Alan Friedman’s photos are no stranger to this blog; I’ve posted a lot of his amazing pictures of the Sun (See Related Posts, below). So many, in fact, that one needs to be surpassingly cool to add to the lineup.
[Click to ensolarnate.]
Yegads. He took this on July 29, 2012. Because the image is inverted – dark things appear bright, and vice-versa – sunspots are intense white patches, bright plages appear dark, and towering filaments are whitish-gray.
Note how the Sun’s face gets darker toward the center and brighter toward the edge – meaning in reality the center is bright and the edge dimmer. This is called limb-darkening (the opposite of limb-brightening seen in some gas clouds), and occurs because gas around the Sun absorbs its light. We look through more of it near the edge than toward the center, so there’s less light coming from the limb of the Sun.
I’ll note that only the face of the Sun is inverted, though. Everything outside that is normal, so the leaping prominences of gas on the edge are bright, as they should be. That might be a bit confusing, but it does make for a dramatic picture.
And given how volatile our local star, you don’t have to go very far to get drama out of it.
Image credit: Alan Friedman
The wonderful astrophotographer César Cantú takes amazing pictures of the sky, and his shots of the Sun are truly cool. On Wednesday, August 8, 2012, he took this image of the Sun and a sunspot called Active Region 1524:
The Sun is a 1970s orange shag carpet!
Actually, César used an Hα filter, which blocks almost all the light from the Sun except for a very narrow slice of color where hydrogen emits light, and in fact this is preferentially given off by hydrogen under the sway of magnetic fields on the Sun, so this image accentuates magnetic activity. You can see lots of structure like the sunspots and the plasma flowing along magnetic fields – especially along the Sun’s edge, where they’re called prominences.
The Sun looks amazingly different depending on how you look at it. Far from being a featureless white disk, it actually has detail all the way down to the resolution of our best telescopes. The surface of the Sun is fiendishly complex, and the amount to understand is equally daunting. And, as usual with astronomy, with this complexity comes astonishing beauty.
Image credit: César Cantú, used with permission.
On August 1, astrophotographer Bart Declercq went outside to get some shots of our nearest star. He used a 30 centimeter (12") telescope, two filters, and a pretty nice camera, he took several thousand frames of video of the Sun. Using a technique that allows combining the frames to get the highest resolution image – and then using a further technique called deconvolution to sharpen it a bit more – he was able to create this tremendous picture of a sunspot:
[Click to ensolarnate and get the 3000 x 2000 pixel hi-res version; this picture displayed here is only one part of a much larger image!]
Wow! This sunspot is officially called Active Region 1532, and is still visible on the Sun’s surface. The detail you can see here is amazing; the spot’s umbra (the dark region) is obvious enough, but the amount of small-scale features in the penumbra (the lighter outer region) is incredible. Surrounding the spot are granules; the pebbly-looking structures which are actually huge convection cells on the Sun. Hot plasma (gas where its atoms are stripped of one or more electrons) from inside the Sun rises to the surface, cools, and sinks back down. Granules are the tops of these convection cells.
Sunspots are where the Sun’s fiercely complex magnetic field breaks through the surface, looping outward and back down, beginning and ending in the spots. These loops of magnetism tend to suppress convection. The plasma cools but cannot sink down. The brightness with which the plasma glows depends on its temperature, so the cooler plasma in the spot appears dark against the hotter material around it.
The scale of all this is hard to grasp. A quick measurement on the image indicates that the spot is about 20,000 kilometers (12,000 miles) across… in other words, just the spot’s umbra alone is roughly the same size as the Earth!
It’s easy to forget just how mighty the Sun is, but pictures like this really slam it home. The Sun is a star, 1.4 million kilometers across, 330,000 times as massive as the Earth, and a complex, amazing, and wondrous place.
Image credit: Bart Declercq
Looking back on it, I should’ve realized friend of the BABlog and masterful solar photographer Alan Friedman would send me a jaw-dropping picture of the vastly ginormous sunspot cluster AR1520 that I wrote about yesterday.
And of course he did:
Holy solar retinopathy! [Click to embiggen.]
