Alan Friedman is a photographer who takes amazing pictures of the Sun. While others were out celebrating Cinco de Mayo this past weekend, he was outside taking another jaw-dropping image of the nearest star in the Universe:

Yegads! Click to ensolarnate, and he has a greyscale version, too.

I love the detail and texture of his images. He has an excellent telescopic setup which yields the superb resolution, and he employs an old trick to get the texture: he inverts the image of the Sun’s disk, making black stuff look white and vice-versa. This is a technique that’s been used by astronomers for decades to enhance images; our eyes see details better that way. When Alan does it, I swear it makes the Sun look like a 1.4 million-kilometer-wide shag rug.

All the way on the left, just on the Sun’s edge, you can see a group of sunspots just rotating into view. That’s Active Region 1476, and Alan provided me with a clear picture of them (no tom-foolery) which I’ve put here. That monster group is about 100,000 kilometers (60,000 miles) across, so when I saw them I immediately suspected trouble.

… and sure enough, they had a medium-sized eruption just this morning. At 13:00 UTC they blasted off an M1.4 class flare; big enough to potentially cause some radio disruption and maybe some aurorae. NASA’s Solar Dynamics Observatory got a dramatic view of the eruption:

Flares this size are relatively common; there was one in late March for example. Bigger ones happen less frequently, though again we did see one 50 times this powerful in March as well! We’ll have to see if today’s eruption will cause any aurorae, and either way, we should keep our eyes on AR1476.

Image credit: Alan Friedman, used by permission. Tip o’ the Sun visor to Camilla Corona SDO on Google+ for the video.

I have got to get to Norway. Last year, on September 25, 2011 from Ifjord, Finnmark, Norway, photographer Tommy Eliassen took this jaw-dropping photo of the night sky:

[Click to enstupefyenate.]

I know, seriously, right?

The northern lights play along the right while the Milky Way itself hangs vertically next to it; parallel structures seemingly adjacent but separated by thousands of trillions of kilometers…

And to top it off, a meteor plinks across the sky between them. Meteors burn up about 100 km or so above our planet’s surface, which is at just about the same altitude that’s the lower limit of green aurorae. Amazingly, that meteor is probably the closest thing you can see in this picture above the clouds^*.

You can see more of Eliassen’s amazing aurora pictures on his Facebook page or on 500px, where I originally found his work. Trust me, it’s time well spent.

Image credit: Tommy Eliassen, used by permission.

^* Since it cuts across the two parallel background objects at an angle, it must be a skewting star.

You know why astronomy is cool? Because of things like this:

Galaxy clusters are collections of galaxies held together by their own gravity. We see clusters all over the place, and they’re among the largest structures in the Universe. We can find them at large distances, which means we see them as they (and the Universe) were young — it takes light a long time to travel across the cosmos. Astronomers went looking to find extremely distant clusters of galaxies, and found one at a staggering distance: 12.7 billion light years away!

Here’s an image showing the central part of the cluster:

[Click to bigbangenate.]

Each of those circled red dots is a young galaxy, so distant that the light has been on its way here for more than 90% of the current age of the Universe! And they’re almost lost among all those other stars and galaxies in the image (though their intense red color helps… as to why they’re red, read on).

Finding this cluster was a magnificent achievement. The astronomers used the massive 8.2 meter Subaru telescope to look at large swaths of the sky. They looked at the colors of the galaxies they found (PDF); distant objects would be so far away their light is significantly redshifted by the expansion of the Universe itself (I explain how this works here and here).

Galaxies are distributed throughout space, so you expect to see them scattered across the sky as well as in redshift (distance). When looking at one part of the sky, however, they found an unusually high concentration of galaxies that were very red. Using a different camera on Subaru, they took spectra of those galaxies — breaking the light up into very fine divisions of colors, like a rainbow with hundreds of colors in it — to accurately measure the redshifts of those galaxies. Spectroscopy of objects that faint is no easy task, but Subaru is a big ‘scope, and collect a lot of light even from faint objects at the remote reaches of the Universe,

The astronomers confirmed that many of the galaxies in their sample were at the same redshift (z = 6 for those in the know — which is a mighty big redshift). The odds of these galaxies all being at the same distance happening by chance is extremely small: only about one in a billion! So it’s pretty clear these galaxies really are physically associated with each other.

That is, clustered together.

This makes the cluster the most distant ever found that has been confirmed spectroscopically — one other has been found that might be farther away, but it hasn’t been confirmed yet. At 12.7 billion light years away, that means we see this cluster as it was a mere one billion years after the Universe itself formed! That provides key information about conditions in the early Universe, which are critical to understanding how it formed and changed as it aged.

The cluster itself is vast — it’s something like 50 million light years across. The team of astronomers used various methods to determine its mass, and their best guess is that its total mass is several thousand times the mass of our entire Milky Way galaxy! The estimation methods they used are fairly fuzzy, so it’s not clear how accurate this number really is. Still, the cluster is clearly huge, and massive. If we could see it today, it would probably rank among the largest structures in the Universe.

