RSSAll Entries Tagged With: "CME"

GALLERY: Solar blast

A CORONAL MASS EJECTION, or CME, has been spotted erupting away from the Sun, in images taken by the Solar and Heliospheric Observatory (SOHO) spacecraft.

According to the SOHO web site, a CME is a “huge magnetic bubble of plasma that erupts from the Sun’s corona and travels through space at high speed.” Plasma is gas that has been ” heated to sufficiently high temperatures that the atoms ionise”.

When a CME occurs, the plasma shoots out into space and travels through the Solar System. If the timing is right (or wrong, depending on your point of view), a CME can head directly toward Earth.

The first image is a wide field, showing the CME in action on January 14, 2014. The Sun has been blocked out in order to show detail in its outer atmosphere. (The white circle shows the size of the Sun – 1.4 million kilometres, or 870,00 thousand miles, in diameter.) The bright point of light in the top right is the planet Venus. (The white flare on either side of Venus is not real; it is an artifact of the imaging process.)

The second image shows a slightly narrower field, again with the Sun blocked out.

SOHO coronograph image of a CME

A SOHO image of a coronal mass ejection spotted on January 14, 2014. The bright spot in the upper right corner is the planet Venus.

SOHO coronograph image of a CME

Another SOHO view of the January 14, 2014 coronal mass ejection.

SOHO orbits the Sun at a special location between the Sun and the Earth called the L1 Lagrange point. At this location, the gravity of the Sun and Earth balances out, enabling the spacecraft to circle the Sun while always staying on a line between Earth and Sun. It is owned and operated jointly by NASA and the European Space Agency.

Adapted from information issued by NASA and ESA.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Sun sends an explosion our way

SOHO image of a CME

The Solar Heliospheric Observatory spacecraft captured these images of the sun spitting out a coronal mass ejection on March 15, 2013.

ON MARCH 15, the Sun erupted with an Earth-directed coronal mass ejection (CME), a solar phenomenon that can send billions of tonnes of solar particles into space and can reach Earth one to three days later and affect electronic systems in satellites and on the ground.

Experimental NASA research models, based on observations from the Solar Terrestrial Relations Observatory (STEREO) and ESA/NASA’s Solar and Heliospheric Observatory spacecraft, show that the CME left the Sun at speeds of around 14,50 kilometres per second, which is a fairly fast speed for CMEs. Historically, CMEs at this speed have caused mild to moderate effects when they reach Earth.

The NASA research models also show that the CME may pass by the Spitzer (an Earth-orbiting observatory) and Messenger (Mercury orbiter) spacecraft. NASA has notified their mission operators. There is, however, only minor particle radiation associated with this event, which is what would normally concern operators of interplanetary spacecraft since the particles can trip on-board computer electronics.

Earth-directed CMEs can cause a space weather phenomenon called a geomagnetic storm, which occurs when they connect with the outside of the Earth’s magnetic envelope, the magnetosphere, for an extended period of time.

In the past, geomagnetic storms caused by CMEs such as this one have usually been of mild to medium strength.

In the USA, NOAA’s Space Weather Prediction Center is the United States Government official source for space weather forecasts, alerts, watches and warnings.

In Australia, the solar monitoring and notifications are the responsibility of IPS Radio and Space Services.

Adapted from information issued by NASA / GSFC. Image credit: ESA & NASA / SOHO.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Solar storm reaches Earth

Illustration of space weather

Artist's illustration of events on the Sun changing the conditions in Near-Earth space

THIS WEEK SAW A HUGE solar disturbance that sent a storm of energy on a collision course with our planet.

The Sun erupted with one of the largest solar flares of this solar cycle on March 6. The flare was categorised as an X5.4, making it the second largest flare—after an X6.9 on August 9, 2011—since the Sun’s activity moved into a period of relatively low activity called solar minimum in early 2007. The current increase in the number of X-class flares is part of the Sun’s normal 11-year solar cycle, during which activity ramps up to solar maximum, which is expected to peak in late 2013.

