Difference in creation of solar flares and CME?

Difference in creation of solar flares and CME?

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What is the difference in the creation process of solar flares and CME (coronal mass ejections)? How do they relate to sunspots and coronal holes?

Here there are some good explanations about the flares' and CME's differences. But my question focuses on how each of them is created, and what are the respective conditions at the corona.

Edit: In an effort to make the questions more clear, I could add that as far as I can tell both effects result from magnetic reconnection, but in one case we have only energetic particles emitted while in the other we have whole chunks of plasma. Do we know which is the determining factor about which of the two will happen?

Also, I understand that flares are mostly related to sunspots while ejections are to coronal holes. Is this correct? If yes then it sounds like a pretty big difference.

(Please be reminded that specifying that the answer is not known yet is an answer.)

Edit #2: Please see this comment for further clarification of what the question is about.

The point of my comment was that the connection between CMEs and flares would make for a good 20 page research paper in a college course. The connections are still only understood at a kind of cartoon level, after decades of concerted research. But I can tell you what the basic cartoon is, and you can think of that as a kind of operating hypothesis that helps organize many of the observations, but is still a long way from a predictive model. The basic idea is that the energy for flares and for CMEs both seem to come from magnetic free energy stored in the corona due to the magnetic and turbulent nature of the convection zone. The magnetic field is capable of trapping pockets of hot gas that has been energized by this magnetic activity, but then when the field lines get significantly twisted up they reach a point where they can release that energy and relax to a smoother configuration. This relaxation does two things-- it releases energy, and it reconfigures the field such that it can release these pockets of trapped plasma. The former is the solar flare, the latter is the CME, and that's why the two often come together.

However, there seems to be a full range of weak to strong flares, and weak ones would not be associated with CMEs. On top of all that, there may be other processes that heat the corona, and other processes that lead to the solar wind, so one big question is if the heating of the corona is mostly from lots and lots of small flares, and the solar wind is lots and lots of small CMEs, or if the general heating of the corona and general driving of the wind are separate processes from flares and CMEs.

Also, you mention closed and open field regions, so these questions can be asked separately in those two domains. But CMEs would normally come from closed field regions that open up when the field reconfiguration occurs, I believe open field regions tend to be rather sedate and not associated with either strong flares or CMEs, but rather a more steady wind. In the closed field regions, CMEs are often associated with features called "helmet streamers," which are regions of trapped plasma that are kind of combed out at their highest point by the solar wind, creating an interface between closed and open fields that is a good setup for getting field reconfiguration that could launch out some plasma.

Is a solar flare the same thing as a CME?

As Solar Cycle 25, which just began, ramps up, we’re going to be hearing more often about solar flares and coronal mass ejections (CMEs). Both are gigantic explosions of energy on the sun. Sometimes solar flares and CMEs happen at the same time the strongest flares are almost always correlated with CMEs. Both are born when the sun’s magnetic fields explosively realign, driving energy into space. But a solar flare is a brilliant flash of light. A CME is an immense cloud of magnetized particles hurled into space in a particular direction, sometimes toward Earth. As NASA explained:

Solar flares and CMEs … emit different things, they look and travel differently, and they have different effects near planets.

Both eruptions are created when the motion of the sun’s interior contorts its own magnetic fields. Like the sudden release of a twisted rubber band, the magnetic fields explosively realign, driving vast amounts of energy into space. This phenomenon can create a sudden flash of light, a solar flare. Flares can last minutes to hours and they contain tremendous amounts of energy. Traveling at the speed of light, it takes eight minutes for the light from a solar flare to reach Earth. Some of the energy released in the flare also accelerates very high energy particles that can reach Earth in tens of minutes.

The magnetic contortions can also create a different kind of explosion that hurls solar matter into space. These are the coronal mass ejections, also known as CMEs. One can think of the explosions using the physics of a cannon. The flare is like the muzzle flash, which can be seen anywhere in the vicinity. The CME is like the cannonball, propelled forward in a single, preferential direction, this mass ejected from the barrel only affecting a targeted area. This is the CME, an immense cloud of magnetized particles hurled into space. Traveling over a million miles per hour, the hot material called plasma takes up to three days to reach Earth. The differences between the two types of explosions can be seen through solar telescopes, with flares appearing as a bright light and CMEs appearing as enormous fans of gas swelling into space.

