Tag: Saturn

Saturn, raw

By Phil Plait | June 17, 2012 9:12 am

There are times when I see an astronomical image so powerful that I’m momentarily stunned, my brain kicked hard enough that all I can do is stare at it and soak it in.

This picture of Saturn is the latest to affect me this way:

[Click to embiggen.]

This astonishing image was taken on June 13, 2012 by the Cassini spacecraft when it was 2.6 million kilometers (1.6 million miles) from the ringed planet — that’s more than six times farther than the Moon is from the Earth. Even then Saturn’s rings span too broad a space to see completely. But artistically, perhaps, it works even better; their vast size is intimated instead of spoken aloud, the thousands of thinner component rings only hinted at. You can see their shadow on the tops of Saturn’s southern clouds thousands of kilometers below, the Sun shining down from the north — to the left as seen in this oddly-angled shot. The clouds themselves are almost featureless, but you can still see some boundaries between oppositely-blowing wind belts, and even the long, snaking remnants of a titanic storm that raged in the north last year. It’s incredible.

Moreover, this image has not been processed in any way: it’s raw, taken right off Cassini’s detectors and sent home to Earth (I shrank it a bit to fit the blog, but otherwise didn’t touch it). The sky behind the planet isn’t entirely dark, there are a handful of hot pixels you can see on the planet, and there are other defects here and there that catch the eye. But even that takes nothing away from the power of this image to me, and in many senses actually adds to it.

Cassini is out there. It’s well over a billion kilometers away from Earth and the Sun’s warmth, moving through space, enthralled by the deep and long-reaching gravity of this huge planet. Quietly, obediently, and with hardly any glitches or complaints, it takes picture after picture, reads and records the environment around it, saves the data, and then sends it via radio waves back to Earth, no more than a blue dot in its sprawling sky.

This is what I see, this is how my mind reacts once my brain has a moment to compose itself. It’s a fantastic tableau, a static shot of a magnificent planet such a long, long way away. And always, when I see these, I also think: we did this. We flung this complex machine into the distant solar system to study Saturn, and we did it because we want to find things out.

It is among the best things we do.

Image credit: NASA/JPL/Space Science Institute. Thanks to Michael Interbartolo for posting about this latest batch of raw images in his Google+ stream.

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MORE ABOUT: Cassini, Saturn

The ups and downs of Saturn pictures

By Phil Plait | June 11, 2012 1:00 pm

When I look at Cassini images of Saturn — with its multitude of rings and fleet of moons — I am inspired, moved, and even awed.

And sometimes I laugh. When I saw this image, for example, I actually chuckled to myself. Why?

[Click to encronosenate.]

This gorgeous shot was taken on December 30, 2011 and released just today as the Cassini Image of the Week. It shows Saturn’s gorgeous rings seen nearly edge on, and the tiny moon Epimetheus, only 113 kilometers in diameter, next to them.

It’s a lovely image to be sure, and my very first thought was; I wonder if Epimetheus is closer to us than the rings, or farther away? If we’re looking down on the rings, from the north, then Epimetheus is closer to us. But if we’re looking up from underneath the rings, Epimetheus is on the other side of the rings. I could mentally switch my perspective back and forth, but I couldn’t tell which view is correct! This prompted my chuckle, as I wryly smiled at my brain’s confusion (I love optical illusions).

So take another look: are we looking down on the rings, or up? Hint: the Sun is shining from the north, down on the rings.

It’s a bit of a conundrum, isn’t it? Just by looking it’s almost impossible to figure out! If you’re familiar with Cassini pictures, the rings look subtly different if they are illuminated from above and you’re looking at them from underneath, and vice-versa. But it’s hard to tell. And to be honest, I wouldn’t have known without reading the caption for the image.

The answer is we’re looking up. The Sun is shining down on the top of the rings, and we’re looking up from underneath, putting wee Epimetheus about 1.5 million kilometers (900,000 miles) from Cassini when this picture was taken. If it helps, hold up something round like a DVD and look at it from underneath. As another helpful guide: in the image above, the part of the rings at the top of the picture are closest to you, the bottom farther away, and Epimetheus father still.

And I bet that even knowing that, some of you are having a hard time picturing it. Our brains are funny things, easily fooled when there’s symmetry in a picture, especially when that picture shows an unfamiliar object. I’m sure Carolyn Porco can just glance at something like this and figure out everything she needs to understand the geometry! I’m not so sure I could’ve.

