ever been seen from the ground (perhaps most notably C/1998 J1 (SOHO)), and none of STEREO's other nineteen discoveries have been ground-observable at all.

04/08/2009 07:00 PM
STEREO Hunts for Remains of an Ancient Planet near Earth
NASA's twin STEREO probes are entering a mysterious region of space to look for remains of an ancient planet which once orbited the Sun not far from Earth. If they find anything, it could solve a major puzzle--the origin of the Moon. "The name of the planet is Theia," says Mike Kaiser, STEREO project scientist at the Goddard Space Flight Center. "It's a hypothetical world. We've never actually seen it, but some researchers believe it existed 4.5 billion years ago - and that it collided with Earth to form the Moon."

04/08/2009 07:00 PM
Join STEREO and Explore Gravitational "Parking Lots" That May Hold Secret of Moon's Origin
Two places on opposite sides of Earth may hold the secret to how the moon was born. NASA's twin Solar Terrestrial Relations Observatory (STEREO) spacecraft are about to enter these zones, known as the L4 and L5 Lagrangian points, each centered about 93 million miles away along Earth's orbit.

03/30/2009 07:00 PM
Black Rain
Two artists, Ruth Jarman and Joe Gerhardt of Semiconductor Films, have taken STEREO imagery and combined it with sound into a short film which impressed us, and we think you will enjoy. In their own words, "Here we see the HI (Heliospheric Imager) visual data as it tracks interplanetary space for solar wind and CME's (coronal mass ejections) heading towards Earth. Working with STEREO scientists, Semiconductor collected all the HI image data to date, revealing the journey of the satellites from their initial orientation, to their current tracing of the Earth?s orbit around the Sun. Solar wind, CME's, passing planets and comets orbiting the sun can be seen as background stars and the milky way pass by."

03/22/2009 07:00 PM
100 Hours of Astronomy. Around the world in 80 telescopes.

02/18/2009 07:00 PM
Do gravity holes harbour planetary assassins?
THEY are the places gravity forgot. Vast regions of space, millions of kilometres across, in which celestial forces conspire to cancel out gravity and so trap anything that falls into them. They sit in the Earth's orbit, one marching ahead of our planet, the other trailing along behind. Astronomers call them Lagrangian points, or L4 and L5 for short. The best way to think of them, though, is as celestial flypaper.

01/22/2009 07:00 PM
NASA Sees the 'Dark Side' of the Sun
Today, NASA researchers announced an event that will transform our view of the Sun and, in the process, super-charge the field of solar physics for many years to come.

01/21/2009 07:00 PM
January 24, 2009 marks the point at which the two STEREO spacecraft reach 90 degrees separation, a condition known as quadrature. Since the two STEREO spacecraft went into orbit around the Sun at the beginning of 2007, they have been slowly drifting apart from Earth, and from each other. Ahead has been drifting at an average rate of 22 degrees per year in front of Earth, and Behind has been drifting at the same rate in the opposite direction. After two years in solar orbit, the two spacecraft have finally reached quadrature.

12/16/2008 07:00 PM
SECCHI Makes a Fantastic Recovery!
You would think that, after 13-years of historic comet discoveries with SOHO and two years of amazing STEREO/SECCHI observations and discoveries, we had put a check-mark in most of the boxes for comet-related achievements. But last week, Australian comet-hunter Alan Watson helped us with yet another historic achievement, the recovery of a comet! Here's how it unfolded.

12/14/2008 07:00 PM
Solar Flare Surprise
Dec. 15, 2008: Solar flares are the most powerful explosions in the solar system. Packing a punch equal to a hundred million hydrogen bombs, they obliterate everything in their immediate vicinity. Not a single atom should remain intact. At least that's how it's supposed to work. "We've detected a stream of perfectly intact hydrogen atoms shooting out of an X-class solar flare," says Richard Mewaldt of Caltech. "What a surprise! These atoms could be telling us something new about what happens inside flares."

08/18/2008 07:00 PM
No separation anxiety for STEREO
The two STEREO spacecraft (Ahead and Behind) continue to separate, by orbit design, so that they are 66 degrees apart from each other as of August 5, 2008. This allows them to see more and more of the Sun at the same time. The Behind spacecraft can see 31 degrees more of the Sun than can be seen from Earth.

06/03/2008 07:00 PM
Twisting Solar Jets in STEREO

solarjets STEREO has made possibly the first 3D measurements of a solar jet. Jets are columns of super hot plasma (hot ionized gases at over a million degrees) which shoot out from the sun over the course of just a few minutes - this one reached velocities of 300 km/s (650,000 miles/hour). It was over 10,000 kilometers high and nearly half as wide as the Earth.