This huge cluster of spots is just now coming around the edge of the Sun’s disk, having formed on the far side where we can’t see things directly from Earth. It’s showing up just as the also huge Active Region 1515 is moving around to the Sun’s other side. Since our star takes about 25 days to spin once, these new spots will be visible for another week at least. They may grow in size, and they’ll certainly change shape, and it’s a decent bet they’ll blow off an interesting magnetic storm or two. AR 1515 sure did, and this cluster may be even bigger. Size isn’t a guarantee of activity, but it’s correlated.
Image credit: Alan Friedman, used by permission.
[UPDATE: Oh for criminy’s sake. I made a mistake here. The big sunspot group I describe below is actually AR 1515 which has been on the Sun for a while now. AR 1520 can be seen in the full Sun pic on the very left, on the Sun’s edge! It’s still huge, roughly the same size as 1515, and it’s just now coming into view. Most everything I said below about the sunspot group is correct, except it’s about 1515 and not 1520! I’ve corrected the details below. Sorry about the confusion, and thanks to zAmboni in the comments for pointing this out!]
The Sun is at it again:
Active Region 1520, a vast sunspot group, is currently blemishing the Sun’s face. Active Region 1515, a vast sunspot group, has been blemishing the Sun’s face for days, and is being joined by Active region 1520, another huge group just now coming around the Sun’s edge.
This Solar Dynamics Observatory image shows AR 1515 on the lower right and AR 1520 on the lower left. A quick measurement shows both are about 200,000 kilometers (120,000 miles) across – fifteen times the width of the Earth! If one end were placed on Earth, it would stretch halfway to the Moon.
Having a hard time grasping that? Let me help: here’s the sunspot cluster AR 1515 zoomed in a bit, with the Earth overlaid pretty much to the same scale:
Holy. Crap. The Sun never does anything small, does it?
In fact, this cluster is so flippin’ big you can see it without a telescope! I just went outside and looked using certified eclipse glasses I got for the last solar eclipse. The sunspot cluster was obvious to my naked eye! It’s even easier to see than Venus was during the transit in June.
[WARNING: Listen folks, never look at the Sun without adequate protection. While looking at the Sun won’t necessarily cause permanent or total blindness, it’s not a good idea, and you should NEVER look at the Sun through binoculars or a telescope unless they are outfitted properly. If you don’t know what you’re doing with astronomical equipment, the best bet is don’t do it. If you don’t have eclipse glasses or the right kind of filter, I suggest using binoculars to project the Sun’s image on a piece of paper (noting this can still damage your binoculars). I have notes on viewing something like this safely on my Transit of Venus page. Read that first before trying anything!]
This cluster should be visible over the next ten days or so as the Sun rotates. While AR 1515 will rotate around to the Sun’s far side in a few days, AR 1520 is coming into view now and will be visible for about two weeks. The magnetic field associated with them will be huge as well, so it wouldn’t surprise me if we get some activity in the form of flares from these guys, too. Since I’ll be at Comic Con for several days starting Thursday, I suggest checking SpaceWeather and Universe Today for updates on any solar activity this cluster might unleash. Maybe we’ll get more aurorae!
’tis the season for solar storms, and I’m hearing reports that Active Region 1504 (the same sunspot featured in a dramatic video I posted recently) has been getting feisty, blowing out some flares and causing auroral activity here on Earth.
Photographer Brad Goldpaint was in the right place at the right time Saturday night to see some of this: he went to Crater Lake, Oregon, and at 3:30 a.m. local time on June 17th he took this surpassingly beautiful picture of a somewhat rare event: pink aurorae!
[Click to recombinate.]
Gorgeous! And weird. The colors you see in aurorae depend mostly on what’s in the air. Literally! A solar storm is an eruption of subatomic particles launched from the Sun at high speed. These interact with the Earth’s magnetic field, which, through a complicated process, sends those little beasties down into our air. They slam into the molecules and atoms in the upper atmosphere, blasting off electrons like bullets hitting concrete and sending out shrapnel.
