Coronal mass ejections: what are they?

These balls of plasma are propelled out from the sun at a very high rate of speed.

On August 31, 2012, the sun propelled this coronal mass ejection into space at over 900 miles per second (almost 1,500 kilometers per second). The illustration is merely meant to provide a sense of proportion; the actual distance between the sun and Earth is far greater.
On August 31, 2012, the sun propelled this coronal mass ejection into space at over 900 miles per second (almost 1,500 kilometers per second). The illustration is merely meant to provide a sense of proportion; the actual distance between the sun and Earth is far greater. (Credit for the image goes to NASA)

The energy released during a solar flare causes a vast cloud of electrically charged particles to be ejected from the sun's upper atmosphere, called a coronal mass ejection (CME). These particles are heated to extremely high temperatures and propelled with enormous momentum. Although coronal mass ejections (CMEs) do not pose an immediate danger to life on Earth, they do have the potential to do damage to the technological infrastructure upon which modern society is dependent.

According to Stephanie Yardley, a space weather expert at University College London in the United Kingdom, who was interviewed by Live Science, "CMEs can produce geomagnetic storms upon their arrival in the near-Earth environment." "These produce ground-induced currents that weaken power grids, and they can also affect the accuracy of GPS and GNSS satellite navigation systems," says the article. "These can also have an effect on the precision of the global positioning system."

What are the reasons for CMEs?

CMEs originate from the same process that creates solar flares; they come into existence when a massive loop of the sun's magnetic field, pushing out through the sun's visible surface or photosphere, becomes pinched together near its base then abruptly reconnects at a lower level. This causes solar flares. This process not only causes the release of a tremendous amount of excess energy in the form of high-energy electromagnetic radiation, but it also heats the gases in the area surrounding the reconnection site, sometimes to temperatures of more than 20 million degrees Celsius (36 million degrees Fahrenheit). This provides particles all around the site, including those in the now-isolated loop of the magnetic field above, with a massive boost in speed and energy, which results in the production of a massive bubble of expanding hot gas that breaks free from the sun's gravitational pull and speeds off into space. According to the Space Weather Prediction Center of the National Oceanic and Atmospheric Administration, CMEs can travel at speeds of up to 84 hours on average. Still, they can travel at speeds of up to hundreds of miles per second. The CMEs that travel the fastest and have the most energy may take less than a day to reach Earth's orbit.

CMEs of the corona in the year 2022

Based on the information acquired by software that recognizes images from the so-called LASCO instrument (a spectrometric coronagraph) onboard the SOHO mission, the following is a list of the CMEs released into space by the sun in the year 2022. (Solar and Heliospheric Observatory).

                                                  screen shoot source : www.livescience.com

Storms in the geomagnetic field

When a coronal mass ejection (CME) is aimed at Earth, the repercussions might be rather dramatic. Because the material that is contained in a CME is electrically charged and retains the tangled remnants of the severed magnetic loop, it can dramatically modify the magnetic field that is produced by the magnetosphere, which is located around the Earth.

In a typical scenario, this field is responsible for deflecting the constant stream of particles known as the solar wind as it blows away from the sun. This causes the magnetosphere on the side facing the sun to become more compressed, but on the night side, it creates a long tail known as a magnetotail that extends well beyond the moon's orbit. The vast majority of the solar wind is deflected around the magnetosphere entirely; however, charged particles with specific energies have the potential to become trapped in doughnut-shaped regions known as the Van Allen radiation belts, which are located thousands of miles above the surface of the Earth. Other charged particles are channeled into the atmosphere above the poles. The stunning brilliance of the aurorae, such as the northern lights, is caused by charged particles crashing into gas particles in the high atmosphere of Earth. These collisions energize the molecules in the upper atmosphere, which results in the aurorae.

The arrival of a CME has the potential to upset this delicate balance. The increase in the number of particles that are passing by Earth causes a significant increase in the number of these particles that are directed into the atmosphere above the poles. This results in powerful aurorae that may be seen at considerably lower latitudes. During this time, the magnetosphere is briefly warped due to an increase in pressure within it and interactions with the tangled magnetic fields contained within the CME. This brings the magnetosphere much closer to Earth.

In addition to this, the effect is not limited to being magnetic. Electromagnetic induction is a scientific phenomenon that describes the process by which a changing magnetic field often induces electric currents to flow through materials close to the field. If a CME were to strike our planet, every conductor on Earth, including the globe itself, would be vulnerable to radiation.

This means that currents run through and can wreak havoc on electricity grids and cause navigation systems that rely on satellites to become inoperable.

The Occurrence at Carrington

In 1859, these electrical effects were used to detect the very first geomagnetic storm, which was also the most violent storm ever recorded at the time. In that year, astronomers Richard Carrington and Richard Hodgson from the United Kingdom discovered an eruption in the atmosphere of the sun. It was the first and brightest solar flare that had ever been detected, and immediately after it, a CME arrived and caused magnetic mayhem all over the planet. Strong electric currents were generated due to shifting magnetism around the wires of the recently constructed electric telegraph network. These currents caused pylons to spark, gave telegraph operators shocks, and even allowed for the transmission of messages without using an external power source. According to a report by Wired, at the same time, dazzling aurorae extended all the way down to the tropics, lighting up the night sky so brightly that it was possible to read newspapers.