STEREO observed it from two points of view 11 degrees apart. With these images it could be clearly seen that the jet was twisted. This twist is important. It agrees with models of jets in which they are caused by the twisting of magnetic field lines. Highly twisted magnetic fields eventually become unstable, much like an over-wound spring. When the writhing fields come into contact with nearby untwisted fields that extend into the solar wind, the twist is transferred to those very long field lines. The twist then rapidly leaves the Sun, pushing the plasma outward at high speed.

04/06/2008 07:00 PM
Solar Tsunami - May 19, 2007

The figure shows a sequence of three 195 A difference images obtained by the EUVI instrument on STEREO taken on May 19, 2007. The images show a tsunami blasting through the Sun's atmosphere at millions of kilometers per hour.

03/17/2008 07:00 PM
STEREO: The Sun's Corona Unraveled in 3D
At the largest scale, the Sun's corona (outermost atmosphere) consists of so-called streamers: huge, pointy cones of enhanced density. On a more basic level, everything in the corona is made up of overlapping loops, sometimes with their tops blown indefinitely upward.

02/05/2008 07:00 PM
The Science Gallery launched at TCD with LIGHTWAVE exhibition
Featuring amongs the installations, is the Heliosphere an installation by TCD astrophysics lecturer Dr Peter Gallagher and Anna Hill, which allows you see 3D close-up satellite footage of the surface of the sun taken by NASA and European Space Agency spacecraft. There is is also an opportunity to try out some interactive clothing that will allow you to "feel" solar flares.
View the movie on youtube about this exhibit. STEREO is not mentioned until the end.

01/29/2008 07:00 PM
Celestial tsunamis
U physicists discover powerful radio waves that may lead to spacecraft damage. The culprit? The most powerful radio waves of their kind ever detected in the Belts. The researchers not only discovered the waves but showed that they are capable of accelerating electrons to near the speed of light--which gives the electrons enough energy to knock out computers, pierce spacesuits, and damage the tissues of astronauts--and that they can do it astonishingly fast.

01/16/2008 07:00 PM
What's the Angle?
The two STEREO spacecraft have been slowly separating over most of the mission, so that now they are 44 degrees apart as of Jan. 8, 2008. They will continue to separate as the mission proceeds. So, what does this gain us? Well, for a time we could generate real 3D images and movies of the Sun for the first time. But there is another major advantage to the widening angle.

01/15/2008 07:00 PM
Twin Probes Watch Sun's Fury in 3-D
Astronomers got a new perspective on the sun in April, when NASA's Solar Terrestrial Relations Observatory (STEREO) probes began sending back the first three-dimensional images of our nearest star. NASA built the twin spacecraft to learn more about coronal mass ejections, or CMEs—billion-ton spitballs of electrically charged particles that sporadically fire off from the sun. When CMEs slam into Earth, their electric fields can blow out the circuits of communications satellites or overload regional power grids. "Anything that's electromagnetic can be affected by their charged particles," says NASA astrophysicist Madhulika Guhathakurta, a program scientist for STEREO.

01/01/2008 07:00 PM
Stellar variability studies with STEREO's Heliospheric Imager
STEREO's Heliospheric Imagers are ideally placed for observing stellar variability. The nature of the synoptic observations means that stars can be tracked continuously through the 2 cameras on both spacecraft for up to 180 days. In some cases, it has taken ground based astronomers years to accumulate enough data to study a star's variability.

12/23/2007 07:00 PM
Imaging the Solar Winds as it Sweeps Past Earth
Data from STEREO's SECCHI Heliospheric Imagers have been used to image gusts in the solar wind as they go by the Earth

12/21/2007 07:00 PM
Planet identification in STEREO coronagraph images
We've been getting a lot of questions lately asking what this small round object was that passed through the COR2-Ahead field of view from December 22nd to January 2nd. Hence, we decided to post this to answer everybody's questions. It's the planet Mercury.

10/30/2007 07:00 PM
Video Q&A
Questions with Answers from STEREO Team Members

10/23/2007 07:00 PM
Naked Science - "Solar Force"
This TV show, which prominently features STEREO will be premiering on the National Geographic Channel Oct. 30 at 9:00 ET:
It will replay a number of times after that.

09/30/2007 07:00 PM
NASA Satellite Sees Solar Hurricane Tear Comet Tail Off

NASA's STEREO satellite captured the first images ever of a collision between a solar "hurricane", called a coronal mass ejection (CME), and a comet. The collision caused the complete detachment of the comet's plasma tail. Comets are icy leftovers from the solar system's formation billions of years ago. They usually hang out in the cold, distant regions of the solar system, but occasionally a gravitational tug from a planet, another comet, or even a nearby star sends them into the inner solar system. Once there, the sun's heat and radiation vaporizes gas and dust from the comet, forming its tail. Comets typically have two tails, one made of dust and a fainter one made of electrically conducting gas, called plasma.