While most predictions for Solar Cycle 25 have called for an unusually weak cycle (fewer flares, less activity, than at the peak of other solar cycles), a recent study called for an unusually strong cycle (lots of flares and other activity). Time will tell. Here’s an image of the sun on January 6, 2021. You can see it’s blank no sunspots. According to, the sun has had no visible spots for the past 3 days. But the sun is ramping up in activity and starting to form spots. See photos from EarthSky community members. In 2020, the sun was spotless for a total of 208 days. It’s likely to have fewer spotless days this year. Image via SDO/ HMI/

Flares and CMEs have different effects at Earth as well, which explains the high interest in them among members of the public. NASA explained:

The energy from a flare can disrupt the area of the atmosphere through which radio waves travel. This can lead to degradation and, at worst, temporary blackouts in navigation and communications signals.

On the other hand, CMEs can funnel particles into near-Earth space. A CME can jostle Earth’s magnetic fields, creating currents that drive particles down toward Earth’s poles. When these react with oxygen and nitrogen, they help create the aurora, also known as the Northern and Southern Lights. Additionally, the magnetic changes can affect a variety of human technologies. High frequency radio waves can be degraded: Radios transmit static, and GPS coordinates stray by a few yards. The magnetic oscillations can also create electrical currents in utility grids on Earth that can overload electrical systems when power companies are not prepared.

NASA can point to a robust space-based heliophysics fleet – a fleet of solar, heliospheric, geospace, and planetary spacecraft – that operate simultaneously to understand the dynamics of the solar system and are always on the watch for these explosions. That’ll be important in the coming years as Solar Cycle 25 revs up and creates more activity on the sun: more flares and more CMEs. NASA explained:

Much like how we forecast thunderstorms and rain showers, the U.S. National Oceanic and Atmospheric Administration’s Space Weather Prediction Center runs simulations and can make predictions about when the CME will arrive at Earth based on this and other data. They then alert appropriate groups so that power companies, airlines, and other stakeholders can take precautions in the event of a solar storm. For example, if a strong CME is on its way, utility companies can redirect power loads to protect the grids.

Here’s another image of the sun on January 6, 2021, via NOAA’s Space Weather Prediction Center. If you go to that page, you can get lots of up-to-date info on what the sun is doing today.

Bottom line: Both solar flares and coronal mass ejections (CMEs) are born when the sun’s magnetic fields explosively realign, driving vast amounts of energy into space. A solar flare is a brilliant flash of light. A CME is an immense cloud of magnetized particles hurled into space in a particular direction, sometimes toward Earth.

On the relation between the CMEs and the solar flares

The aim of this paper is to study the relation between the coronal mass ejections, CMEs, and their associated solar flares. During the period from 1996 to 2010 there are 12,433 CMEs recorded by SOHO and 22,688 flare events observed by GOES. Under certain temporal and spatial conditions, we selected 776 CME–Flare associated events. We found that there is a good relation between the solar flare fluxes and their associated CME energies, where R = 65%. In addition we found that 67% of the CME–Flare associated events ejected from the solar surface after the occurrence of the associated flare. Furthermore we found that the CME–Flare relation improved during the period of high solar activity. Finally, we have distributed the selected events depending on their flare class.

Difference in creation of solar flares and CME? - Astronomy

Sunspots are localized regions of extremely intense magnetic fields. These magnetic fields intertwine, and the resulting magnetic energy can generate a sudden, violent release of energy called a solar flare or coronal mass ejections (CMEs).
Solar flares are associated with Coronal Mass Ejections (CMEs) which can ultimately lead to geomagnetic storms.

There is often confusion about the difference between solar flares and coronal mass ejections (CMEs).
The most obvious difference between a solar flare and a CME is the spatial scale on which they occur. Flares are local events as compared to CMEs which are much larger eruptions of the corona.
See Coronal Weather Report: CMEs and Flares | UC Berkeley

A solar flare is an explosion on the Sun that happens when energy stored in twisted magnetic fields (usually above sunspots) is suddenly released. Flares produce a burst of radiation across the electromagnetic spectrum, from radio waves to x-rays and gamma-rays.
Flares are characterized by their brightness in X-rays (X-Ray flux), the GEOS (Geostationary Earth Orbit Satellite) Class

Coronal Mass Ejections (CME) CMEs travel outward from the Sun typically at speeds of about 300 kilometers per second, but can be as slow as 100 kilometers per second or faster than 3000 kilometers per second. The fastest CMEs erupt from large sunspot active regions, powered by the strongest magnetic field concentrations on the Sun. These fast CMEs can reach Earth in as little as 14--17 hours.