Remember: seeing isn’t always believing. It’s easy to fool our eyes and brain, but in the end the Universe knows what it’s doing.

Image credit: NASA/JPL-Caltech/Space Science Institute

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Saturn, surreally

By Phil Plait | May 23, 2012 7:00 am

Take 7+ years of Saturn observations by the Cassini spacecraft, stitch a whole lot of them together into short, film-noir-like segments, and add a Beethoven soundtrack. What do you get? Awesomeness.

The video was put together by Nahum Chazarra, who says on Twitter he’s a "Geology student, science lover". There’s literally too much in this to describe! Moons, rings, the planet itself… but I think my favorite part is when some object, usually a tiny moon, stays centered while the rings and planet and other objects wheel around it. It’s a change-of-perspective effect, but amazing to watch. And you really can’t go wrong with "Moonlight Sonata".

Something like this video has been done before (specifically here and here, and both are well, well worth your time to watch) but to be honest it’s impossible to get too much of this. The changing lighting and exposure, the sometimes jerky apparent motion (due to the inconstant times between exposures combined with the spacecraft’s motion), and the simply jaw-dropping spectacle of the ridiculously gaudy Saturnian system, all combine to make this an engaging and even mesmerizing show.

Tip o’ the dew shield to Dark Sapiens.

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CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures
MORE ABOUT: Cassini, Saturn

Ice moon, ghost moon

By Phil Plait | May 10, 2012 8:55 am

One of my favorite things to do is take a gorgeous astronomical image and pierce down into it, finding some detail not discussed in press releases and other articles.

On the other hand, sometimes I’ll post a picture because it’s so, so cool:

[Click to encronosenate.]

That’s a shot of Saturn’s rings and moons by the Cassini spacecraft, taken in mid-April 2012. Cassini was nearly in the same plane as the rings, so they look like a knife cutting across the image. The bright moon is Enceladus, tiny and icy, almost but not quite full as seen from this angle.

But the scene stealer is Titan, the moon as big as a planet — bigger than Mercury, actually — looming in the background, nearly invisible. This image, taken using a filter that only lets through green light, shows just how much darker Titan is than Enceladus. The bigger moon is shrouded in a thick, hazy atmosphere, and reflects about 1/5th of the sunlight that falls on it. Enceladus, on the other hand, is covered in ice, and reflects nearly all the light that falls on it. So the brightness ratio you see here is real: Titan really is far darker then Enceladus.

… and there you go. I drilled down a bit into the picture’s science anyway. I guess I had to. It’s in my nature; when it comes to science, I’m reflective too.

Image credit: NASA/JPL-Caltech/Space Science Institute

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Saturn broods while a storm dissipates

By Phil Plait | April 30, 2012 5:48 pm

I’m in the middle of writing up a ton of stuff for the next couple of days, so let me just leave this here: a lovely image of Saturn and its moon Tethys and Enceladus, courtesy of Cassini:

[Click to encronosenate.]

Sigh. So pretty. Tethys is the moon to the left, just above the rings, and Enceladus is right next Saturn, just below the rings. Cassini was just 1° south of the ring plane when it snapped this shot, so they appear very thin. It’s approaching northern hemisphere summer for Saturn, though, so the Sun is shining down on the rings, and they cast a wide shadow on the planet’s southern hemisphere cloud tops.

I can’t help noticing the long, thin, white ribbon of clouds about 2/3 of the way up Saturn’s northern hemisphere. That looks very much like the remnants of the gigantic storm from late 2010 that was so long it actually wrapped all the way around the planet! If you think it’s crazy to think a storm could last that long, take note that Jupiter’s Great Red Spot is at least 350 years old — it was discovered around 1665, and who knows how long it was around before then? And heck, Saturn itself suffered through a huge lightning storm for eight months.

Our gas giants don’t screw around. When they do something, they do it big.

Image credit: NASA/JPL-Caltech/Space Science Institute

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Mesmerizing time lapse of Saturn and Jupiter from spacecraft

By Phil Plait | April 30, 2012 6:29 am

One of the single greatest advantages of the modern age of astronomy, in my opinion, is that digital images from telescopes and spacecraft — and telescopes on spacecraft — have been placed in the hands of everyone. It can take years of training to correctly process and interpret astronomical data, but even without that these images can be put together to make art, scenes of surpassing beauty that professional astronomers might not even think to create.

Dutch video editor Sander van den Berg looked at Cassini and Voyager images, and saw beyond the raw data into the beauty of motion in them. He created a video that is stunning. Stunning. He calls it, simply, "Outer Space".

