Bad Astronomy Blog
I’m thankful for a lot of things in life — though appreciative might be a better word — but if I had to assess a list of astronomical gifts, then Saturn would be very high on that list.
This ridiculously gaudy bauble of the solar system never ceases to amaze me, filling my sciencey brain with wonder as it overwhelms my artsy brain with beauty.
So just to get you kickstarted for Thanksgiving, here are three portraits of Saturn for which we can all be grateful.
Up first: Rings and shadows.
This image, taken by the Cassini spacecraft in Aug. 14, 2014, shows nearly the entire face of the planet. That’s no small feat, given Saturn’s 116,000 km girth.
Cassini was almost directly above Saturn’s equator when it took this, so the rings, similarly latituded, are seen as a narrow ribbon around the planet. But that’s an illusion of perspective; the rings are 270,000 km across, a huge span. That’s revealed by their shadow on Saturn’s southern hemisphere; a series of concentric arcs darkening the cloud tops.
I like how different rings cast darker or lighter shadows. The inner C ring is sparse, but the main B ring is thick and broad. The A ring, outside of B, is slightly less dense, so the shadow is lighter. The gap between them is called the Cassini Division, and since there’s less stuff there, it appears as a bright band on Saturn (it doesn’t cast a shadow, really). You can also see the Encke division, the very narrow strip near the bottom of A’s shadow. The shadows are like the rings in reverse, both in brightness and order.
By the way, did you spot the moons Tethys (off to the right) and Mimas (just above the rings, to the lower right of center)?
Next up: Light and shadowplay.
Cooool. The images making up the video, taken by Hubble, are from 1995, when Saturn’s tilt brought the Sun shining almost directly along the plane of the rings. That’s how the moons (Enceladus, Mimas, Dione, and Tethys) can cast long shadows on them. The video shows about 9.5 hours in the life of moons, and you can see just how far they move in that short time, tugged by Saturn’s immense gravity.
This spectacular shot threw me for a moment. I had never see the clouds on Saturn mixing like that before; usually they stay separate. But this is an image taken using a filter that only allows red light through, where methane absorbs light. That means you’re seeing the very top of the clouds, where mixing of winds is more common. That vortex appears to be drawing material from the bright band next to it. It’s a good reminder that air is a fluid — literally, something that can flow.
Perhaps it’s a bit odd of me to be thinking of Saturn on a day like today, but you know what? I’ll take odd, if it means being able to appreciate the intense and wondrous beauty of the natural world… or worlds.
In May 2013, the Aleutian island volcano Pavlof erupted mightily, blowing a stream of ash into the atmosphere and messing up airplane travel.
Last week, it was at it again. This eruption was even more violent than last year’s; the plume went nine kilometers into the air, and was hundreds of kilometers long. It was seen by the Landsat 8 satellite on Nov. 15:
There’s a weird beauty to such things, as awful as they can be. I see them, I suppose, like a rabbit sees a snake: morbid fascination (mixed with a small to fair dose of terror). Even though, in terms of human settlements, Pavlof is remote, it still can muck up airplane travel. Ash is made of fine but very jagged particles of pulverized rock and glass, and if it gets into an airplane engine it can jam it up but good.
That’s why, as I pointed out in last year’s article, we need the Alaska Volcano Observatory… which is generally under threat of a budget ax. That’s nuts, but then, that’s politics these days. When you have a group that denies the existence of everything around them, then dipping your toe into the Presidential election campaign by mocking volcano observatories probably seems downright sane in comparison.
Take one part Himalayan mountain, one part gigantic galaxy (seen from a distance), and one part photographer (pre-mixed with talent + adventurousness), and mix them together to produce three minutes of magnificence:
That amazing video was shot by Alex Rivest (who previously has been featured on the blog for two stunning time-lapse videos using astronaut photography from the International Space Station). Just the view of the last rays of the setting Sun washing the peak of Mt. Everest in yellow light is worth the watch, but then the Milky Way, our home galaxy, looming over it, dwarfing our sense of scale and distance? Gorgeous.