09/20/2007 07:00 PM
Path of Totality: The Movie
On March 29, 2006, a NASA-led science expedition, including a number of STEREO team members, traveled to Tripoli and then the Sahara desert to witness and study -- first hand -- a total solar eclipse. This international expedition was an unprecedented collaboration with Libyan scientists and researchers from across the globe. NASA produced a high definition video documentary of the expedition and its interactions with Libya academics and government officials.

09/13/2007 07:00 PM
New Film Opening in Boston Gives First 3D Look at the Sun

NASA's STEREO Mission, the scientists involved and the vital information that they gather and study, is being presented in a new digital 3D film titled "3D Sun." 3D Sun will bring these images to the world in a way that has only been imagined before. 3D Sun opened at the Boston Museum of Science the first week of September.

07/05/2007 07:00 PM
3D Photo Showcase
We invite you to send us your 3D photos so that we can feature them on our web site. The 3D effect is fun to see and we want to show off what our readers have come up with. The photos need to be in the red/cyan anaglyph mode so that all viewers can see them with standard 3D glasses. (We are willing to show Left/Right pairs (in addition to the anaglyphs).

06/06/2007 07:00 PM
Anatomy of a solar storm
Though we can't yet predict such storms, it's only a matter of time. Space-weather forecasters use satellites and ground-based scopes to monitor sunspots for flares and CMEs but can't tell with certainty if or when they will hit Earth. The STEREO satellites will help scientists determine whether a particular storm is headed for us and, hopefully, will give satellite and energy-grid minders enough warning to prepare for a hit.

04/24/2007 07:00 PM
STEREO's Press Clippings
The STEREO 3D Press Conference has received a large amount of media attention. Click here to view all the press clippings.

04/22/2007 07:00 PM
STEREO Ultraviolet 3D Images
The two STEREO spacecraft were launched together in Oct. 2006 from Cape Canaveral. In the following months they were placed in two separate orbits about the Sun - one (the Ahead spacecraft) moving ahead of Earth's orbit, the other (Behind) moving behind Earth's orbit. Both spacecraft are separating from each other and Earth. The spacecraft now have four degrees of separation, enough to provide true 3D images of the Sun and solar storms for the very first time.

04/19/2007 07:00 PM
The Sun in 3D! - Museum List
On April 23, NASA will unveil 3-D images of the sun from NASA's Solar TErrestrial RElations Observatory (STEREO) on the web, television and museums across the country. For first time, scientists will be able to see structures in the Sun's atmosphere in three dimensions.

02/28/2007 07:00 PM
New Solar Images Herald Better Solar Storm Tracking
NASA researchers will be discussing the remarkable imagery from the recently launched STEREO spacecraft. For the first time, scientists are now able to track solar storms from the sun to Earth using the latest images from NASA's twin STEREO spacecraft. Images supporting the telecon will be available at this site on Thursday morning.

02/28/2007 07:00 PM
Solar Eclipse, STEREO Style
On Feb. 25, 2007 there was a transit of the Moon across the face of the Sun - but it could not be seen from Earth. This sight was visible only from the STEREO-B spacecraft in its orbit about the sun, trailing behind the Earth.

01/21/2007 07:00 PM
The "Behind" spacecraft leaves Earth orbit.
Jan. 22, 2007 The "Behind" spacecraft leaves Earth orbit for its orbit about the sun. Now both spacecraft are in thier final sun-centric orbits.

01/19/2007 07:00 PM
Comet McNaught - A First Light Present for STEREO
An instrument on one of the two new STEREO spacecraft captured an unprecedented view of the brightest comet of the last 40 years.

12/19/2006 07:00 PM
STEREO First Light Press Release
NASA's twin Solar Terrestrial Relations Observatories (STEREO) sent back their first images of the sun this week and with them a view into the sun's mounting activity.

12/14/2006 07:00 PM
STEREO Learning Center | Extreme Ultraviolet Images
It is not possible for the human eye to see ultraviolet light directly. Thus, the colors of these images are just ways to represent them so we can see them. To keep the images straight, we assign certain colors to EUVI images taken in particular extreme ultraviolet (EUV) wavelengths, so usually the 195 Å images are in green, the 304 Å images are in orange, etc.

12/14/2006 07:00 PM
STEREO Learning Center | Coronagraph Images
A Coronagraph is an instrument which studies the Sun's outer atmosphere, the corona. From Earth the corona is most easily seen during a total solar eclipse.

10/24/2006 07:00 PM
The twin STEREO spacecraft launched from Cape Canaveral Air Force Station.
The twin STEREO (Solar TErrestrial RElations Observatory) spacecraft were launched Wednesday, October 25th, at 8:52 p.m. EDT on a Delta II 7925-10L rocket from Cape Canaveral Air Force Station in Florida.