That’s not terribly surprising, if you think about it: only the biggest monster clusters can be seen at such a mind-crushing distance. The smaller ones will be harder to detect, so we’re likely to find the biggest.

Still, holy cow. I have read and written about extremely distant objects many, many times over the years, and have no doubt: I get chills every single time I think about this stuff. It wasn’t that long ago when the entire human race couldn’t be bothered to look beyond the tip of its collective nose. Now we can look into the fires of the Universe’s birth, into that forge itself, and tease out the secrets of how we came to be.

That’s why astronomy is cool.

Hmmmm… the astronomer in today’s xkcd comic looks familiar, even as a stick figure.

At least he didn’t draw me as a zombie. But I’m no Feynman.

And hey, together with SMBC I think this makes me king of the four-letter comics. I mean, um. Well.

[N.B. And yes, it really is me, I got word from The Man himself. Funny how a minimalist drawing with some context invokes recognition; I've been getting notes from people all morning.]

Well, now I feel bad: when I deflated the Supermoon stuff over the weekend, I swear I didn’t mean it literally!

This amazing shot was taken by astronaut André Kuipers from the International Space Station on May 5, 2012, as the perigee full Moon set behind the Earth’s limb. The Earth’s atmosphere bends light from the Moon, acting like a lens, pushing the bottom part of the Moon up into the top.

Science once again saves me from embarrassment. I was pretty sure the Moon wouldn’t take it personally.

Image credit: ESA/NASA

This is a cool picture:

What you’re seeing is from the NASA/ESA satellite Solar and Heliospheric Observatory, or SOHO. It stares at the Sun all the time, monitoring its activity. This image, from May 3, 2012 is from the LASCO C3, one of the cameras on board. It has a little metal paddle (called an occulter) to block the ferocious light of the Sun; that’s the black bar and circle. The white outline is the position of the Sun and its size in the image.

You can see an emerging coronal mass ejection on the left: that’s the bulb-shaped thingy. It’s actually an incredibly violent expulsion of a billion tons of subatomic particles hurled away at high speed due to the explosive discharge of the Sun’s magnetic field… but that’s not why I posted this picture.

You can also see streamers coming from the Sun; those are places where particles flow freely into space from the Sun. Basically, the magnetic field of the Sun trails into space in those locations, allowing the wind to escape. But that’s not why I’m showing you this picture, either.

Look on the left. See that weird dot with the horizontal line through it? That’s Jupiter! The line is not real; it’s where the camera got overexposed by the planet (digital detectors — like your phone camera — convert photons of light into electrons, and if a source is too bright, the electrons overflow the pixels like water from a bucket. The way the camera works, the electrons flow along the horizontal grid of pixels, creating these lines. This is called "blooming").

Jupiter has been gracing our sky for months, but has been getting further west every night, closing the apparent distance between it and the Sun. It’s on the opposite side of the Sun from us, at a distance of almost 900 million kilometers (550 million miles). When two objects get close in the sky, it’s called a conjunction. When it’s a planet on the far side of the Sun, it’s called superior conjunction. Just so’s you know.

Anyway, I just think this is neat. Jupiter is roughly one-billionth as bright as the Sun, yet there it is in the picture! And even though SOHO is designed to look at the Sun, Jupiter is so bright it’s overexposed. Imagine if the spacecraft moved a bit and the Sun were to peek out from behind the occulter… which can happen. SOHO goes into "safe mode" when that happens, shutting down systems that might get damaged. Every astronomical satellite has contingency plans like that, since it’s hard to send a repair service to most of ‘em. Generally it’s fixable by sending software commands to the spacecraft once the underlying problem has been ascertained.

If you want, SOHO has images online that are updated constantly. Go see what the Sun is doing now! Over the next few days Jupiter will get closer to the Sun, then pass very close to or even behind the disk. LASCO 2, another camera on SOHO that has a smaller field of view but a bit more resolution, should show the moons too when Jupiter moves into its field. I’ll post again when that happens. That’ll be even neater.

Image credit: NASA/ESA/SOHO

So, tonight is the so-called Supermoon, when the Moon happens to be full at the same time it’s at perigee, the point in its orbit closest to the Earth. This makes it somewhat larger and brighter than normal, and that’s getting a lot of attention in the press. I pointed out a few days ago that in reality, you almost certainly won’t notice the difference between this full Moon and any other, mostly because the difference is small, and our eyes and brain are terrible at judging things like that without something to directly compare it to.

I was thinking about this last night as I watched the almost-full Moon rise in the east (which, I’ll add, ironically looked huge due to the Moon Illusion!), and thought of something that might help illustrate this last point.

Monetary eclipse

Imagine you go outside tonight to look at the full Supermoon rising in the east. Imagine also you’re holding a US dime in your hand (if you live in another country, feel free to substitute your local currency, but beware of the math; hang on a minute to see).

Let me ask you this: How far away would you have to hold the dime so that it appears as big as the Moon to you?

A few inches? A foot? (Convert to metric if you wish). Go ahead, guess!

… OK, ready? [Answer is below the fold so as not to spoil it.]

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