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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.

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.

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.

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.

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.

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.

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.

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."

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.

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."

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.

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.

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.

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.

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."

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.

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.

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.

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.

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.

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.

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.

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.

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.

Data from STEREO's SECCHI Heliospheric Imagers have been used to image gusts in the solar wind as they go by the Earth

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.

Questions with Answers from STEREO Team Members

This TV show, which prominently features STEREO will be premiering on the National Geographic Channel Oct. 30 at 9:00 ET: http://channel.nationalgeographic.com/channel/ET/daily/20071030.html
It will replay a number of times after that.

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.

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.

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.

The STEREO spacecraft shows average activity on the sun. A close-up view of the top of the sun seen in profile shows thousands of little spurts, like small blow torches, shooting out all over the sun.

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).

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.

The STEREO 3D Press Conference has received a large amount of media attention. Click here to view all the press clippings.

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.

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.

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.

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.

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.

An instrument on one of the two new STEREO spacecraft captured an unprecedented view of the brightest comet of the last 40 years.

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.

View the STEREO first light 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.

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.

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.