Rogelio Bernal Andreo is an astrophotographer… but saying that is like calling a world-class chef a “cook”. Andreo is a master, one of those people who can tease photons out of the sky and then turn them into works of art that nearly defy description.
For example, here is his mosaic of the sky showing two stunning objects: The California Nebula, and the magnificent Pleiades star cluster:
Holy. Haleakala. Yes, you really really want to download the fully embiggened version of that, because it’ll freeze your brain with its beauty and scope.
It’s hard to know where to even start with this! So let’s take it one at a time. On the left is the ruddy glow of the California Nebula, officially called NGC 1499. It’s a vast cloud of gas and dust stretching several dozen light years in length, which is huge on anyone’s scale. It’s part of a large cloud of gas that long ago condensed to form baby stars. But don’t be fooled by the adjective; these are very, very ill-tempered babies indeed. Take a closer look:
See that bright star just to the right of the gas, inside that arc of gas? That is Xi Persei, also called Menkib. It’s a beast, a monster 30 times the mass of the Sun, and blasting out light at a hair-raising 250,000 times the rate the Sun does. That’s so much radiation that we think that’s what’s setting the nebula aglow. Remember, that gas cloud is over 400 trillion kilometers long, and it’s being lit up by a single star. The star and cloud are something like 1000 light years from Earth, yet the star is visible to the unaided eye. From that distance, you’d need a decent telescope to see the Sun at all.
The nebula is named because of how much it looks like its eponymous state, and I have to agree, it’s a good match (too bad it’s not nearer the North America Nebula). The ribbons and filaments you see inside the cloud are due to shock waves inside the gas, where waves of material slam into slower stuff, compressing it. The gas is expanding because long ago, several of the massive stars born from it lived out their lives and exploded as supernova, dumping huge amounts of energy in to the gas and causing it to rush away. The California nebula is only one segment, one arc of a far larger shell of gas that we cannot see because it has no nearby powerhouse stars illuminating it.
On the right of Bernal’s magnificent mosaic is the famed Pleiades cluster — the Seven Sisters — a collection of youngish stars all formed from a single cloud of gas and dust. The cluster is very roughly 400 light years away (much closer to us than the California Nebula), big enough and bright enough to be seen with the naked eye. In fact, a lot of people mistake them for the Little Dipper!
Deep, high-resolution pictures of the stars show them lighting up diaphanous sheets of material around them. Years ago, it was thought this was the material from which the stars formed, and that always bugged me. The cluster is about 100 million years old, which is way too old to still be surrounded by its birth cocoon. And, it turns out, that intuition is correct: that material belongs to an entirely different cloud of dust, and it just so happens the cluster is passing through it right now! Bernal’s photo makes this more clear; there are vast swaths of dust littering that whole part of the sky.
I have to point out the difference in color between the Pleiades and the California Nebula. In the latter case, the gas in the nebula is being excited by ultraviolet light from Xi Persei. These photons hit the hydrogen atoms in the gas and are absorbed by the electrons in the atoms. The electrons dump that extra energy by emitting light, predominantly in the red part of the spectrum.
In the case of the Pleiades, the light is coming from dust near the stars that’s reflecting the starlight. The stars are blue, so the reflected light is blue, too. Because of this, we call the California Nebula an emission nebula, while the Pleiades dust is a reflection nebula. The physics of this is actually pretty neat, and if you want to read more I have a detailed (and hopefully clear) description in an article about a gorgeous nebula that is both reflecting and emitting light. You really want to see (and read) that.
And do you want to know another amazing thing about this picture? Take a look at the Pleiades again in the big version of the full mosaic. See the diamond of four bright stars, just above the fifth star? On the sky, the full Moon is just about the same size as that diamond (this is shown in the zoomed picture above for clarity).
Now take a step back, and look at this full mosaic again. The whole thing is a staggering 18° across, 35 times the width of the full Moon! How much of the sky is that? Stand up, and hold your arm out in front you. Bend your wrist in, so you’re looking at the palm of your hand and your fingers: If you held your hand like that up to the sky, it would be cover about the same amount of real estate as Bernal’s photo. Wow.