When electrons recombine with the atoms and molecules, a little bit of energy is released in the form of light, and the color of that light depends on what’s doing the emitting. Oxygen atoms, for example, tend to glow green and/or red. Oxygen molecules (two atoms combined, like the kind we breathe) glow blue. Nitrogen molecules can glow either red or blue. Here’s a diagram from the excellent Atmospheric Optics website:
Yesterday, I linked to a picture taken a few days ago by Alan Friedman that showed the sunspots that are currently blowing their lids with flares. He just sent me a new shot, taken yesterday, and… well. It’s stunning. Presenting the sunspot cluster Active Region 1302:
Wow. [Click to ensolarnate.]
It’s hard to imagine just how enormous this cluster is. So to help, I cropped out the big spot on the left and put the Earth to scale next to it.
So yeah. That’s our whole planet.
Sunspots are big.
In fact, these guys are so big I tried to get a picture myself using binoculars, projecting the image onto a white board. Unfortunately, I couldn’t get my set up to work well and all the pictures were out of focus. You might want to try it yourself, but be warned: the bright Sun can damage optics, so you might fry your binocs. Also, of course: NEVER LOOK AT THE SUN. Not with your eyes, not through a telescope, not through binoculars. There are ways to do that, but it takes specialized equipment, and it’s not worth the risk if you don’t know what you’re doing. The Stanford Solar Center has some advice about all this.
Anyway, I expect we’ll see more activity out of these spots over the next few days. Should be a fun ride.
Today, June 21, 2001, at 17:16 UTC (1:16 p.m. Eastern US time), the Sun will reach its peak in its northward travels this year. This moment is the summer solstice — I describe this in detail in an earlier post. Technically, that article is for the winter solstice, but the idea’s the same. Just replace "winter" with "summer" and "December" with "June" and "south" with "north". That should be clear enough. It might be easier just to multiply the entire article by -1. Or stand on your head.
Since for the majority of people on the planet this day marks the start (or more commonly the midpoint) of summer, enjoy the gallery below that shows our nearest star doing what it does best: giving us light, giving us beauty, and sometimes, blowing its top.
Use the thumbnails and arrows to browse, and click on the images to go through to blog posts with more details and descriptions.
The sunspot that erupted on the 13th, producing an M-class flare (medium to strong), has blown its top again: around 02:00 UT last night it produced a bigger, X-class flare! We’re not in any danger from this, but it’s pretty cool:
I think the location of sunspot 1158 is obvious enough. This is an image from the Solar Dynamics Observatory (which just celebrated its first anniversary) when the flare was peaking. It shows the Sun in the far ultra-violet (and is color-coded as green), where energetic events are more obvious. You can see some other active magnetic regions, too. None of those has produced any flares.
You can read all about how this works in my previous post. While this was a stronger flare — it was an X2 class, making it about 3 times more powerful than the flare from the other day — again, we’re in no real danger from it. But if you live in the extreme north or south you should watch for aurorae over the next couple of nights!
Astronomers keep an eye on these events, and if there is any threat to satellites or astronauts they issue an alert. The Sun is capable of producing flares 20 times more powerful than this one at least (in 2003 we saw a few), and those are enough to do some actual harm to space-based assets. As the Sun gets more tempestuous over the next couple of years, scientists will be watching it very carefully.
Tip o’ the lead shielding to Chris Pirillo. Image credit: NASA/SDO
Never forget: the Sun is a star, a mighty ball of ionized gas, and when a star throws a tantrum, even a small one is epic.
And the Sun just sent us a little reminder: NASA’s Solar Dynamics Observatory caught this amazing sequence of a sunspot blasting out a flare, then shooting out a long streamer of plasma:
Wow! So what are we seeing here?
SDO views the Sun in many wavelengths, and in this case we’re looking at ultraviolet light form the Sun so energetic it’s almost X-rays. The bright spot is actually a sunspot! They’re dark in the kind of light we see with our eyes* but can be very bright at other wavelengths. Sunspots are regions of intense magnetic field concentration; magnetic loops arc out of the spot, reach into space, then head back down. They seethe with vast amounts of energy, which can be released explosively under some conditions.
That’s what happened here. Read More