The Carrington incident was responsible for producing the strongest geomagnetic storm ever recorded. According to Yardley, it arrived at Earth in just 17.5 hours, making it the CME with the quickest travel time ever recorded. "Theoretically, CMEs may have a speed limit of roughly 3000 km/s [6.7 million mph], which is compatible with the energy that is available from the regions of high magnetic fields that produce them," stated the author of the article.

What kind of effects do CMEs have on Earth and astronauts?

According to NASA, the combination of Earth's magnetosphere and atmosphere produces an efficient barrier that deflects and prevents CME particles from reaching the surface of our planet. This is a good development for the life that exists on our planet (opens in new tab). The CME particles' energy is too low to allow them to break through the magnetosphere, even though they are moving at extraordinarily rapid velocities by daily standards. According to a seminal study that was published in 1946 in the journal Terrestrial Magnetism and Atmospheric Electricity, particles that are channeled downwards above the poles can produce aurorae when they collide with sparse gas atoms and molecules at altitudes typically ranging from about 50 to 90 miles (80 to 145 kilometers) above the surface. This process takes place at altitudes that are typically in this range.

According to NASA, astronauts in low-Earth orbit remain well within the magnetosphere and benefit from its shielding effect. The passage of a CME offers a surprising benefit in that its flood of low-energy material briefly provides an extra layer of protection from high-energy cosmic ray particles that are emitted by violent events elsewhere in our galaxy and beyond. This information comes from NASA.

However, the higher-energy particles contained within a CME can pose a major threat to the health of astronauts operating outside the magnetosphere. This could happen, for example, on a future journey to Mars. NASA researchers and engineers are hard at work examining the agency's many potential solutions (opens in new tab) for providing shielding.

Threats posed by technology

Even though CMEs might not pose a significant risk to life directly, human society is significantly more susceptible to the indirect consequences of CMEs due to the enormous technological advancements that have occurred since the Carrington incident. In 2003, for example, a geomagnetic storm that was triggered by the largest solar flare of the modern era disrupted electricity supplies in Sweden and South Africa, while aircraft were rerouted to avoid high-altitude flights over the poles. This event was caused by the largest solar flare of the modern era. According to a report by the Royal Academy of Engineering on solar weather, approximately 47 satellites failed either because of damage caused by radiation or because of static electric charge that accumulated on their surfaces. At the same time, astronauts aboard the International Space Station (ISS) were forced to retreat into the most heavily shielded parts of the station (opens in new tab).

A major solar flare or the energizing particles from a CME can heat Earth's upper atmosphere and cause it to expand significantly. This increases the drag exerted on satellites in orbits close to Earth, which in turn sends them spiraling inwards to re-enter the atmosphere and be consumed by it. Satellites can also have their lifespans shortened differently by solar flares. According to MIT Technology Review, SpaceX was forced to write off more than 40 of its Starlink mini-satellites since their launch coincided with a solar storm in February 2022. MIT Technology Review reported this event.

Can CMEs be anticipated in advance?

A severe geomagnetic storm could impact up to $2 trillion in both immediate damage and knock-on effects, according to an estimate from a report published in 2008 by the National Academy of Sciences (opens in a new tab). It could take the world up to a decade to recover from the effects of such an event. But taking preparations can decrease the effects of a massive CME headed toward Earth, even though there is no way to escape the event entirely. It is possible to secure electrical grids and place satellites into a mode that is safer for them, reducing the likelihood that they will sustain damage that will be permanent.

According to Yardley, "For instance, the [United Kingdom] National Grid is able to lessen the impact on their power systems by turning on as many power lines and high voltage equipment as is humanly possible in order to lessen the burden of excess current running through their system so that they do not become overwhelmed."

Tracking CMEs is essential for many reasons, not the least of which is the ability to prepare for their arrival in various ways in advance. According to Yardley, "after CMEs are spotted, their propagation is predicted to anticipate when they will arrive at Earth." "At this time, our projections of your arrival are accurate within approximately plus or minus 12 hours. However, until they pass over spacecraft extremely close to Earth, it isn't easy to assess their impact (which is determined through the orientation of the magnetic field). This gives us approximately an hour's warning as to whether or not they will be geoeffective.

Additional means at one's disposal

At the Space Weather Prediction Center of the National Oceanographic and Atmospheric Administration, you may stay up to date on the current conditions of both the sun and the auroras of Earth (opens in new tab). After more than 25 years in space, the European Space Agency and NASA Solar and Heliospheric Observatory (SOHO) spacecraft continue to provide real-time updates (opens in new tab) on the sun. The website spaceweatherlive.com (tracks the changing relationship between the sun and Earth as well).

 

 

 

 

 

 

Article source : https://www.livescience.com/what-are-coronal-mass-ejections 

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