A flare is called a coronal mass ejection (CME), an expanding bubble of charged particles that race outward. Flares release energy in many forms - electro-magnetic (Gamma rays and X-rays), energetic particles (protons and electrons), and mass flows. It arrives at earth 18-36 hrs. after leaving the sun. Light and other radiation travels from the Sun to Earth in about 8 minutes.

The Solar and Heliospheric Observatory (SOHO) coronagraphs captured this movie of a coronal mass ejection heading toward Earth on Oct. 22nd 2003.

Aurora, also called the Southern and Northern Lights, are created when the charged solar particles stream down Earth's magnetic field lines and excite oxygen and nitrogen atoms in the atmosphere. Normally the aurora are only visible from places near the poles, like Alaska. But when Earth's magnetic field is overwhelmed, the aurora can dip will into the United States and Europe.

Astronomers rank solar flares into five categories according to the extent to which they emit X-rays. Class X is the most powerful, being tens times the intensity of M-class flares. Flares are characterized by their brightness in X-rays (X-Ray flux), the GEOS Class. The biggest flares are X-Class flares. M-Class flares have a tenth the energy and C-Class flares have a tenth of the X-ray flux seen in M-Class flares.

The sun has an average 11-year cycle of behavior which is projected to peak in 2013.

One on March 6, 1989 knocked out power to the Canadian province of Quebec.

"Forecasters say Solar Max is due in the year 2013. When it arrives, the peak of 11-year sunspot cycle will bring more solar flares, more coronal mass ejections, more geomagnetic storms and more auroras than we have experienced in quite some time.

On the weekend of July 14, 2012, sky watchers around the world got a taste of things to come.

It was mid-Saturday in North America when a coronal mass ejection or "CME" crashed into Earth's magnetic field and triggered the most sustained display of auroras in years. For more than 36 hours, magnetic storms circled Earth's poles. Northern Lights spilled across the Canadian border into the United States as far south as California, Colorado, Kansas, and Arkansas. In the southern hemisphere, skies turned red over Tasmania and New Zealand, while the aurora australis pirouetted around the South Pole."

In 1997, an AT&T Telestar 401 satellite used to broadcast television shows from networks to local affiliates was knocked out during a solar storm. In May 1998 a solar blast disabled PanAmSat's Galaxy IV. Among the casualties: automated teller machines gas station credit card handling services 80 percent of all pagers in the United States news wire service feeds CNN's airport network and some airline weather tracking services.

A space storm also heats the upper level of Earth's atmosphere, causing it to expand. That's no good for satellites that can get caught up in air that didn't used to be there. Communication disruptions can occur without actually damaging satellites. Even cell phone towers can be zapped, causing dropped calls.

The greatest solar storm on record (prior to the Nov. 2003 storm) occurred in 1859, shorting out telegraph wires and starting fires in the United States and Europe. Paal Brekke, SOHO deputy project scientist, told this week's storm, if it hooks up with Earth in just the right way, would be about one-third as strong as the 1859 tempest.

The magnetic orientation of the CME relative to the Earth's magnetic field affects the intensity of the flare.

Flares are characterized by their brightness in X-rays ( X-Ray flux ), the GEOS Class. The biggest flares are X-Class flares . They are major events that can trigger radio blackouts around the whole world and long-lasting radiation storms in the upper atmosphere.
M-Class flares have a tenth the energy. They generally cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow an M-class flare.
C-Class flares have a tenth of the X-ray flux seen in M-Class flares. They have with few noticeable consequences here on Earth.

Answers and Replies

You should try to define what you mean by "deep space". Of course the X-ray content of very strong flares would be damaging to a person in Earth if that person wouldn't be protected by Earth's athmosphere. In fact, communication satellites are damaged when a malign flare occurs. But the X-ray content of solar flares will not affect to a person "in deep space" if "deep space" means for example, a comoving radial distance of 20 Gly

The strongest solar flare ever recorded was rated as X28, and ocurred in 2003

Neutron stars can also produce flares. Neutron star flares are now candidates to mini GRBs

By deep space I mean outside Van Allen belts.

