I’m sure what I can say about this, except that it’s oddly engaging.
I’ve been to VLA*, many years ago to do a video for an educational activity, and I don’t recall seeing them behave quite this way. Maybe I should’ve waited until night time.
Tip o’ the side lobe to my pal and science nerd Jeri Ryan on Google+.
* Yes, I know the name was recently changed to the Karl G. Jansky Very Large Array, but I’ll be honest: I don’t like the new name. If they had just called it the Jansky Array that’d be fine. But if the old name was clunky, it had an easy acronym. Now the name is longer and the acronym harder! So to me, it’ll always be the VLA. And get off my lawn.
As Cassini weaves its way around the multiple moons of Saturn, it’s not really a coincidence when one gets in the way of another. As a matter of fact, it’s a guarantee. These are called mutual events, and when Cassini dove past Dione, it saw this terrific view of Mimas peeking out from behind it:
Nifty, huh? [Click to encronosenate.]
Dione is nearly 3 times larger than Mimas (1100 versus 400 km wide), but Mimas was also more than 6 times farther away, making Dione loom nearly 20 times larger in this shot. I like how you can’t really see the unlit side of Dione, but Mimas marks it pretty well, sliced in half by the edge of the larger moon.
Funny, too: I was thinking to myself that if Cassini was in position to catch this shot, then it should have also caught Mimas when it was on the other side of Dione, the lit part. Well, seek and ye shall find: I searched the Cassini raw image archive and found it! I put a small version of it here; click to embiggen. You can just barely see a small segment of Saturn’s rings in the lower left corner, too.
Neat! I like it when stuff makes sense. While this alignment is rare to see from Earth — we’re a lot farther away, and the geometry has to be precise — we do see moons transiting across their parent planets, and, far less often moons in front of moons. But what’s rare to us is common to Cassini, with its front row seat to this amazing system of worlds.
I was fooling around with helioviewer.org, watching the flare in different wavelengths of light detected by NASA’s Solar Dynamics observatory, when I switched to 17.1 nanometers — in the far ultraviolet. At that wavelength, the glowing plasma that flows along the Sun’s magnetic field lines is very bright. The images were so beautiful, so incredible, I made a video animation of them, covering the time range of January 26, 2012 at midnight to January 28 at noon (UTC), which includes the huge X2 solar flare that erupted on the 27th. The video shows huge loops of magnetism on the Sun’s surface, glowing plasma flowing along them… and then 48 seconds in the flare changes everything. Watch:
Holy wow! Isn’t that awesome? Make sure you watch in in HD, and make it full screen to get the whole effect.
What you’re seeing is Active Region 1402, a sunspot cluster. This is a tangled collection of magnetic field lines piercing the surface of the Sun. Like a bar magnet, there are two poles to each loop, a north and a south pole. The gas on the surface of the Sun is so hot it has electrons stripped off, so it’s strongly affected by the intense magnetic field, and flows along these towering loops, which can reach heights of 300,000 km (180,000 miles) in this region.
The loops are tied to the plasma, too, and this material is twisting and roiling as it rises and sinks. The lines get tangled, and like a short circuit they can snap and reconnect. When they do, they release vast amounts of energy as a solar flare. In the video you can see the messy, disorganized loops getting more and more tangled up. Then KABLAM! The flare itself is not visible because it happened too quickly to be seen on this timescale (see the video yesterday for that). But you can see the effect on the magnetic field loops! They suddenly become far more organized, tight, and calm.
The Sun is fiendishly complex, and astonishingly beautiful. Clearly, to our brains, these things are connected. Remember, too: this beauty, this magnificence, is brought to you by science. Without our curiosity and our need to understand the Universe better, you would never have been able to watch in awe as superheated plasma arcs dwarfing the Earth itself grew and collapsed on the surface of a star one hundred fifty million kilometers away.
Think of that the next time someone says science takes away the beauty and mystery of life.
Photographer Alistair Chapman traveled to Tromso, Norway — 300 km north of the Arctic Circle — to capture video of the aurorae from the recent spate of solar storms. What he caught on camera is remarkable: shimmering, waving, dancing lights moving in real time!
[Make sure you set it to 720p; Chapman says higher-def footage is coming soon.]
That’s amazing. Aurorae video is generally done with time lapse to show the movement, which is usually slow. I’ve often wondered just how fast the movement really is; I always figured fluctuations in the solar particle density, speed, and magnetic fields would produce real-time changes in the lights, but I’d never seen anything like this! After a search of YouTube I actually found several more.
I know some people will think this is fake, and I had my skeptic hat on while watching it. Note that in most time lapse you can see the stars move; in this they don’t, indicating (unless it’s a complete fake) short periods of time during the filming. Given that, plus the existence of other video like it, I’m thinking this is real.
Mind you, the movement you’re seeing isn’t a physical motion. It’s not like solid curtains of material are flapping. The lights are caused by atoms in the upper atmosphere getting hit by subatomic particles blasted out by the Sun, caught by our Earth’s magnetic field, and funneled down into our air. These particles dump energy into the atoms, moving the electrons up in energy (called excitation). The electrons then jump back down, emitting light in the process (de-excitation). As I said in an earlier post, it’s like needing energy to jump up stairs, but releasing it as you jump down.