About an hour later, the same region let loose an X1.3 class flare. An X1 is 5 times smaller than an X5 flare.

Space weather starts at the Sun. It begins with an eruption such as a huge burst of light and radiation called a solar flare or a gigantic cloud of solar material called a coronal mass ejection (CME). But the effects of those eruptions are felt at Earth, or at least near-Earth space. Scientists monitor several kinds of “space weather” events—geomagnetic storms, solar radiation storms, and radio blackouts—all caused by these immense explosions on the Sun.

Geomagnetic storms

One of the most common forms of space weather, a geomagnetic storm refers to any time Earth’s magnetic environment, the magnetosphere, undergoes sudden and repeated change. This is a time when magnetic fields continually re-align and energy dances quickly from one area to another.

Geomagnetic storms occur when certain types of CMEs connect up with the outside of the magnetosphere for an extended period of time. The solar material in a CME travels with its own set of magnetic fields. If the fields point northward, they align with the magnetosphere’s own fields and the energy and particles simply slide around Earth, causing little change. But if the magnetic fields point southward, in the opposite direction of Earth’s fields, the effects can be dramatic. The Sun’s magnetic fields peel back the outermost layers of Earth’s fields changing the whole shape of the magnetosphere. This is the initial phase of a geomagnetic storm.

The next phase, the main phase, can last hours to days, as charged particles sweeping into the magnetosphere accumulate more energy and more speed. These particles penetrate closer and closer to the planet. During this phase viewers on Earth may see bright aurora at lower latitudes than usual. The increase—and lower altitude—of radiation can also damage satellites travelling around Earth.

The final stage of a geomagnetic storm lasts a few days as the magnetosphere returns to its original state.

The movie below shows the March 6, 2012 X5.4 flare, captured by the Solar Dynamics Observatory (SDO) spacecraft. One of the most dramatic features is the way the entire surface of the Sun seems to ripple with the force of the eruption. This movement comes from something called EIT waves—because they were first discovered with the Extreme ultraviolet Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO).

Since SDO captures images every 12 seconds, it has been able to map the full evolution of these waves and confirm that they can travel across the full breadth of the Sun. The waves move at over a million miles per hour, zipping from one side of the Sun to the other in about an hour. The movie shows two distinct waves. The first seems to spread in all directions; the second is narrower, moving toward the southeast. Such waves are associated with, and perhaps trigger, fast coronal mass ejections, so it is likely that each one is connected to one of the two CMEs that erupted on March 6.

Geomagnetic storms do not always require a CME. Mild storms can also be caused by something called a co-rotating interaction region (CIR). These intense magnetic regions form when high-speed solar winds overtake slower ones, thus creating complicated patterns of fluctuating magnetic fields. These, too, can interact with the edges of Earth’s magnetosphere and create weak to moderate geomagnetic storms.

Geomagnetic storms are measured by ground-based instruments that observe how much the horizontal component of Earth’s magnetic field varies. Based on this measurement, the storms are categorized from G1 (minor) to G5 (extreme). In the most extreme cases transformers in power grids may be damaged, spacecraft operation and satellite tracking can be hindered, high frequency radio propagation and satellite navigation systems can be blocked, and auroras may appear much further south than normal.

Solar radiation storms

A solar radiation storm, which is also sometimes called a solar energetic particle (SEP) event, is much what it sounds like: an intense inflow of radiation from the Sun. Both CMEs and solar flares can carry such radiation, made up of protons and other charged particles. The radiation is blocked by the magnetosphere and atmosphere, so cannot reach humans on Earth. Such a storm could, however, harm humans travelling from Earth to the Moon or Mars, though it has little to no effect on airplane passengers or astronauts within Earth’s magnetosphere. Solar radiation storms can also disturb the regions through which high frequency radio communications travel. Therefore, during a solar radiation storm, airplanes travelling routes near the poles—which cannot use GPS, but rely exclusively on radio communications—may be re-routed.

