Sun blows out another big one, expect aurorae tonight!

By Phil Plait | August 5, 2011 5:00 am

On August 4 at about 04:00 UT, the Sun let loose with another big flare, this one ranking as an M 9.5 or so on the standard flare classification, bigger than the one earlier this week. It also triggered a coronal mass ejection, which means we may get some effects here on Earth.

First, the way-cool video:

[Set the resolution to 720p or 1080p for the best view. Note: In the video title I said this happened on August 3. It did, in my time zone! It was August 4th in Universal Time, however. Sorry about any confusion.]

This is in the far ultraviolet, where energetic events like these show up well. The bright regions are actually sunspots, which are dark to our eye but are pretty glowy in the UV. At 03:57 UT the magnetic field lines in the spot reconnected, starting a cascade that released all the energy they contained. This caused the flare that’s fairly obvious in the video. But you can also see material blasting away from the area, some falling back down. Finally, there are wispy tendrils of material arcing up that fade away.

What you don’t really see here (but SpaceWeather has an animated GIF of it) is that this also sparked a coronal mass ejection (CME), a much larger explosion of energy that blasted roughly a billion tons of subatomic particles away from the Sun at the terrifying speed of nearly 2000 km/sec (1200 miles/sec). The energy involved in an event like this will crush your sense of scale to dust: it’s the equivalent of the detonation of 500 million one-megaton nuclear bombs.

Of course, the 150 million kilometers between us and the Sun is a pretty big buffer. As the CME expands the energy spreads out a lot, and by the time it reaches here it’s much weaker, though still significant. Now, don’t panic: this happens a lot, and generally isn’t too big a deal to us on the ground. This flare and CME were big but not nearly as big as the Sun can put out. However, it is expected this material will hit the Earth’s geomagnetic field sometime today, probably around 14:00 UT (10:00 a.m. Eastern US time). If it does, it will probably spark aurorae at high to medium latitudes. I live in Boulder, so I’ll be out tonight looking for them. You can check the NOAA Solar Weather page to see if you are inside the expected region to see the northern lights from this.

I doubt we’ll see many satellite or cell phone problems from this, though it’s possible. This sunspot (technically named Active Region 1261) still seems pretty agitated, so we may yet see more from it. It’s rotating to the opposite side of the Sun, though, so it most likely won’t do anything to us after this.

… but, as I’ve been pointing out, we’re at the start of the solar cycle. It won’t peak until 2013 or so, and it’s around then we’ll probably see the big fireworks. Again, we probably won’t be affected here on Earth — in 2003 we had some huge events, and we survived — but brownouts and damage to satellites are always possible. I’ll be keeping my eye on all this, and you’ll hear about it as soon as I do.

Related posts:

The Sun lets out a brief flare
The Sun lets loose a huge explosion
STEREO sees an ethereal solar blast
INCREDIBLE solar flare video


Comments (22)

Links to this Post

  1. The Sun! The Sun! « I Am Lhurgoyf | August 5, 2011
  1. Rodrigo Valle

    The sun goblins are just clearing up the throats of their CME cannons. When they turn on the aiming mechanism, we are doomed. Doomed!!

  2. Off-topic sorry, but just a quick reminder to y’all that the Juno spaceprobe to Jupiter is scheduled for launch in 3 hours 5 minutes and 33 seconds from now.

    Click on my name above for the source – and the countdown clock at the Juno website. All is looking good so far. Best wishes and hopes for all those involved in making the Juno mission happen. :-)


    Back on topic again – Wow! Our Sun is sure looking blue there. ūüėČ
    Neat clip – thanks BA. :-)

    @1. Rodrigo Valle : CME cannons? I get the acronymn solar~wise but I’m not sure about your ref. there – does it stand for something else too? Anyhow, talk about heavy artillary! ūüėČ

  3. Kevin

    Phil, one point…

    Are you sure of the times? has the time at 10.00UT.

    Otherwise, I haven’t seen a good auroral display for a few years now, and can’t wait for some good action.

  4. Wendy

    Phil, if it’s hitting us Boulderites around 8am, won’t it be too bright to see much of anything aurora-ish? Any pointers for where to look to see possible lights?

  5. isn‚Äôt too big a deal to us on the ground” One presumes ISS FUBAR asstronaughts will get an up close and personal view, starting inside their eyeballs. When the magnetosphere billows, “what could go wrong?” becomes a rhetorical question. Let’s go to Mars! Radiation is no problem – NASA management secure behind a yard of lead shielding (760 torr of atmosphere and no pair formation) says so.