The events depicted take days, even weeks to play out. Yet somehow, the quick shots and fast cuts — necessary because in many cases there really aren’t very many images to play with — add to the majesty and grandeur of what you see. I suppose that’s no more paradoxical than having canvases far bigger than Earth, yet loaded with detail packed into those vast frameworks.

The Universe is magnificent on every scale, both in space and time. That’s one of the reasons I like working there.

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The look of a Titanic moon

By Phil Plait | April 12, 2012 9:30 am

Astronomical imaging is an interesting process. The most common question I get when I show a picture is, "Is this what it would look like if you were actually there?"

That’s a tough question to answer in many cases, because our eyes see in a different way than cameras take pictures. We have receptors in our eyes that are sensitive to red, green, or blue light, and they send signals to the brain which then constructs a "true color" image from that. In astronomy, we use filters to mimic that, but they don’t actually perfectly represent the way our eyes see. And even after you get the picture, there are adjustments in contrast, brightness, and so on that can alter a photo.

A few months ago, the folks at Cassini released a really cool picture of Saturn’s moon Titan. It’s a great shot, have no doubt, but amateur astrophotographer Gordon Ugarkovic — who has some experience putting together color pictures from Cassini images — felt that processing the image in a different way might represent natural color better. So he reprocessed it, producing this amazing image:

[Click to encronosenate.]

All by itself, that’s a stunning shot. Titan is larger than Mercury, but still dwarfed by the gigantic planet it orbits. Titan has a thick atmosphere, and you can see some details in it, like the "polar hood" over its north pole. Also, a really neat effect is on Saturn itself. You can see the rings, as well as the shadow of the rings on Saturn’s cloud tops (below the rings themselves). Near the edge of Saturn, the shadow dips downward, hooking down a bit. That’s a product of several effects, including refraction; the bending of light as it passes through the atmosphere (similar to why a spoon looks bent in a glass of water).

It’s interesting to compare Gordon’s version to the one released by Cassini as well (shown here; click to embiggen). Both are beautiful, interesting, and show a lot of detail. The "official" release is darker, a bit, which is the most obvious aspect. Gordon’s shows details in Titan’s polar hood better, but I see more subtle variations in Titan’s atmosphere overall in the official shot, and perhaps better detail in the ring shadows, too.

So which one is better? Neither! They both are amazing, and show slightly different things. One might appeal to you more in an aesthetic sense, or in a scientific sense, or because you’d rather see details in Titan versus Saturn, or whatever. But in my opinion, it’s OK to like both or neither or one over the other for whatever reason you prefer.

In astronomical imaging — something I did professionally for over a decade — the image is never really what you’d see if you were there, because the instant you use a camera and a telescope you’re already two steps removed from real vision. You can try to get as close to what the human eye would see as you can, but I think in most cases that’s a conceit, something that’s interesting to our minds but perhaps not our eye.

And like all photography, this is art. If you want to display an astronomical object and are being true to what you are showing, then it’s OK. These images done for press releases or simply for their own sake are meant to inspire our imagination, fire up our curiosity, and see their beauty.

Beauty that is, at the very least, in the mind’s eye of the beholder.

CATEGORIZED UNDER: Astronomy, Pretty pictures

A warm greeting for the frigid Moon

By Phil Plait | March 9, 2012 10:47 am

Dave Brosha is a photographer who loves to capture spectacular and unusual night sky scenes — his picture of another photographer silhouetted against an aurora graced this blog in November 2011.

He just sent me two more he took last night. He went to Yellowknife, in the Northwest Territories of Canada. The aurorae were active last night as the Sun’s recent hissy fit sparked a geomagnetic storm, but by the time Dave go his equipment set up, the Moon was up and the aurorae fading. But never one to waste an opportunity, he took this incredibly dramatic and moving picture:

Stunning. [Click to enannulenate.] Ice crystals suspended in the air refract (bend) light from the Moon, and due to their geometry they create a ring around it. This is common in winter, but it’s rare — at least in the lower 48 — to get one this bright. The bright "star" on the edge of the ring at the top is actually Mars, which is terribly bright and ruddy in the night skies right now. The fainter star inside the halo is Denebola, the tail of Leo.

He also took this more upbeat picture (click to embiggen) which is another fantastic shot of the halo. You can still see Mars, with the bright Regulus (the heart of Leo) to the right, and just to the left of his hand is either Saturn or the bright blue star Spica in Virgo; I’m not sure which since they’re close to each other in the sky right now. Given how far it’s outside the halo, I’m leaning toward it being Saturn with his hand blocking the view of Spica. As an added bonus, you can see a faint arc of light at the top of the halo, called an upper tangent arc; these are more rare. I’ve only seen them a handful of times near the Sun, and never from a Moon halo!