Photo of an aurora

Aurorae occur primarily near Earth's poles. They are the most common and the only visual result of space weather. This aurora image associated with solar flares and CMEs on February 23-24, 2012 was taken over Muonio, Finland before sunrise on February 27, 2012.

Solar radiation storms are rated on a scale from S1 (minor) to S5 (extreme), determined by how many very energetic, fast solar particles move through a given space in the atmosphere. At their most extreme, solar radiation storms can cause complete high frequency radio blackouts, damage to electronics, memory and imaging systems on satellites, and radiation poisoning to astronauts outside of Earth’s magnetosphere.

Radio blackouts

Radio blackouts occur when the strong, sudden burst of X-rays from a solar flare hits Earth’s atmosphere, jamming both high and low frequency radio signals. The X-rays disturb a layer of Earth’s atmosphere known as the ionosphere, through which radio waves travel. The constant changes in the ionosphere change the paths of the radio waves as they move, thus degrading the information they carry. This affects both high and low frequency radio waves alike. The loss of low frequency radio communication causes GPS measurements to be off by feet to miles, and can also affect the applications that govern satellite positioning.

Radio blackouts are rated on a scale from R1 (minor) to R5 (extreme). The strongest radio blackouts can result in no radio communication and faulty GPS for hours at a time.

More information: Space Weather Frequently Asked Questions

Adapted from information issued by NASA. Images courtesy NASA and Thomas Kast. Video courtesy NASA / GSFC / SDO.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Video – The Sun unleashes its fury

TO US DOWN HERE ON THE GROUND, the Sun seems unchanging and ever-reliable on a day-to-day basis. But satellites reveal the reality to be very different. Our nearest star is actually a boiling, roiling cauldron of hot gases, unseen magnetic fields and titanic explosions.

Those explosions are called coronal mass ejections, or CMEs, and they shoot enormous clouds of particles far out into the Solar System. Sometimes they hit Earth…but fortunately we’re protected by our planet’s strong magnetic field and thick atmosphere.

The Sun produced about a dozen CMEs between November 22 and 28, 2011. The SOHO spacecraft—which monitors the Sun 24/7—spotted them blasting out in different directions. The following video clip comprises over 1,300 frames, and gives us a sped-up view of those eight eventful days on the Sun:

In order to see the CMEs, SOHO had to block out the glare of the Sun using a coronagraph (black circle). A separate instrument took images of the Sun at the same time (superimposed in the middle) so that we could get the best of both worlds.

The next video was produced from images taken with a different Sun-monitoring spacecraft, the Solar Dynamics Observatory. It shows a portion of an extremely long filament (over 1,000,000 km) that was stretched across much of the face of the Sun and gracefully erupted into space (November 14, 2011).

Filaments are cooler gas structures that are tethered to the Sun by magnetic forces. About the upper third of this filament rose up and broke away, but the other two-thirds still remains in sight. The images were taken in extreme ultraviolet light. The clip covers about 12 hours of activity.

Finally, here’s an amazing video that gives us a complete time-lapse of the Sun spanning the entire months of September, October and November 2011 as seen through the SWAP ultraviolet instrument aboard yet another Sun-monitoring satellite, the European Space Agency’s Proba-2 (PRoject for OnBoard Autonomy).

Adapted from information issued by NASA / SDO / ESA.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Killer solar storms? Sorry, not going to happen

THERE’S A LOT OF NONSENSE flying around at the moment about the supposed arrival of a killer solar storm season next year.

As this NASA video points out, there is no expectation that Earth is in any danger. In fact, according to NASA, there “simply isn’t enough energy in the sun to send a killer fireball 93 million miles to destroy Earth.”

Story by Jonathan Nally. Image and video courtesy NASA / GSFC.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Solar flare heads for Earth

SOLAR FLARES ARE GIANT EXPLOSIONS ON THE SUN that send energy, light and high-speed particles into space. These flares are often associated with solar magnetic storms known as coronal mass ejections (CMEs).

