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.

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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:

[Direct link to YouTube video here]

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. (more…)

I keep thinking there’s nothing new under the Sun– or on it. With SOHO, and SDO, and a thousand other telescopes pointed at it, it would take something pretty freaking cool to surprise me.

Well then. Surprise!

Holy solar retinopathy! That’s the Sun?

Yup. But this is not a space-based image from some bazillion dollar observatory! This phenomenal picture was taken by astrophotographer Alan Friedman with this relatively small (but very, very nice) ‘scope. He shot it on October 20th, and it shows our nearest star in the light of hydrogen, specifically what astronomers call Hα (H-alpha). I’ll get to that in a sec…

In this picture you can see sunspots, giant convection cells, and the gas that follows magnetic loops piercing the Sun’s surface. When we see them against the Sun’s surface they’re called filaments, and when they arc against the background sky on the edge of the Sun’s disk they’re called prominences.

The image he took is amazingly high-resolution! He has two closeups, one of the filament and sunspot near the edge of the disk on the left, and the other of prominences leaping up off the edge and silhouetted against the sky:

(more…)

The Sun is getting back into the swing of things: a big active region on its limb erupted yesterday (October 10), sending out a small storm of subatomic particles into space. We weren’t in the line of fire, but over the next few days the rotation of the Sun will bring Active Region 11112 closer to the center of the Sun’s disk, and if that region erupts it may send a storm our way.

Here’s a recent image of the Sun from the Solar Dynamics Observatory:

This shows the Sun in ultraviolet (where activity can manifest itself) from around 23:00 UT (19:00 Eastern US time) on October 11. The active region is pretty obvious there to the lower left.

A magnetogram, which shows magnetic activity, makes the region obvious as well. A recent one (shown here on the left) from around the same time as the image above again shows the active region has a lot of magnetic activity going on.

The Sun’s magnetic field lines can contain a huge amount of energy. As the gas in the Sun roils and swirls, the field lines get tangled together. If they connect, bang! They can explode, sending that energy out into space. (more…)

After a very long absence, it looks like the Sun may finally be kick-starting its magnetic cycle. A big ol’ group of sunspots has just appeared on our nearest star:

A quick comparison to the Sun’s disk (done with Photoshop, so don’t quote me extensively!) indicates this group of spots is about 10 times the width of the Earth, making it decently hefty. It’s the biggest group we’ve seen since the solar minimum a couple of years ago.

The Sun’s face has been almost entirely devoid of spots for some time, and it’s been getting a little weird. There was some activity earlier this year, but it didn’t seem to be gaining any footing. And while this new group of spots doesn’t mean the new solar cycle has finally gotten started, it’s a good sign.

As a quick refresher: the Sun is a variable star. Its magnetic activity strengthens and weakens over a roughly 22 year cycle. It’s actually two 11 year cycles: the field rises in strength over 5 or so years, peaks, then dips back down over the next 5 or so years. When it begins to rise again, the polarity (north/south) is reversed. To be clear, it’s not the actual spin of the Sun that flips, just the magnetic field poles. Also, it’s not exactly 5.5 years every time; the length of the cycle itself can change a bit.

When the Sun’s magnetic field is at its strongest, we see lots of sunspots, which are areas on the surface of the Sun where the local magnetic field lines constrain the movement of the Sun’s gas. The gas cools and dims, looking dark against the hotter gas. Normally, convection (like boiling water) would drag the cooler material down into the Sun’s interior, but the magnetic field prevents that, so sunspots can persist for days or weeks.

Mind you, it’s all far more complicated than this, but hopefully this gives you the idea.

Right now we’re at the minimum of the Sun’s magnetic cycle, and normally we would have seen a rise in magnetic activity more than year ago. But for some unknown reason the Sun has been slow to return to its usual business. No one is really sure what would happen if the minimum were prolonged for years, though there is a weak tie between sunspot activity and the Earth’s temperature (and no, not enough to account for global climate change).

In the face of all these unknowns, I’ll be honest and say I’d like to see the Sun getting back on the stick and producing spots again! So this new grouping is a tentative relief. Hopefully we’ll be seeing more spots soon.

Also, I’ll note that this grouping comes just a few days after a nice filament erupted from the Sun, as seen here by the STEREO spacecraft.

You can monitor the Sun in real time by going to the SOHO spacecraft website, where they frequently update pictures from the solar observatory.

Image credits: STEREO, SOHO, NASA/ESA