I would like to add one more question: I have heard about the Helen Dodson Prince classification for flares, [Broken]
(botton of the page)

wich can range from 1 to 17. It takes several new features in account if compared with the usual 1-8A W/m2 flux. I´m interested in flares wich might be dangerous to astronauts. Is that classification a good one for that matter? What would be a "malign flare" in that scale?

Difference in creation of solar flares and CME? - Astronomy

Paper Information

Journal Information

International Journal of Astronomy

p-ISSN: 2169-8848 e-ISSN: 2169-8856

Characterizing Coronal Mass Ejections in Solar Cycle Analysis

Ryan Manuel D. Guido, Jason B. Kalaw

Department of Earth and Space Sciences, Rizal Technological University, Mandaluyong City, Philippines

Correspondence to: Ryan Manuel D. Guido, Department of Earth and Space Sciences, Rizal Technological University, Mandaluyong City, Philippines.


Copyright © 2019 The Author(s). Published by Scientific & Academic Publishing.

This work is licensed under the Creative Commons Attribution International License (CC BY).

The Sun is the major source of heat and light in our solar system. Solar activity is associated with several factors including radio flux, solar irradiance, magnetic field, solar flares, coronal mass ejections (CMEs), and solar cycles. This study is unique as it determines the Sun’s activity specifically for the coronal mass ejection, its trend during solar cycle 23 and gives significance to the statistical nature in the form of normality of the emissions of the coronal mass ejections. The data were gathered from the different solar databases to obtain accurate results of the data. A time series analysis was used to measure the CME data for larger cases and to see the apparent difference and trends of the CMEs. This study analyzed the coronal mass ejections in the solar cycle 23 analysis.

Keywords: Solar Cycle Analysis, Coronal Mass Ejections, Solar Activity, Geomagnetic Storms, Solar Physics

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Solar Flares, Prominences, the Solar Wind, and Coronal Mass Ejections
A solar flare is a magnetic storm on the Sun which appears to be a very bright spot and a gaseous surface eruption. Solar flares release huge amounts of high-energy particles and gases and are tremendously hot (from 3.6 million to 24 million °F). They are ejected thousands of miles from the surface of the Sun.

Solar flares were first observed by in 1859 by Lord Richard C. Carrington. He wrote that as he was watching the sun with a telescope, he saw "two patches of intensely bright and white light" near a huge group of sunspots. Just a few seconds later, the flare has disappeared.

It has been recently discovered that solar flares can cause sunquakes. Sunquakes are violent seismic events on the Sun. When a sunquake occurs, energy is released in seismic waves on the relatively fluid surface of the Sun. These waves radiate in concentric circles from the epicenter of the sunquake. These seismic waves seem to be compression waves (perhaps like "P" waves generated by earthquakes). Sunquakes would rate about 11.3 on the Richter scale. These huge quakes release about 40,000 times more energy than the 1906 San Francisco earthquake. Sunquakes were first observed by Alexander G. Kosovichev (Stanford University) and Valentina V. Zharkova (Glasgow Univ., UK).

The solar wind is a continuous stream of ions (electrically charged particles) that are given off by magnetic anomalies on the Sun. The solar wind is emitted where the Sun's magnetic field loops out into space instead of looping back into the Sun. These magnetic anomalies in the Sun's corona are called coronal holes. In X-ray photographs of the Sun, coronal holes are black areas. Coronal holes can last for months or years.

It takes the solar wind about 4.5 days to reach Earth it has a velocity of about 250 miles/sec (400 km/sec). Since the particles are emitted from the Sun as the Sun rotates, the solar wind blows in a pinwheel pattern through the solar system. The solar wind affects the entire Solar System, including buffeting comets' tails away from the Sun, causing auroras on Earth (and some other planets), the disruption of electronic communications on Earth, pushing spacecraft around, etc.

A solar prominence (also known as a filament) is an arc of gas that erupts from the surface of the Sun. Prominences can loop hundreds of thousands of miles into space. Prominences are held above the Sun's surface by strong magnetic fields and can last for many months. At some time in their existence, most prominences will erupt, spewing enormous amounts of solar material into space.