The number of solar flares increases approximately every 11 years, and the Sun is currently moving towards another solar maximum, likely in 2013.

That means more flares will be coming, some small and some big enough to send their radiation all the way to Earth.

The biggest flares are known as “X-class flares” based on a classification system that divides solar flares according to their strength. The smallest ones are A-class (near background levels), followed by B, C, M and X.

Overload

Similar to the Richter scale for earthquakes, each letter represents a 10-fold increase in energy output. So an X is ten times an M and 100 times a C. Within each letter class there is a finer scale from 1 to 9.

C-class and smaller flares are too weak to noticeably affect Earth. M-class flares can cause brief radio blackouts at the poles and minor radiation storms that might endanger astronauts.

And then come the X-class flares. Although X is the last letter, there are flares more than 10 times the power of an X1, so X-class flares can go higher than 9.

The most powerful flare measured with modern methods was in 2003, during the last solar maximum, and it was so powerful that it overloaded the sensors measuring it. The sensors cut out at X28.

Here’s a video of that X28 flare:

Satellites at risk

The biggest X-class flares are by far the largest explosions in the Solar System and are awesome to watch. Loops tens of times the size of Earth leap up off the Sun’s surface when the Sun’s magnetic fields cross over each other and reconnect.

In the biggest events, this reconnection process can produce as much energy as a billion hydrogen bombs.

If they’re directed at Earth, such flares and associated CMEs can create long lasting radiation storms that can harm satellites, communications systems, and even ground-based technologies and power grids.

X-class flares on December 5 and December 6, 2006, for example, triggered a CME that interfered with GPS signals being sent to ground-based receivers.

Danger to astronauts

NASA and NOAA (the US National Oceanic and Atmospheric Administration)—as well as the US Air Force Weather Agency (AFWA) and others—keep a constant watch on the Sun to monitor for X-class flares and their associated magnetic storms.

With advance warning many satellites and spacecraft can be protected from the worst effects.

On August 9, 2011 at 3:48am US EDT, the Sun emitted an X6.9 flare, as measured by the NOAA GOES satellite, and aimed at Earth. These gigantic bursts of radiation cannot pass through Earth’s atmosphere to harm humans on the ground, however they can disrupt the atmosphere and disrupt GPS and communications signals.

In this case, it appears the flare is strong enough to potentially cause some radio communication blackouts. It also produced increased solar energetic proton radiation—enough to affect humans in space if they do not protect themselves.

There was also a coronal mass ejection (CME) associated with this flare. CMEs are another solar phenomenon that can send solar particles into space and affect electronic systems in satellites and on Earth. However, this CME is not travelling toward Earth and so no Earth-bound effects are expected.

Here’s a NASA video that shows the power of X-class flares:

Adapted from information issued by NASA.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Two massive solar eruptions

THE SUN BLEW OUT TWO sizeable ‘coronal mass ejections’ that headed in just about opposite directions over about a two-day period (July 24-25, 2011). Both of these were from the far side of the Sun and had no impact on Earth.

A coronal mass ejection, or CME, is a huge magnetic bubble of plasma that erupts from the Sun’s corona (the outermost layer of the solar atmosphere) and travels through space at high speed.

In the video—which has been put together from a series of still images and sped up—the Sun (represented real-size by the white circle) and some additional area around it is blocked out with an occulting disc so that the fainter details in the corona can be seen.

To give you an idea of the size of these CMEs, look at the white circle that represents the Sun and remember that the Sun is 109 times wider than the Earth!

The images were taken by the STEREO (Ahead) spacecraft.

Adapted from information issued by NASA.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Exoplanets have unearthly light shows

Artist's concept of a 'hot Jupiter' planet

Artist's concept of a 'hot Jupiter' planet with two moons and a Sun-like star. The planet is cloaked in brilliant aurorae—100-1000 times brighter than Earth's—triggered by stellar storms.