And one final note: Years ago, I picked his “Orion from Head to Toe” as the best astrophoto for 2010. I cannot stress enough how much you want to click that link. To put this in perspective, I have seen thousands of astrophotographs over my life, and that Orion picture is one of my favorites of all time.
As usual, I have to smile wryly when I hear people try to distinguish art from science. The Universe is both, folks. You may try to tear them apart, but you cannot, for the artistry of the Universe is forever intertwined with how it works. They drive each other; the science is why the art is beautiful, and the art is one of the reasons we pursue the science.
Today (Nov. 23, 2014) at 21:01 UTC (16:01 Eastern), a Soyuz rocket is scheduled to launch from Baikonur, Kazakhstan. On board will be three human beings: American Terry Virts, Russian Anton Shkaplerov, and Italian Samantha Cristoforetti.
There are some cool things about this particular crew. For one, as AmericaSpace points out, all three are in the Air Force, though from three different countries. I’ll add that in our collective pasts, all three countries have been enemies at one point or another. Yet here we are, all three not just cooperating but sending members of their military into space together to work as a team.
That makes my heart soar.
All three are on Twitter: Virts, Shkaplerov, and Cristoforetti. Together, they make up the rest of the crew of Expedition 42, which began when the ISS hatch closed on the Soyuz capsule that brought three members of Expedition 41 back to Earth — at the time, three astronauts stayed on ISS, and now the team will be at full speed with six members.
This isn’t your ordinary space station crew. After all, would your everyday astronaut team pick this as their promotional poster?
Heart? Still soaring.
I want to single out Cristoforetti for a moment. Not because she’s a female astronaut, though it’s perhaps worth noting that two women (the second being Elena Serova) will be on ISS together for only the second time since the orbiting facility was launched. And not because she’s the first astronaut named Samantha, either.
No, it’s because she’s cool. How do I know?
Back in August she tweeted a photo of the cabin of a Soyuz capsule. The seats are far enough back from the controls that they need to use extension wands to press some of the buttons, and Cristoforetti noted that the paper work is done to get her pointer to fly.
I couldn’t help myself. I replied to her, and this conversation ensued.
[Note my typo; I meant “ad astra”, which means “to the stars”, and is part of the phrase per aspera ad astra, or “through hardship to the stars”.]
All very nice and fun, and I got a good chuckle out of it. But then she became my favorite astronaut in the whole world Universe when she picked the conversation back up a little while later:
And before you ask: I asked her, and she’s not bringing it into space with her. There goes the best promotional picture ever taken! Oh well.
Still: my heart is now well above the Kármán line.
So then, let me finally add: Per cordibus nostris, ad astra.
Well, this is interesting: The folks at the Jet Propulsion Laboratory and SETI Institute have just released a remastered image of Jupiter’s moon Europa, and it’s breathtaking:
That’s not even full-res; click it to see it in its splendor.
Europa is 3120 km (1930 miles) in diameter, a hair smaller than our own Moon. Unlike our Moon, which is rock through and through, Europa has a rocky core covered with water. And by water, I mean liquid water, an undersurface ocean covered with a kilometers-thick shell of ice. The water may be in a layer 100 km thick, and salty, making it a true ocean. In fact, it may have more liquid water than Earth does!
The cracks you see are where ice floes fit together; the brighter areas are nearly pure water ice, but the red/orange regions are cracks, possibly where briny water has been squeezed to the surface, and materials in it chemically affected by the intense radiation environment surrounding Jupiter (caused by its very strong magnetic field interacting with material blasted out by volcanoes on Jupiter’s moon Io).
All of this has made Europa a prime target for exploration for a long time. I was going to write a bit about that, but then saw that JPL made a very informative video explaining it all.
That video is very well-done, and as I watched it I couldn’t help but think it felt like a trailer or promotional video for a new mission in the works. I know a lot of planetary astronomers have wanted to send a dedicated mission to the moon to investigate it far more thoroughly…
… and then I found that, due to the mid-term elections, Rep. John Culberson (R-Tex) is now head of the House's Commerce, Justice, and Science (CJS) appropriations subcommittee. He’s long been an advocate for a Europa mission.
