One solar piece of flare

By Phil Plait | March 26, 2010 7:08 am

The Sun is displaying its individuality — I guess the manager at Chochkies finally got through to it — by showing a nice little flare the other day:


This image, taken by the STEREO spacecraft (for Solar Terrestrial Relations Observatory), shows the Sun in the far ultraviolet, almost at X-ray energies. The bright flare is on the left. The slightly tilted elongated diamond is not real; it’s what happens when an electronic detector gets flooded with light. Detectors like this convert photons of light into electrons, and if too many photons hit it, the electrons leak out and "bloom" into nearby pixels.

Flares happen when the magnetic field lines of the Sun get tangled up. A huge amount of energy is stored in those lines! If the magnetic field gets too entangled, they can suddenly reconnect and release that energy. In my book, I make the analogy to a bunch of bed spring coils all under tension and thrown into a bag. If one snaps back, it hits the others which then snap, and you get a very quick and very violent release of energy. For the Sun, that means a solar flare is released. The one shown here is little, but big ones can release as much as 10% of the Sun’s total energy! They roar out, vast and powerful across the electromagnetic spectrum, from radio waves to gamma rays, and unleash a flood of subatomic particles as well.

If you look to the right of the flare, you’ll see some arcs extending up from the Sun’s surface. Those are also loops of magnetic energy, and a little time after this image was taken they too snapped, releasing a coronal mass ejection; it’s spread out more than a flare, so it’s less intense, but CMEs can blast out huge amounts of energy as well.

Images like this, and more observations by STEREO, help astronomers understand our nearest star better. And this isn’t just academic knowledge: flares and CMEs can damage or even destroy satellites, which represent billions of dollars of assets. The government and private companies take this threat very seriously indeed, of course. Just imagine the number of TPS reports they’d have to fill out!

Image credit: NASA, STEREO

CATEGORIZED UNDER: Astronomy, NASA, Pretty pictures

Comments (28)

  1. Phil, you crack me up. And make me want to watch Office Space again.

    Speaking of solar flares, though: To throw out something fun + nerderific, I recently played around with this cool Galaxy Zoo-like effort called Solar Storm Watch:

    You get to look at pics and video of solar flares in an effort to help solar storm detection. Way cool and fun.

  2. I would file this under “solar farts” :-)

    Seriously though, these are great images; our sun impresses me every time!

  3. xKingx

    You say “10% of the Sun’s total energy”. Now as a longtime follower I’m not used to any anomalies in your posts so I wondered what that 10% actually was. Is that 10% of the energy the Sun produced at that particular point in time?

  4. JJA

    In the second paragraph, did you mean “10% of the Sun’s total energy output during some period?” If each large solar flare really cost the Sun 10% of its total energy, there wouldn’t be much left of it after 20-30 such events.

  5. Martin CT

    It’s hard for lay writers to distinguish between energy and power, but between us scientists, we know the difference… Don’t we? :-)

  6. rob

    JJA- yeah, if there were 20 solar flares, and each used 10% of the sun’s total energy, that would be 200% of the suns’s total energy!

    the sun must be using some pyramid scheme with other stars to keep up it’s energy output.

  7. You can tell the sun is angry because it’s turned green.

    Please, don’t make it angry. We wouldn’t like it when it’s angry.

  8. The bright flare is on the left. The slightly tilted elongated diamond is not real; it’s what happens when an electronic detector gets flooded with light.

    That’s what you’d like us to think. It’s really an alien spaceship using ultraviolet cloaking technology. Where’s Billy Meier?

  9. Phil,

    As someone who works in the Energy industry i’ll just point out my pet peeve and you can tell me to shove off.

    I think you meant “power”.

    Energy is power over time. Its why use the word energy to describe how long a battery will last.

    If you say that the sun released 10% of its energy in a flare, that is like saying I drained my battery down by 10% by turning on that heater for a second. Huge amount of power. did you really mean that the sun can lose 10% of its fuel in one of these flares?

    So do you mean what you wrote, or do you mean that the power output of the sun increases by 10% during a flare (a far easier circumstance for me to comprehend)

  10. Pieter Kok

    rob (#6), you can eject 10% of your energy as many times as you like, because each time the 10% is a little less. After N times, the energy that is left is 0.9N, so if N is 30, there is only about 4% of the original energy left.

    BTW, the movies on the STEREO website are really cool too.

  11. rob

    Pieter (#11)

    just goes to show 5 out of 4 blog posters don’t know math.


  12. Ivan

    I came here to grumble about the energy vs. power thing, but y’all beat me to it.

    (The Mythbusters annoy me in the same way, when they measure the “force” of an impact. Surely they mean the /peak/ force, since force is an instantaneous quantity, and the impulse (integral of force over time, or change in momentum) and impact energy are basically determined by the mass and velocity of the projectile. There was one episode, I think the one about jumping into a garbage dumpster, where they actually showed measurements of impact force over time.)

  13. @Ivan

    I don’t watch MB anymore since I stopped paying for cable. I believe it though. But, people commonly attribute impulse to force in everyday language, so I’m not so sure that’s a bad thing for a show that’s trying to use plain language much of the time. If I say “I forcefully shook the table yelling about the difference between force and impulse.” it’s very different from saying that “I impulsively shook the table yelling about the difference between force and impulse.”

    Same with, “The force of the blast drove us to our knees.” Really, it’s the impulse of the blast since the same force would do very little* if applied gradually over a year, but then no one would know what you’re talking about.

    *See! Right there! I casually mixed up impulse and work, but you still understood what I meant.

  14. Gary Ansorge

    13. Ivan:

    I like to show these “force” differences by how much is applied to a .44 magnum pistol as a 16 gm slug is accelerated out the barrel, (accelerating over about 10 inches) vs the “force” experienced when that slug is decelerated as it strikes the target(the bad guy).

    240 gr (16 g) Bonded JSP 1,500 ft/s (460 m/s) 1,200 ft·lbf (1,600 J)(from Wikipedia).

    I’m pretty sure what Phil was referencing was that the flares would release as much energy during the flare as the entire sun would radiate over its whole surface in the same time frame. There is a lot of energy trapped inside the sun that slowly makes its way up from the core, thru a lot of trapping gas, to the surface, where it is finally radiated away. It takes only 8.5 minutes for a photon from the solar surface to reach earth. That particular photon may have taken a thousand years to make it from the core to the surface.

    If the sun was just a big battery, 10 percent would be a diminishing figure but it’s a thermonuclear generator, so the ten percent is constantly regenerated.

    Simple, isn’t it?

    Gary 7

  15. spillane

    I just can’t find any way I can interpret this “but big ones can release as much as 10% of the Sun’s total energy” as being correct.
    Here’s the situation: the largest solar flares recorded have released about 6.0×10^26 JOULES (that’s total energy). The total luminosity (or power rating) of the sun is about 4.0×10^26 WATTS (that’s Joules per second) (Ok, ok 3.839×10^26 if you’re being picky).
    So what is ACCURATE is that: the largest solar flares can release about 1/10 the total amount of energy that the sun releases in ONE SECOND.
    By way of comparison, the largest flares ever recored on seemingly normal F and G main sequence stars have been 10^2 to 10^7 times larger than the largest recorded solar flares. Flares near or greater than the top of that range have also been recorded from some classes of binary stars. Large flares on “flare stars” (cool K and M dwarfs) may release around 10^27 watts.

  16. Ivan

    @The Chemist

    Yeah, I understand the need for plain language, but it’s never actually very costly to use terminology that’s acceptable to both the layperson and the more knowledgeable folk. It makes me think that the MBs don’t always know exactly what they’re measuring.

    I think they should hire a physics consultant who could add more technical details to the show. They wouldn’t even have to use up much time, just flash a few frames of calculations or whatnot and tell people to pause the video if they’re interested.

    (You probably already know this, but it’s quite possible to watch MB without even owning a TV.)

    @Gary Ansorge

    I think you’re probably right about what Phil meant– i.e., energy output over the time frame of the flare. The peak power output is quite a different thing, and I wouldn’t be too surprised if the peak power of a large flare actually gives an even more impressive comparison.


    RE: Energy/Power business.

    I’m glad to see that I’m not the only nitpicker around here! :-)

  18. Sol

    I don’t like to talk about my flare.

  19. Messier Tidy Upper

    Great image & I had no trouble understanding what was meant. Always presuming *my* understanding of what *you* meant is right which it is – I think. 😉

    Good to see solar activity is picking up again.

    Any news on how this new sunspot cycle is tracking?

    As for the false-colour green Sun, its a different & neat look but not quite as good as seeing our daytime star through a Hydrogen-alpha filter which makes it appear a vivid red! :-)

  20. Suns coloured

    The Sun is at once green (peak wavelength) ..

    … Yellow .. as we imagine we see it usually.

    .. white as it is in space and really usually in our sky (or yellow-white?)

    .. black in case of sunspots by way of contrast only.

    … orange &/or red as we see it at sun-set and sun-rise.

    … &, again, green for the briefest of (micro?)seconds during the green flash phenomenon.

    Of course, in false colour the Sun can be any shade you want.

    See :

    for green flash info & photos.

    BTW. Great image. :-)

  21. Plutonium being from Pluto

    Actually, our Sun will pass all the way along the temperature colour spectrum (blue-white-yellow-orange-red) given enough time. As our Sun evolves off the core hydrogen burning main sequence it becomes an orange & red giant before its outer layers slough away into space and it’s core remains first as the blue-hot central star of a planetary nebula. This stellar remnant then is left an ever cooling white dwarf sliding down the temperature-colour scale : White hot, yellow-hot etc .. all the way along its fade to final black dwarf cinder status over hundreds of trillions of years.