  6. Tim

    Phil, you say that magnetic field lines reconnected, etc. to generate the blast. Could you explain this more thoroughly? How does the energy for this get stored? Where? What is the mechanism for its release to be triggered, and why is it explosive? Is there some reason why it cascades? I’m sure I’m not the only one who doesn’t understand the physics of this.

  7. Chelsea

    I don’t even try to understand the physics, I’m just trying to understand my camera well enough to take pictures of the pretty sparklies. Let’s see…estimated time 10:00 UT, minus 5 hours for EST plus one for daylight savings time…6:00? Let’s hope they’re right on the “plus or minus 7 hours” on the plus side, and let ’em roll for a few hours. Only glitch here is that the weather forecast is “cloudy starting after midnight”. ARGH!

  8. KC

    It should be noted that the K index for this storm is only expected to be about 7 (on a scale of 0-9). That’s pretty good, so you guys up in NY state, northern Vermont, Maine, Michigan, Minnesota, etc., across to Washington State might be in for a nice show. But for us living in light polluted areas on the 41st parallel and south, we need a storm with a K index of 8 or 9. The last time aurora were widely visible in the continental US was on Oct/Nov 2003 when the K index hit about 8.

  9. Mike

    Great article Phil. Please check this link to wikipedia about the strongest CME recorded and it’s consequenceses if it happened today. I am a HAM operator and I know the effects somewhat. Also check out the Ham Sat that was just launched for the ISS.

  10. Doesn’t it take like 5 days for the solar wind to get to Earth? Why should I expect Auroras tonight and not in three-four days?

  11. @ ^ Richard L : From memory, in light travel time it takes photons eight minutes to go from Sun to Earth. Charged particles don’t go quite that fast – but they’re not too much slower either if I’m not mistaken. Which, of course, I could be but that’s my understanding of it, FWIW.

    BTW. A few minor glitches are delaying Juno‘s launch – still holding at T-4 min. & hold just extended another five min – launch window remains open for another thirty ~ forty odd minutes.

  12. Chelsea

    They showed the launch on CBC t.v. news today, looks like it’s off to a good start. Will be interesting to see the reports when it gets to Jupiter.

    As of this afternoon, reports are that the “solar storm” is in progress. Got all fingers, toes, and a couple other body parts crossed that it holds a few more hours til after darkness falls here, and that the clouds hold off. (Yeah, makes it hard to type in this pretzel pose. ūüėČ )

  13. CRB

    dang, sun, you need some Beano over there? ’cause seriously–pee-yew! *fans air* XD

  14. diogenes

    aurora alert, aurora alert. check out spaceweatherdotcom and google lancaster aurora watch.

  15. Call me slow, but what is the other, off center circle in the gif?

  16. Left_Wing_Fox

    I saw bright whispy clouds around 10:05 PM here in NB Canada. They were shifting too fast for the lack of wind, and were bright while the other clouds in the last glow of evening were silhouetted. “Holy crap” thought I… “I wonder if that’s an aurora?”

    I guess so. :)

  17. diogenes

    @Left_Wing_Fox Congrats! I’m at 53 N and of course it was overcast and raining, as it has been for weeks….

  18. Gary Ansorge

    It’s a good thing Juno has “hardened” electronics(to withstand Jupiters radiation belts), otherwise that CME might play havoc with our new probe,,,

    Gary 7

  19. Another New Brunswicker

    I’d say you’re right Left Wing Fox!

    I saw the northern lights here in Bathurst NB Canada, for the first time in a couple years two nights ago :) Brought the whole family out to confirm that it wasn’t just my eyes playing tricks and now it’s further confirmed!

  20. Tom

    It sparked a good show up in Northern Minnesota for sure. I was at Tettegouche State Park–for what else besides doing an astronomy outreach presentation for park visitors including telescope viewing–and we had just wrapped up when they started very suddenly (about 11:00PM CDT) and grew into very bright green pillars. Not so much in the way of curtains or other colors, though, but still more than I’d ever seen. By 11:30-12:00 they’d waned in activity significant but were still observable as faint variations in brightness across the sky. A very cool sight indeed, and good timing for us to have had our more northerly event then!


    I have read a book in manipuri language i.e. NUMEET KAPPA its meaning is SHOOT THE SUN(STARS)!


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