It cannot be coincidence that this new image and video were put out now. The feeling I got while watching it, I suspect, is based on reality. I will not be surprised in the least if, for the next fiscal year budget, NASA asks for a Europa mission, including something as dramatic and unprecedented and as some hardware that can penetrate the ice and take a peek into Europa’s dark, briny depths.
I can’t say I’m opposed to that. There’s a lot of reasons to look around Europa as the video makes clear. You could argue the same for Enceladus, the icy moon of Saturn that has water geysers erupting from its south pole. In many ways Enceladus is a juicier target… but on average Saturn is twice as far from Earth as Jupiter, making the mission longer and more difficult. I figure go close first, learn the lessons, then push the distance boundaries more. As much as I’d like to see what’s under the ice of Enceladus, the shorter trip to Europa makes it an easier goal.
I’ve had my issues with Culberson about NASA, but, depending on how it’s done — extra funding for NASA so that no current or other future missions will get bled of funding, for starters — then an orbiter, lander, and sub-lander to Europa could very well be something I could get behind.
This is something I think NASA should be doing: Pushing the frontier, doing what only a national space agency can do. This would be a huge undertaking, and one that would fire up the public imagination like nothing before it since Apollo. I'd very much like to see that happen.
Last week, I highlighted an amazing video of the Sun taken from space in super-hi-def resolution, put together from NASA imagery by James Tyrwhitt-Drake.
Today, how about we turn that around, look down, and do the same thing for our fair planet?
Here’s the Earth, as seen by the Russian Roscosmos’s Elektro-L satellite from May 15 – 19, 2011, and put together into a video again by Tyrwhitt-Drake. Set it to maximum resolution and make it full screen, and soak up the incredible beauty of home.
Fantastic, isn’t it? But it also takes some explaining.
First, Elektro-L is an Earth-observing weather satellite. It’s in a geosynchronous orbit, meaning it goes around the Earth once every 24 hours, the time it takes the Earth to spin once. From our point of view that means the satellite is fixed in the sky, neither rising nor setting. From the satellite’s point of view the Earth always shows the same face; looking down it always sees the same part of Earth. That’s why a geosynch orbit is so useful for weather. The video makes that obvious, too.
The satellite has cameras sensitive to visible light — the kind we see — and near-infrared. Plants reflect that kind of light very strongly, so places where there’s vegetation show up strongly in the satellite images. Normally those are colored red in pictures, but for this video Tyrwhitt-Drake colored that channel a more natural-looking green. Plants aren't the only thing that reflect IR light, so some places look green that aren't; note Saudi Arabia, for example, and the Sahara, which have a yellow-green tint from sand.
If the motion looks odd to you, that’s because Tyrwhitt-Drake had to interpolate between frames taken every 30 minutes by Elektro-L (I explain how this is done in a post about a video of the Curiosity Mars rover landing). It creates an odd flowing effect, but is far better than the jerky snap between images taken so long apart.
Also, the video only shows the northern hemisphere first, then the southern flipped over (note the shadow line between night and day, called the terminator, moves the other way), and then finally the whole Earth at lower but still spectacular resolution.
Incredibly, the images off the satellite are originally 11k x 11k (each 120 megapixels!), which Tyrwhitt-Drake resized down to 50 percent, presumably so it would take less than a century to render the video. He says his 5568 x 5568 pixel video is available upon request. That would be amazing… if I had a monitor with enough resolution to see it! Maybe I could stitch 25 TVs together…
Tip o' the chlorophyll to Fraser Cain.
Ten years ago today — on Nov. 20, 2004, at 17:16 UTC — A Delta II rocket thundered into the sky. Sitting inside the payload cowling was NASA’s Swift observatory, awaiting its chance to revolutionize astronomy.
Swift was sent into orbit to look for gamma-ray bursts, the most violent bangs in the Universe since The Big One. These explosions are the birth cries of black holes, and occur somewhere in the Universe every day.
They’re so luminous they can be seen clear across the Universe, but so short in duration that in some cases, literally, if you blink you’ll miss them. They made them incredibly hard to study; it was a lucky break when a burst in 1997 was caught by an X-ray satellite called BeppoSax, the first to have its distance accurately determined; it was a whopping six billion light years away! The history of GRBs involves the cold war, nuclear bomb testing, and many, many years of astronomers scratching their heads. It was one of the most enduring mysteries in astronomy*, and Swift helped us understand them better than any observatory before it.