Having spent a lot of time — a lot — out in the cold waiting for that one great shot, that one great view through the telescope, I can sympathize with what Dave went through to get these… and know he agrees that it was absolutely worth it.

Image credits: Dave Brosha, used with permission.

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Worlds bigger than worlds

By Phil Plait | March 1, 2012 7:00 am

Because I love each and every one of you, here is a fantastic portrait of two worlds: Saturn and its ginormous moon Titan, courtesy of the Cassini spacecraft:

Isn’t that breathtaking? [Click to encronosenate.]

I love the panoply of shadows from the rings on the cloud tops of the gas giant planet, clearly showing Saturn has not one big ring, but thousands of thin ringlets. You can also see subtle patterns in the clouds as well. If you look very closely, you’ll see the shadow of the moon Prometheus on the left just below the ring shadows — the moon itself is the white speck just above the rings to the right, just to the right of Saturn’s limb — as well as the shadow of the moon Pandora on the right below the rings. Pandora itself is well outside the frame of this shot though.

Of course, fuzzy Titan looms of the planet’s edge on the right as well. Titan is huge, bigger than Mercury, and if Saturn weren’t there might be considered a planet in its own right. But definitions aside, Titan is a varied and complex place, worthy of intense study. It has weather, lakes of liquid methane, dunes blown and sculpted by wind, and boulders made of water ice harder then rock is on Earth.

Who wouldn’t want to take a closer look at a world like that?

Image credit: NASA/JPL-Caltech/Space Science Institute

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The staring eye of a crescent moon

By Phil Plait | February 10, 2012 10:39 am

Sometimes, the images from the Cassini Saturn probe are so cool it’s tempting just to post them and say, "Look at THAT!"

See what I mean? [Click to gigantesenate.]

But of course, I can’t just leave it at that. This image, taken on January 4, 2012, is a bit different than most. Sure, we see Saturn’s magnificent rings, nearly edge on from this perspective. And we’ve seen this icy moon Enceladus many, many times (see Related Posts below for tons more pictures). Look at the bottom of the moon: see those fuzzy streaks? Those are geysers of water spewing from cracks in the moon’s south pole! Cassini has been studying them intently ever since they were discovered; they are proof that liquid water exists under the surface of Enceladus, though it’s still being argued over whether it’s in pockets, like lakes, or the whole moon has an ocean of water under the surface.

Despite all that, I keep getting drawn to the crescent shape itself. We can never see that from Earth. Saturn is much farther out from the Sun than we are, and geometry demands that from home we always see these worlds nearly fully lit by the Sun. The only way to see them like this is to go there.

But also, that giant circular feature is really interesting. It’s big, maybe 200 km (over 100 miles) across, and a bit darker than the surrounding surface. I tried locating it on an atlas of Enceladus, but it wasn’t obvious at all. I thought it might be an impact basin, but a little scrounging online led me to a paper by Cassini imaging team leader Carolyn Porco, which says there are no large impact basins on Enceladus! So what is it?

Well, why not go to Dr. Porco herself? I sent her a note, and she kindly replied. That region is called Diyar Planitia, and it stands out among the surrounding terrain because it’s much smoother. It does have narrow surface features, but they’re too small to be seen at this resolution. At the low angle at which we’re seeing it here, it looks a little bit darker than the rougher terrain around it, so it’s easier to see (which is why on an atlas it’s harder to find). It is roughly circular, but that may simply be coincidence. Enceladus has been massively resurfaced, with some areas much older than others, due to various forces under the surface — looking this all up I learned a new one, called diapirism, where lower density material underneath higher density material can rise up and break through. That’s one process that’s helped change the surface of Enceladus over the eons.

That’s pretty nifty. And think about that! Today I learned of what is to me a new region of the solar system, one that has an interesting and complicated history, molded by vast forces over long-stretched times, one of which was also new to me. How wonderful to get all that from what’s otherwise just a pretty picture!

But of course, in science, there’s no such thing as just a pretty picture. Science is a tapestry, a vast complex fabric interwoven with countless threads. Each of those threads is amazing, each important, and each leads to another. And that’s where the true beauty of science lies.

Related posts:

Enceladus sprays anew!
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Icy moon and distant rings


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