Coronal mass ejections (abbreviated CME's) are huge, balloon-shaped plasma bursts that come from the Sun. As these bursts of solar wind rise above the Sun's corona, they move along the Sun's magnetic field lines and increase in temperature up to tens of millions of degrees. These bursts release up to 220 billion pounds (100 billion kg) of plasma. CME's can disrupt Earth's satellites. CME's usually happen independently, but are sometimes associated with solar flares.

How are solar particle events predicted? And related to flares/CMEs?

I'm new here. I'm a space engineering student and every time I learn something 1000 new questions come to my mind (as usual with science!). Most of my education was from an industrial (practical) point of view, so I feel very, very curious about the science behind the technique. (And I want to be the kind of engineer who understands science rather than applying it blindly). Ok, enough intro, let's go to the question.

What I know: SPEs are mostly protons at several hundred MeV, can cause a dose-equivalent of a few Sv in a matter of hours, but relatively easy to shield. Usually a small storm shelter is designed in a manned spacecraft. The space agency can predict such events, but "how" is not the industry's business :-/ Anyway a radiation detector shall be included in case the prediction fails or communications are impossible.

What I've searched: Read several articles around the internet during my education, now searched the forum before posting and there were several threads. The most useful links I found there are this and this.

What remains unanswered/I'd like to know:

1) How do scientists predict SPEs? Is it magnetic reconnection in the Sun's magnetic field?

2) How do SPEs relate to flares and coronal mass ejections (CME), do they always cause SPEs? Sometimes?

3) How much proton radiation (in Gy or Sv) can a CME cause? Is it small? If not, why was I only taught about SPEs if CMEs are also dangerous? (Also, not sure I fully understand the difference between an SPE and a CME).

Of course, as I'm willing to learn, I will greatly appreciate links to articles for further reading.


Solar energetic particles (SEP) are believed to originate from two different sources, coronal mass ejections (CMEs) and solar flares. In this paper, we have also investigated some statistical properties such as speed, apparent angular width, acceleration, latitude distribution of SEP effective CMEs observed during the period 1996–2016 covering the solar cycle 23 and solar cycle 24. We find that 76% SEP event associated with solar flares originates in the western hemisphere. We also found that SEP associated CMEs are faster and nearly halo in nature. The study shows that mean starting frequency of SEP events associated DH-type II radio burst is 10.9 MHz. We have also investigated the time delay between the flare start/peak time and related SEP, CME and type II burst start time and it is to be found that almost all SEP events occur later than the start time of the flare, CME, m-type II bursts and DH type II radio events.

Difference in creation of solar flares and CME? - Astronomy

I am a senior in high school and I am writing a research paper on solar flares and their effects on airline pilots. I know that the radiation can strongly affect pilots but I don't know how and its very hard to find information about it.

Solar flares produce electromagnetic radiation that reaches the Earth 8 minutes after it is produced. There is radiation over the whole light spectrum, but we are mostly concerned about X-rays and Gamma-rays since they are the most energetic. You also have to know that solar flares are often associated with coronal mass ejections (CME). CMEs result in the ejection of highly energetic protons, electrons and ions.

All of these can cause some trouble for airline pilots. In space, the effect of these particles and radiation could be very harmful, but fortunately airline pilots have a great natural protection: the Earth's magnetic field and atmosphere. The magnetic field protects the Earth from most of the charged particles. But there is a 'hole' in the magnetic field: the lines of the magnetic field go from one pole to the other, therefore charged particles can enter Earth's atmosphere at the poles. So if the pilot flies nearby the pole, he/she will get struck by more of these charged particles. In addition, these charged particles, if incident on the electric systems of the plane, can cause disruptions to on-flight systems.

But you also have to keep in mind that the atmosphere also blocks most of the charged particles, so the higher the plane is flying, the stronger will be the effects.

There are also health issues with that. Recent findings show that there is an increased cancer incidence among airline pilots and cabin crew (mostly skin cancer). But they haven't been able to relate that for sure to cosmic radiation, even though airline pilots and crew have been identified as 'radiation workers'. There are regulations about how much radiation somebody can be exposed to, and for 'radiation workers', this limit is set to about 20-50 times that of the normal public. It is believed that pilots flying at high altitude near the poles receive less than half of this maximal radiation however.

This page was last updated Jan 28, 2019.

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