BEINGS LIVING ON ‘HOT JUPITER’ PLANETS could be treated to a dazzling nightly light show a thousand times better than Earth’s Northern and Southern Lights.

Earth’s aurorae provide a dazzling light show to people living in the polar regions, with shimmering curtains of green and red undulating across the sky like a living creature.

But new research shows that aurorae on ‘hot Jupiter’ planets closely orbiting distant stars could be 100-1000 times brighter than Earthly aurorae. They also would ripple from equator to poles (due to the planet’s proximity to any stellar eruptions), treating the entire planet to an otherworldly spectacle.

“I’d love to get a reservation on a tour to see these aurorae!” said lead author Ofer Cohen, a SHINE-NSF postdoctoral fellow at the Harvard-Smithsonian Centre for Astrophysics (CfA).

Gigantic stellar blasts

Earth’s aurorae are created when energetic particles from the Sun slam into our planet’s magnetic field. The field guides the particles toward the poles, where they smash into Earth’s atmosphere, causing air molecules to glow like a neon sign.

The same process can occur on planets orbiting distant stars, known as exoplanets.

Aurora Australis seen from the International Space Station

The Southern Lights or Aurora Australis seen from the International Space Station on July 14, 2011.

Particularly strong aurorae result when Earth is hit by a coronal mass ejection or CME—a gigantic blast that sends billions of tonnes of solar plasma (electrically charged, hot gas) into the Solar System.

A CME can disrupt Earth’s magnetosphere—the bubble of space protected by Earth’s magnetic field—causing a geomagnetic storm. In 1989, a CME hit Earth with such force that the resulting geomagnetic storm blacked out huge regions of Quebec.

Planets in the firing line

Cohen and his colleagues used computer models to study what would happen if a gas giant planet in a close orbit, just a few million kilometres from its star, were hit by a stellar eruption.

He wanted to learn the effect on the exoplanet’s atmosphere and surrounding magnetosphere.

The alien gas giant would be subjected to extreme forces. In our Solar System, a CME spreads out as it travels through space, so it’s more diffuse once it reaches us.

Aurora planet animation

In this animation, stunning aurorae (pink/purple) ripple around a 'hot Jupiter' planet.

A ‘hot Jupiter’ would feel a stronger and more focused blast, like the difference between being 100 kilometres from an erupting volcano or one kilometre away.

“The impact to the exoplanet would be completely different than what we see in our Solar System, and much more violent,” said co-author Vinay Kashyap of CfA.

Yet despite the extreme forces involved, the exoplanet’s magnetic field would shield its atmosphere from erosion.

Too close for comfort

This work has important implications for the habitability of rocky worlds orbiting distant stars. Since red dwarf stars are the most common stars in our galaxy, astronomers have suggested focusing on them in the search for Earth-like worlds.

However since a red dwarf is cooler than our Sun, a rocky planet would have to orbit very close to the star to be warm enough for water to exist as a liquid. There, it would be subjected to the sort of violent stellar eruptions Cohen and his colleagues studied.

Their future work will examine whether rocky worlds could shield themselves from such eruptions.

Adapted from information issued by the Harvard-Smithsonian Centre for Astrophysics. Images courtesy David A. Aguilar (CfA). Animation produced by Hyperspective Studios.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Stormy Sun

A coronal mass ejection

A huge explosion from the surface of the Sun, known as a coronal mass ejection. (The direct light from the Sun has been blocked out by the black disc; the white circle shows the size of the Sun.)

  • Coronal mass ejection, a huge solar explosion
  • Can expel a billion tonnes of matter
  • Moves at 1.5 million kilometres per hour

Solar storms bombard Earth with a stream of electrons and other charged particles that interact with gases in our atmosphere to generate colourful aurora.

A coronal mass ejection, a large solar storm, can expel a billion tonnes of matter at a 1.5 million kilometres per hour or more.

The strongest solar storms have the potential to interfere with communications, power grids, and satellites. Solar storms happen most frequently when the Sun is in the active phase of its 11-year cycle, called solar maximum.

Though the Sun was expected to be entering solar maximum in 2010, it had been unusually quiet for at least two years. Despite its relative lack of activity, the Sun released a series of four coronal mass ejections between May 22 and May 24, 2010.

The images above and below show one coronal mass ejection on May 23.

Both images were taken by the Solar Terrestrial Relations Observations (STEREO) Ahead spacecraft. The top image is from 20:09:15 Universal Time (UT). STEREO Ahead acquired the other image just over two hours later at 22:24:00 UT.

A coronal mass ejection

In this image taken two hours after the first one, the coronal mass ejection can be seen streaming away from the Sun.

In the top image, a bright mass of charged particles loops from the Sun’s atmosphere. In the second image, the looped mass had expanded and was moving away from the Sun.

See the full-size images here and here (will open in new windows).

The images show only the Sun’s corona, the outermost layer of the atmosphere. A dark disc covers the rest of the Sun, and a white circle represents the Sun’s surface.

When the charged particles from May’s coronal mass ejections reached Earth, they caused no damage, but they did generate sheets of coloured light dancing across polar skies.

NASA images courtesy the Solar Terrestrial Relations Observatory Team. Text adapted from information issued by Holli Riebeek.

Solar explosions held by magnetic “ropes”

A coronal mass ejection on the Sun.

Coronal mass ejections (CMEs) are huge explosions on the surface of the Sun that should billions of tonnes of matter into space.

Over the last century, astronomers have become very aware of how just dynamic the Sun really is. One of the most dramatic manifestations of this is a coronal mass ejection (CME) where billions of tons of matter are thrown into space.

If a CME reaches the Earth it creates inclement ‘space weather’ that can disrupt communications, power grids and the delicate systems on orbiting satellites. This potential damage means there is a keen interest in understanding exactly what triggers a CME outburst.

Now a team of researchers from University College London (UCL) have used data from the Japanese Hinode spacecraft, revealing new details of the formation of an immense magnetic structure that erupted to produce a CME on the December 7, 2007.

An eruption on the Sun known as a coronal mass ejection.

NASA's STEREO space probe saw an eruption on the Sun known as a coronal mass ejection.

Lead researcher Dr Lucie Green will present the team’s results on Monday, April 12, at the Royal Astronomical Society (RAS) National Astronomy Meeting in Glasgow.

The Sun’s behaviour is shaped by the presence of magnetic fields that thread through the solar atmosphere. The magnetic fields may take on different shapes from uniform arches to coherent bundles of field lines known as ‘flux ropes’.

Understanding the exact structure of magnetic fields is a crucial part of the effort to determine how the fields evolve and the role they play in solar eruptions.

In particular, flux ropes are thought to play a vital role in the CME process, having been frequently detected in interplanetary space as CMEs reach the vicinity of the Earth.

The formation of the flux rope requires that significant energy is stored in the solar atmosphere. The rope is expected to remain stable whilst the solar magnetic field in the vicinity holds it down.

But at some point the structure becomes unstable and it erupts to produce a CME. Using data from the Hinode spacecraft Dr Green has shown that a flux rope formed in the solar atmosphere over the 2.5 days that preceded the December 2007 event. Evidence for the flux rope takes the form of S shaped structures which are clearly seen by one of the Hinode instruments, the Extreme-Ultraviolet Imaging Telescope.

The key point to understanding and predicting the formation of CMEs is to know when the flux rope becomes unstable. Combining the observations of the S shaped structure with information on how the magnetic field in the region evolves has enabled Dr Green to work out when this happened.

The work shows that over 30% of the magnetic field of the region had been transformed into the flux rope before it became unstable, three times what has been suggested in theory.

Adapted from information issued by RAS. Images courtesy the STEREO Science Centre / NASA / SOHO.