Different atoms have different energy levels for the electrons — think of it as more or less spacing vertically between steps in a staircase — so the energy emitted is different, resulting in different colors emitted. That’s why we see green, red, purple… they come mostly from oxygen and nitrogen in the air. So as the magnetic field fluctuates, the particles are sent shooting down in different places, giving the appearance of motion while the atoms themselves don’t move.
The physics is complex and interesting, but the beauty of these lights is, to use another term, magical. Not in the fantasy sense, but in the sense of the emotional response we have to them. They are simply breathtaking in these videos, and are a wonderful by-product of our tempestuous Sun.
Active Region 1402, the same sunspot cluster that blew out a solar flare and caused all the ruckus last week, is still being feisty: just before rotating to the other side of the Sun, it erupted in an intense, pulsing solar flare that actually was much more powerful than the one that happened last Monday. This was an X2 class flare, making it more than twice as energetic as Monday’s.
Happily, the flares were on the edge of the Sun’s disk, so the bulk of the radiation was aimed away from the Earth, but it still makes for some pretty dramatic footage. Using helioviewer.org I created a video showing about 2.3 hours of the Sun as seen by NASA’s Solar Dynamics Observatory. It shows the Sun in the extreme ultraviolet (at a wavelength of 19.3 nanometers if you wanna get geeky), where magnetic activity is seen easily. Watch the upper right corner of our friendly star… and make sure you make it HD and full screen.
Isn’t that awesome? The flare got so bright the automatic software dimmed the rest of the Sun to compensate, giving you an idea of just how powerful these flares can be: at peak, they can give off several percent of the entire Sun’s brightness in one small spot! I love how you can see it pulsing over the course of several minutes; I counted 10 separate flaring events. Each pulse was from a snapping of the Sun’s magnetic field lines, a cascading series created when the first one went off and triggered the rest. And each released mind-numbing amounts of energy — tens of thousands of times our entire planet’s nuclear arsenal combined. Also, you can see the arcing loop around the flare site; that’s plasma trapped in a field line. It erupts outward, but bear in mind the scale: it’s several hundred thousand kilometers across, roughly the distance from the Earth to the Moon, and it blasts away from the Sun like the devil himself is after it.
Like I said: awesome.
You might have noticed the flare looked like an elongated diamond. That’s not real! It’s a digital artifact; what’s happening is the flare got so bright it overwhelmed the pixels in the SDO detector. These collect light like a bucket collects rain. If too much light hits them, they overflow into the neighboring pixel. This flare was so bright it flooded the detector, and created that effect — technically called blooming.
We haven’t seen much of an effect from this flare — just a minor radiation storm that’s at the lowest end of the scale, nothing to worry about — since it wasn’t pointed at us. Had this been in the center of the Sun’s disk, well. That might’ve given me my chance to finally see some aurorae from Colorado. Not this time, though, and sunspots generally don’t last long enough to make it all the way around the Sun again (which takes about 30 days to spin once). But the Sun has a lot of magnetic energy still up its sleeve, and we’ll be seeing more flares like this as we approach the peak of the cycle in 2013 and 2014.
If you live nearly anywhere on Earth — those of you north of 73° you’re out of luck, but I’m guessing there aren’t many of you! — and look to the southeast shortly after sunset, you’ll see the figure of Orion. Follow the three belt stars to the east, and you’ll see a bright star: Sirius, the brightest star in the night sky. If it’s near the horizon, you may see it twinkling madly: flickering, dancing, perhaps even changing color.
This gave astronomer David Lynch an idea: take a time exposure of Sirius with a camera and telephoto, and purposely wiggle the mount. He tried it on January 4, 2012, and the result he got is actually quite lovely:
Isn’t that cool? As the vibrating camera caused the star to trail around, the changing colors got recorded along the track. The changing brightness of Sirius can be seen as well, as parts of the loop-de-loop fade and intensify.
The reason stars twinkle is because of our atmosphere: little blobs of air are constantly in motion. These air parcels act like lenses, and as light passes through them, the path of the ray gets bent a little bit. That’s what causes the dancing motion, the actual twinkling. Different colors get bent by different amounts (which is why prisms break up white light into separate colors).
Yesterday was the weekly live video Space Roundup, run by Fraser Cain from Universe Today. This week we had Pamela Gay, Alan Boyle, Nicole Gugliucci, and Ian O’Neill. We talked about the solar storm, black holes, arsenic life, Newt Gingrich, Phobos-Grunt, and answered some questions from the listeners. Here’s the video:
We do these every week on Google+ at 18:00 UTC on Thursday. Come join us!
Phil Plait, the creator of Bad Astronomy, is an astronomer, lecturer, and author. After ten years working on Hubble Space Telescope and six more working on astronomy education, he struck out on his own as a writer. He's written two books, dozens of magazine articles, and 12 bazillion blog articles. He is a skeptic and fights the abuse of science, but his true love is praising the wonders of real science.
The original BA site (with the Moon Hoax debunking, movie reviews, and all that) can be found here.
Contact me: The Bad Astronomer "at" gmail "dot" com
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