Swift was designed and built to detect GRBs in gamma rays, X-rays, ultraviolet and optical light — a huge chunk of the electromagnetic spectrum — and rapidly slew over to point at them, sometimes in well under a minute. It was named after the acrobatic bird, which catches huge numbers of insects on the fly.
It turned out to be a good name.
Swift quickly became the go-to observatory for GRB detection. By the end of 2004 it found nine GRBs — averaging about one per week — even before its observational methods had been fine-tuned. As I write this, after ten years, it’s detected 921 of these cosmic explosions! That’s stunning.
As soon as it detects a burst, it sends the coordinates out via the Gamma-ray Coordinates Network. Telescopes hooked up to the network can automatically look for the burst within moments of its discovery that way, and hope to catch the rapidly fading afterglow, caused by the initial explosion sending out so much energy and high speed matter that in a few seconds it dwarfs the Sun’s entire energy output over its entire 11 billion lifetime!
GRBs are awe-inspiring.
Along the way Swift’s also seen a magnetar explosion (one of the very few astronomical events that actually freak me out due to their mind-crushing violence and scale), watched a neutron star get torn apart by a black hole (!!!), observed hundreds of galaxies, exploding stars, asteroids, comets, and more... including, get this, the single most luminous event ever witnessed by humans up to that time. And Swift is still up there, orbiting the Earth, scanning the skies diligently and patiently, waiting for the next burst. You can even see a map of the sky showing where the latest bursts have been seen.
Although I wasn’t involved with the science of the mission except tangentially, I worked for many years on the education and public outreach part of the mission. I wrote countless articles about Swift, including much of the EPO website. Our team at Sonoma State University designed a lot of activities for kids using Swift science, including brochures, a paper model of the satellite, classroom activities, a planetarium show, and a lot more. I’m still pretty proud of the work we did for Swift.
And I’m proud of the satellite. It was relatively inexpensive (the total mission cost was about $250 million) and it’s performed nearly flawlessly in the ravages of space for a decade. It’s a paragon of international cooperation to study the Universe, and a true achievement for NASA.
Congratulations to the entire Swift team, and happy anniversary. You deserve it.
On Nov. 14, 2014, something exploded over the skies of the Sverdlovsk region of Russia, about 1500 kilometers east of Moscow. I’m not sure what it was, but the videos coming out are pretty dramatic:
As we learned from Chelyabinsk in 2013, Russian cars commonly have dashboard cameras, so I’m hoping more footage will surface soon. A couple of teenagers managed to catch it on a phone camera:
It’s very cloudy, but the light can be seen through them. The first obvious guess is that this was a bolide, a fireball caused by a chunk of debris entering our atmosphere from space at high speed. These happen pretty often.
The color is odd; the reddish glow, if accurately portrayed in these videos, isn’t something I generally see in bolide videos and photos (or from the few I have seen with my own eye). They tend to be green or blue, or just white. Not always, but just in general. of course, the clouds may be affecting the color, too.
Also, it’s really hard to tell, but it doesn’t look like the light is moving, as you might expect from a meteor. The videos are both shaky, so it’s not easy to measure that. The movement looks minimal to me, though. That could be geometry: If the meteor is moving across your line of sight then there is a lot of motion, but if it’s headed more or less toward or away from you as it moves through the air, sideways motion will be low. I’d expect that the two videos would show different geometries, but again they’re so shaky it’s hard to tell.
There are some preliminary flashes in the teenagers’ video a few seconds before the big one, and that’s consistent with a meteoroid breaking up as it comes in. As a big rock rams through the air at many times the speed of sound, the pressure breaks the rock up into smaller pieces, creating flashes as the energy of motion is converted into light and heat. There can then be a much larger flash as the smaller rocks all disintegrate rapidly.
If this wasn’t a bolide, what was it? Beats me. It’s a bit odd to think that a biggish rock from interplanetary space is the most mundane and prosaic explanation, but in this case it is! However, I won’t make up my mind until more evidence is in.
Tip o’ the Whipple Shield to NASANeoCAM on Twitter.
— with apologies to Robert Browning
We humans have lived on Earth a long time. Hundreds of thousands of years, give or take, depending on what you define as human. And all that time we have yearned to reach the stars, to explore, to find out what exists elsewhere.
We’re just now starting to do just that. We’ve only been able to fly for a little over a century, and the elapsed time since we first left our atmosphere can be counted in decades, less than a human lifetime. We’re taking our first tentative steps.
And yet we have accomplished so much! We’ve sent our spacecraft to every major body in the solar system, and quite a few minor ones besides. We’ve continuously occupied space for years, and we’ve launched observatories into orbit that examine the Universe in every wavelength regime of the electromagnetic spectrum.
And we’ve done even more: We’ve set down on other worlds. Certainly, most have been through our robotic proxies, but given the inhospitable nature of so many of these worlds, that’s not surprising.
And now we can include an entirely new body to that list: a comet, thanks to the Philae lander sitting on the surface of 67P/Churyumov-Gerasimenko.
To celebrate that, Michiel Straathof has updated Mike Malaska’s classic “Distant Horizons” mosaic to show all the worlds that humans have touched.
From left to right we see the comet; the asteroid Itokawa, seen by the Japanese Hayabusa probe; the Moon from Apollo; Venus from the Soviet Venera 14 lander; Mars from the Spirit rover; Titan from the European Space Agency’s Huygens probe; and our own fair and watery world.
We see the horizon of each, a poetic and fitting tribute to our own nature of looking beyond. As each of these landings is a magnificent accomplishment worthy of our praise and awe, they are yet each still just a stepping stone, a footprint that leads beyond.
After all, as Konstantin Tsiolkovsky, father of rocketry, has often been quoted:
“The Earth is the cradle of humanity, but one cannot live in the cradle forever.”
Last week, the European Space Agency landed a space probe on a comet. It was big news—historic, even.
But another event caused a stir at the same time, tangentially related to the event. Matt Taylor, the Rosetta mission’s project scientist, went on the air to talk about the successful landing. However, his choice of attire was unfortunate.
He was wearing a bowling shirt covered in pinup-style drawings of scantily clad women.
This upset a lot of people. A lot. It was compounded by his extremely poorly thought-out description of the difficulty of the Rosetta mission: “She’s sexy, but I never said she was easy.”
Yikes. To be clear, I don’t think Taylor is a raging misogynist or anything like that; I think he was just clueless about how his words might sound and his shirt might be interpreted. We all live in an atmosphere steeped in sexism, and we hardly notice it; a fish doesn’t notice the water in which it swims. I’ve lived in that environment my whole life, and I was well into adulthood before I started becoming aware of it and figuring out how to counter it. I’m still learning.
Importantly, the next day, clearly upset he had caused such a fuss, Taylor apologized on air sincerely and graciously for his actions. For the most part, the people who were upset accepted his apology and moved on.
But it doesn’t end there. As you might expect, when people complained about the casual sexism of the shirt and the mission description, a frothing torrent of backlash misogyny swept over social media, another in a long line of demonstrations of Lewis’ law (“Comments on any article about feminism justify feminism.”)
There is much I could say here, but Dr24Hours wrote an excellent summary that aligns fairly well with my thinking. Please go read that right now.
But I have something to add.
If you think this is just women complaining, you’re wrong. Certainly many have, and rightly so. But the fact is, I’m writing about it. I can point you to many men, friends of mine, scientists and science communicators all, who have spoken up about it. It’s important that men speak up, and it’s important that we listen, too.
If you think this is just complaining from wannabes who can’t hold a candle to someone who just landed a probe on a comet, you’re wrong. Talk to my friend, the cosmologist Katie Mack. Or the planetary scientist Sarah Horst. Or geologist Mika McKinnon. Or planetary geologist Emily Lakdawalla. Or radio astronomer Nicole Gugliucci. Or professor and science communicator extraordinaire Pamela Gay. Or Carolyn Porco, who worked on the Voyager mission and is the leader of the Cassini imaging team, the space probe that’s been orbiting Saturn for over a decade now.
If you think this is just a bunch of prudes, you’re wrong. It’s not about the prurience. It’s about the atmosphere of denigration.
If you think it’s OK to use a misogynistic gender-charged word to insult and demean a woman because she used a generic nongender-charged insult about a man, then you’re really wrong (and that’s one representative tweet from many I saw just like it).
If you think this isn’t a big deal, well, by itself, it’s not a huge one. But it’s not by itself, is it? This event didn’t happen in a vacuum. It comes when there is still a tremendously leaky pipeline for women from undergraduate science classes to professional scientist. It comes when having a female name on a paper makes it less likely to get published, and cited less. It comes when there is still not even close to parity in hiring and retaining women in the sciences.
So yeah, it’s just a shirt.
And it’s just an ad.
It’s just a saying.
It’s just a TV show.
It’s just the Internet.
Yes, but you almost make as much as a man does.
It’s just a catcall.
It’s a compliment!
It’s just that boys will be boys.
It’s just that she’s a slut.
It’s just that your dress is too short.
It’s just that we want to know what you were wearing at the time, ma’am.
It’s just it’s just it’s just.
It’s just a death by a thousand cuts. No one cut does the deed. In the end, they all do.
A few days ago, the world watched and cheered as the tiny spaceship Philae landed on the surface of a comet. However, it was quickly determined that the anchoring harpoons didn’t fire, and the lander bounced off the comet. It soared a kilometer high before falling agonizingly slowly back down nearly two hours later, only to take a second, shorter hop, ending up in comet incognita.
It took a little while, but images taken by the orbiting Rosetta spacecraft mothership (and assembled into a short video) were released by the European Space Agency showing where Philae impacted the first time. The video shows before-and-after images of where Philae smacked down. At the time, my friend/planetary geologist/Planetary Society blogger Emily Lakdawalla speculated that you could actually see Philae and its shadow in the “after” image, but the data were so noisy I was pretty skeptical.
Turns out, she was right*.
Here is a lovely animated gif showing the two images, with the impact site marked in the first image, and the lander (with shadow) in the second.
[Photo by ESA/Rosetta/NAVCAM; pre-processed by Mikel Canania]
Amazing! Astrophysicist Eamonn Kerins did this even better: He made a “difference image”, subtracting one from the other to show what’s changed between the two. It really brings out Philae and its shadow:
You can see lots of bright pixels — most likely “hot pixels", overactive spots on the camera detector — with dark ones next to them, a product of how the images were processed. Note how the spot labeled as Philae is blurrier, and the shadow is several pixels below it. That’s pretty convincing to me.
I was initially skeptical because the “plume” stretching below and to the right of the impact site looked the same in both images, and was also mimicked by a similar feature to the upper right; both look like ridge shadows.
In the difference image those go away, so most likely they really are shadows, the lower one coincidentally right on top of where the lander bounced. That’s unfortunate, since it steered me away from what was really happening.
And as a reminder of what you’re seeing: That’s an action shot of a 100 kilogram machine the size of a lounge chair that weighs less than an ounce in the local gravity hitting the surface of a four kilometer wide dirty snowball almost precisely on target as seen by another spaceship that took ten years and three planet flybys to achieve its goal of matching the 40,000 kph velocity and entering orbit around a comet… all of which is a first for humanity, ever.
So yeah. Cool.
* At least she was gracious in victory.
Not long ago, the ridiculously huge sunspot called Active Region 2192 ruled the face of the Sun. Bigger than Jupiter, it was easily seen by the (adequately protected) naked eye, and it was a distracting though extremely cool blemish during October’s solar eclipse.
A sunspot that big has a lot of storage space to stuff magnetic fields, and 2192 didn’t disappoint. Sunspots are essentially magnetic phenomena, and as the huge looping magnetic field lines in the spot tangled up, they sometimes violently snapped and reconnected, releasing their energy as solar flares. Dwarfing every nuclear bomb on Earth combined, the flares kept popping off as 2192 marched across the Sun’s disk, swept along with our star’s rotation.
From space, the Solar Dynamics Observatory keeps a close eye on the Sun, and watched in multiple wavelengths (think of them as colors) as 2192 did its thing. James Tyrwhitt-Drake, who has created interested scientific animations before, took 17,000 SDO images of the Sun in the ultraviolet, spanning Oct. 14 – 30, 2014, and created an astonishing video that shows 2192 in all its glory. The video is available in 4k resolution, if your bandwidth can choke that down, but it’s worth it to make this full screen:
The sound you hear is not real; it’s made from visible light data by SDO’s Helioseismic and Magnetic Imager, which maps motions on the Sun’s surface, which was then converted into sound by solar astronomer Alexander Kosovichev.
In this view, south is up, so the Sun rotates right to left (I’m used to it the other way, but hey, in space there is no up, so fine). 2192 makes its appearance early on, announcing its presence with towering loops of magnetic energy over 200,000 km high — mind you, the Earth is a mere 13,000 km across — and dominates the view thereafter. It’s incredible.
You can watch as enormous prominences erupt away from it, hot hydrogen gas flowing along otherwise invisible magnetic field lines like beads on a wire. The gravity of the Sun is strong, and pulls the gas with a force nearly 30 times stronger than Earth’s gravity, but the magnetic field is strong, too, and the gas flows back to the Sun along curving, graceful paths. It’s mesmerizing.
As the Sun rotates, AR 2192 has come around again, returning on or about Nov. 12. But it decayed substantially when it was on the far side of the Sun from the Earth. It’s a shadow, so to speak, of its former self. It doesn’t look like it’ll last much longer. We may not get another spot like it for a long time; it was the biggest seen in decades. But the Sun is a complex beast, and predicting its behavior for things like this is a losing bet. We may not see another like 2192, or another might grow and swell into existence once again. We’ll have to wait and see.
One of the funny things about being a human is that our intuition can steer us wrong, even on things that should be pretty obvious, things we see literally every day.
For example, if you ask someone what would fall faster, a bowling ball or a marble, I bet a lot of folks would say the heavier bowling ball falls faster. But in fact, if dropped from a meter or so off the ground, they’d fall at the same rate. Gravity accelerates them at the same rate, so they fall at the same rate.
Part of the reason our intuition is off here is due to air. As objects fall, the air pushes back on them. This depends pretty strongly on their surface area, how big they are, so a lightweight large object will in fact fall more slowly than a heavier, smaller one.
Dropping a bowling ball and a feather will yield results that will satisfy our intuition. But what if you removed all the air from the room and dropped them? What happens then?
My friend and physicist Brian Cox did just this for his new BBC TV series Human Universe. He traveled to NASA’s Space Power Facility at the Glenn Research Center in Ohio to test gravity. What happens when he does is pretty wonderful.
Lovely! With the air removed, the feathers and ball fall at the same rate, just as Galileo predicted and Newton showed mathematically. I assume the bit at the end of the video about Einstein is referring to the Equivalence Principle, which has to due with acceleration due to gravity—if you’re standing on the Earth’s surface, you feel this as your weight, the force due to Earth’s gravity on your mass—and is indistinguishable from acceleration due to some force (like being in a rocket under power). This idea has profound implications, and in part led to Einstein developing the theory of General Relativity. I’d love to see this show and find out how Brian follows that concept farther.
Update (Nov. 14, 2014 at 23:00 UTC): Contact with Philae has been re-established! Data taken from the surface (including drill samples) have been sent back to Earth. Not only that, a command was sent to rotate the lander, and that worked as well! It rotated by 35°, enough to point a bigger solar panel up to the Sun. Reports indicate power is flowing, so the life of the mission has at the very least been extended somewhat. This is incredible work by the ESA team!
Update 2 (Nov. 15, 2014 at 00:00 UTC): While the move to rotate the lander was successful, the drain on the battery by the instruments on board was too much. At about half past midnight the voltage dropped below the critical point and the lander put itself into standby mode (no science being done; just communication with the Rosetta orbiter). HOWEVER, the point of the rotation was to get more power available. It's entirely possible that over the next few days, as the comet rotates around, enough sunlight will hit the solar panel to the battery enough charge to restart Philae. As usual, