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Must-see video of the Sun!

THIS TWO-MINUTE VIDEO shows highlights from the Solar Dynamics Observatory’s second year of studying our nearest star. The NASA spacecraft takes continuous imagery at many wavelengths, providing an unprecedented insight into the life and times of the Sun.

Story by Jonathan Nally. Imagery courtesy NASA / Goddard Space Flight Centre Scientific Visualisation Studio

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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.

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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.

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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.

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A year in the Sun

APRIL 21, 2011 MARKED the one-year anniversary of the Solar Dynamics Observatory (SDO) First Light press conference, where NASA revealed the first images taken by the spacecraft.

In the last year, the Sun has gone from its quietest period in years to the activity marking the beginning of solar cycle 24. SDO has captured every moment with a level of detail never-before possible.

The mission has returned unprecedented images of solar flares, eruptions of prominences, and the early stages of coronal mass ejections (CMEs).

In this short video are some of the most beautiful, interesting, and mesmerising events seen by SDO during its first year.

Adapted from information issued by NASA GSFC.

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Solar storm heading our way

Image of the Sun taken on August 1 by NASA’s Solar Dynamics Observatory

Image of the Sun taken on August 1 by NASA’s Solar Dynamics Observatory. The solar eruption can be seen as the dark area in the top right portion of the Sun's disc.

  • Eruption on the Sun last weekend
  • Swarm of charged particles heading toward Earth
  • Stargazers might see aurorae in the night sky

Sky viewers might get to enjoy some spectacular Northern and Southern Lights, or aurorae, Tuesday or Wednesday nights, depending on where you are in the world.

After a long slumber, the Sun is waking up.

On Sunday, the Sun’s surface erupted and blasted tons of plasma (ionised atoms) into interplanetary space. That plasma is headed our way, and when it arrives, it could create a spectacular light show.

“This eruption is directed right at us, and is expected to get here early in the day [US time] on August 4th,” said astronomer Leon Golub of the Harvard-Smithsonian Centre for Astrophysics (CfA). “It’s the first major Earth-directed eruption in quite some time.”

The eruption, called a coronal mass ejection, was caught on camera by NASA’s Solar Dynamics Observatory (SDO), a spacecraft that launched in February. SDO provides better-than-HD quality views of the Sun at a variety of wavelengths.

“We got a beautiful view of this eruption,” said Golub. “And there might be more beautiful views to come, if it triggers aurorae.”

Below is a very short, speeded-up movie from the Solar Dynamics Observatory, showing a 3.5-hour sequence of X-ray images of the Sun taken on Sunday, August 1. In the upper right can be seen a dark filament of plasma erupting outward.

When a coronal mass ejection reaches Earth, it interacts with our planet’s magnetic field, potentially creating a geomagnetic storm. Solar particles stream down the field lines toward Earth’s poles. Those particles collide with atoms of nitrogen and oxygen in the atmosphere, which then glow like miniature neon signs.

Aurorae normally are visible only at high latitudes. However, during a geomagnetic storm aurorae can light up the sky at lower latitudes. Sky watchers in the northern USA and other Northern Hemisphere countries should look toward the north on the evening of August 3rd/4th for rippling “curtains” of green and red light.

For those at far southern latitudes in the Southern Hemisphere, the idea is to look to the south.

“It should be emphasised, however, that there is no guarantee of seeing an aurora,” said Jonathan Nally, editor of space news web site SpaceInfo.com.au. “Most of the time, only those who live at latitudes very far north in the Northern Hemisphere, or very far south in the Southern, have any chance of seeing an aurora.”

Solar cycle

The Sun goes through a regular activity cycle about 11 years long on average. The last solar maximum occurred in 2001. Its latest minimum was particularly weak and long lasting. This eruption is one of the first signs that the Sun is waking up and heading toward another maximum.

Solar storms can other affects than just producing pretty sky shows. Their interaction with Earth’s magnetic field and atmosphere can cause disruption to satellite and long-distance radio communications.

The can also cause disruptions to long pipeline operations and power grids, as these facilities act light giant radio antennae, experiencing power surges that can knock them out of operation.

In 1989, a significant portion of Quebec experienced an hours-long blackout when a major power grid went down in the wake of a solar storm.

This type of things is not expected to occur with Sunday’s storm, as it is a relatively minor one. But in five or six years time, when the Sun will be reaching the maximum of its cycle, it might be a different story.

Sun facts:

  • The Sun is 109 times wider than the Earth
  • Its mass is about 330,000 times that of the Earth
  • The Sun contains just under 99.9% of all the matter in our Solar System (all the planets, asteroids, comets etc, make up the rest)
  • Its surface temperature is 5,500 degrees Celsius
  • But the temperature at the core is 13.6 million degrees Celsius
  • Nuclear reactions in the core convert matter into energy at the rate of over 4 million tonnes per second! Even at that rate, the Sun will live for 10 billion years.
  • The energy released in the core takes tens of thousands years to reach the surface – from there, it travels at the speed of light and only takes just less than 8.5 minutes to reach Earth, 150 million kilometres away. So when we see the Sun, we see it as it was almost 8.5 minutes ago!

Adapted from information issued by the Harvard-Smithsonian Centre for Astrophysics / NASA.

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Below is a very short, speeded-up movie from the Solar Dynamics Observatory, shows a 3.5-hour sequence of X-ray images of the Sun taken on Sunday, August 1. In the upper right can be seen a dark filament of plasma erupting outward.

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.

The Sun in a new light

NASA’s recently launched Solar Dynamics Observatory, or SDO, has returned early images that confirm an unprecedented new capability for scientists to better understand our Sun’s dynamic processes. These solar activities affect everything on Earth.

Some of the images from the spacecraft show never-before-seen detail of material streaming outward and away from sunspots. Others show extreme close-ups of activity on the Sun’s surface.

The spacecraft also has made the first high-resolution measurements of solar flares in a broad range of extreme ultraviolet wavelengths.

“These initial images show a dynamic Sun that I had never seen in more than 40 years of solar research,” said Richard Fisher, director of the Heliophysics Division at NASA Headquarters in Washington.

“SDO will change our understanding of the Sun and its processes, which affect our lives and society. This mission will have a huge impact on science, similar to the impact of the Hubble Space Telescope on modern astrophysics.”

Solar storm watcher

Launched on February 11, 2010, SDO is the most advanced spacecraft ever designed to study the Sun. During its five-year mission, it will examine the Sun’s magnetic field and also provide a better understanding of the role the Sun plays in Earth’s atmospheric chemistry and climate.

A full-disc multi-wavelength extreme ultraviolet image of the Sun taken by SDO

A full-disc multi-wavelength extreme ultraviolet image of the Sun taken by SDO on March 30, 2010. False colours trace different gas temperatures. Reds are relatively cool (~60,000 C); blues and greens are hotter (> 1,000,000 C).

Since launch, engineers have been conducting testing and verification of the spacecraft’s components. Now fully operational, SDO will provide images with clarity 10 times better than high-definition television and will return more comprehensive science data faster than any other solar observing spacecraft.

SDO will determine how the Sun’s magnetic field is generated, structured and converted into violent solar events such as turbulent solar wind, solar flares and coronal mass ejections. These immense clouds of material, when directed toward Earth, can cause large magnetic storms in our planet’s magnetosphere and upper atmosphere.

SDO will provide critical data that will improve the ability to predict these space weather events.

The danger of space weather

Artist's impression of the Solar Dynamics Observatory in Earth orbit

Artist's impression of the Solar Dynamics Observatory in Earth orbit

Space weather has been recognised as a cause of technological problems since the invention of the telegraph in the 19th century. These events produce disturbances in electromagnetic fields on Earth that can induce extreme currents in wires, disrupting power lines and causing widespread blackouts.

Solar storms can interfere with communications between ground controllers, satellites and airplane pilots flying near Earth’s poles. Radio noise from the storms also can disrupt cell phone service.

SDO will send 1.5 terabytes of data back to Earth each day, which is equivalent to a daily download of half a million songs onto an MP3 player. The observatory carries three state-of the-art instruments for conducting solar research.

SDO is the first mission of NASA’s Living with a Star Program, or LWS, and the crown jewel in a fleet of NASA missions that study our Sun and space environment. The goal of LWS is to develop the scientific understanding necessary to address those aspects of the connected Sun-Earth system that directly affect our lives and society.

Adapted from information issued by NASA / SDO / AIA.

The Sun’s stormy surface

An image captured by NASA's SOHO spacecraft shows storms brewing on the Sun.

A flare and a storm brewing on the surface of the Sun.

Magnetic storms from the Sun bombard Earth with charged particles that can interfere with electronics systems and satellites. This image, captured by NASA’s Solar Terrestrial Relations Observatory (STEREO) Ahead spacecraft on February 12, 2010, shows one such storm (albeit a very small one) brewing on the solar surface.

Two active regions glow brightly in this ultraviolet image of the Sun. A small flare rises from the active area on the left. Flares are intense explosions on the Sun that blast radiation into space. This one paints a white line across the left horizon of the Sun.

The active area on the right churns with magnetic loops. Arcs of charged particles rise from the surface and are drawn back down again in the magnetic field. A video showing a sequence of STEREO observations, including this one, reveals that a small coronal mass ejection (CME) burst from this region a short time after this image was taken. Like a flare, a CME sends charged particles and energy into space, but CMEs are larger solar storms that both last longer and carry a larger cloud of particles and magnetic field into space than do flares.

Artist's impression of the twin STEREO Sun-monitoring spacecraft.

Artist's impression of the twin STEREO Sun-monitoring spacecraft.

Both flares and coronal mass ejections can create space weather if aimed at Earth. The charged particles from large storms blast Earth’s magnetic field, which acts as a shield. The charged particles interacting with Earth’s magnetic field generate intense and beautiful aurora, but they can also be destructive. Solar storms in the past have damaged power grids, causing blackouts, and harmed and destroyed satellites.

STEREO is one of several NASA missions studying the Sun. STEREO was launched to help scientists better understand coronal mass ejections. An improved understanding of solar storms will improve space weather forecasts, which will help limit the damage they cause on Earth.

NASA image courtesy the STEREO science team. Text adapted from information issued by the STEREO science team and Holli Riebeek.

Mars is losing its air

Mars

The solar wind is slowly stripping Mars of its atmosphere.

Space physicists from the University of Leicester are part of an international team that has identified the impact of the Sun on Mars’ atmosphere.

Writing in the AGU journal Geophysics Research Letters, the scientists report that Mars is constantly losing part of its atmosphere to space.

The new study shows that pressure from solar wind pulses is a significant contributor to Mars’s atmospheric escape.

The researchers analysed solar wind data and satellite observations that track the flux of heavy ions leaving Mars’s atmosphere. The authors found that Mars’s atmosphere does not drift away at a steady pace; instead, atmospheric escape occurs in bursts.

The researchers related those bursts of atmospheric loss to solar events known as co-rotating interaction regions (CIRs). CIRs form when regions of fast solar wind encounter slower solar wind, creating a high-pressure pulse. When these CIR pulses pass by Mars, they can drive away particles from Mars’s atmosphere.

The authors found that during times when these CIRs occurred, the outflow of atmospheric particles from Mars was about 2.5 times the outflow when these events were not occurring. Furthermore, about one third of the material lost from Mars into space is lost during the impact and passing of CIRs.

The study should help scientists better understand the evolution of Mars’s atmosphere.

Professor Mark Lester, Head of the Department of Physics and Astronomy at the University of Leicester said: “The main reason it happens at Mars and not at Earth is the lack of a magnetic field produced by [Mars]…”. Earth has a strong magnetic field that protects its atmosphere.

“One other aspect of this work is that the observations were made during a very quiet period in the eleven year solar cycle and so we would expect the effect of these and other large scale disturbances to be higher at other times in the solar cycle.”

Adapted from information issued by the University of Leicester.