  22. Yes we have about 5 billion years until the Sun turns into a smaller version of Betelgeuse, a red giant. Engulfing the Earth as it expands and destroying all life, boiling away our oceans and ripping away our atmosphere. The planetary nebula it eventually creates could be as fantastic as any we see in space today, so the Sun could ultimitely end up as all the colours of the rainbow !!

    The Sun impresses the hell out of me, 1.3 million Earths could fit in it’s volume, it releases more energy in 1 second than has been used in all of human history, and it’s a whopping 99.86% of all the mass in the solar system !

    But it’s a mere tiddler to some stars out there !

  23. Plutonium being from Pluto

    @24. Betelgeuse Says:

    Yes we have about 5 billion years until the Sun turns into a smaller version of Betelgeuse, a red giant.

    Actually, Betelguese is a red supergiant not a giant like our Sun will become which I guess you were probably meaning but might be potentially unclear from your phrasing.

    Betelgeux (as its also spelt) began life with 15 or more solar masses as a blue-hot O type star & has quickly evolved into all the flavours of *supergiant* (blue-white-yellow-ornage-red) ending up as its current red variety. It will some night soon detonater as a type II supernova leaving a neutron star or black hole “corpse”.

    OTOH, our Sun with, surprise, one solar mass will last 10 billion years on the main-sequence so is halfway through its stellar lifespan and will become an orange giant like Arcturus then a red giant like Mira before going planetary nebula and leaving a white dwarf remnant.

    In a nutshell, the difference with Supergiants vs Giants is that Supergiants are :

    1) Much more dramatic and extreme than the giants by almost any measure you care to name esp. size and luminosity. (Except temperature, that’s the “exception that proves the rule.” Both have similar temp ranges. 😉 )

    2) Fuse elements in their cores that go way beyond what the less massive giants can fuse – not just helium into carbon & oxygen but carbon & oxygen into silicon, sulphur, neon, magnesium, nitrogen , etc .. up to they start to fuse elements into iron ..

    3) At which point they can go supernova leaving behind neutron star and black holes unlike the giants which can only ever end in white dwarfs. Please note that some less massive supergiants may, still end up as white dwarfs. Also note the time-scale is *much* shorter for supergiants evolving and dying than it is for ordinary stars and giants. All the supergiants in our sky tonight were born well after the dinosaurs perished!

    For more details & in-depth discussion see :

    Esp. comment # 41 there onwards.

    Or find out much more via James Kaler’s excellent “Stars” (& star-of-the-week) website :

    “The Sun impresses the hell out of me, 1.3 million Earths could fit in it’s volume, it releases more energy in 1 second than has been used in all of human history, and it’s a whopping 99.86% of all the mass in the solar system ! But it’s a mere tiddler to some stars out there !”

    Very true – the Sun impresses the hell out of me too. Although as a minor quibble, our Sun is actually brighter, more massive and more impressive than most stars which are mainly red dwarfs, orange dwarfs and white dwarfs – 75% or so being red dwarfs and 10 % white with orange dwarfs about another 10% and our Sun being in the top 5% of all – but way below the much rarer much, more massive O-B-A-F varieties which dominate the sky through their intrinsic brightness not numbers!

    Stellar astronomy is one of my favourite areas of astronomy. (Not that you’d guess! 😉 )

    One of my favourites is Eta Carinae –

    Which is a candidate for many things incl. being possibly the brightest star in our galaxy – about five *MILLION* times brighter than our Sun. I have a hard enough time imagining a star twice as bright or even twenty-times as bright like Sirius let alone that which blows me away every time I consider it. :-)

  24. Gary Ansorge

    25. PBFP;

    ,,,and just consider, if the “Big Rip” scenario is accurate, all those smaller stars will still be brightly shining when the universe goes swirling down the drain, in a mere 30 billion years or so.

    What a waste,,,

    (Swirling down the drain is topologically identical with “expanding to infinity”, as in “A mountain is just a hole, turned inside out”).

    GAry 7

  25. Ahh yes, Plutonium being from Pluto…I did not phrase that very well about the Sun being a smaller version of Belelgeuse, a red giant. I meant smaller version being a red giant, rather than a red supergiant like Betelgeuse.

    A nice run through of red giants and supergiants, and also info about the Sun…you obviously know your stuff.

    I actually did an article about Betelgeuse,

    …and Eta Carinae

    Some astronomy facts are literally impossible to imagine, it just amazes me no end…which is why I love it 😉

  26. Plutonian

    @27 Betelgeuse : Fair enough – & me too! :-)

    (Belatedly sorry but still.)

    Ex-Plutonium being from Pluto


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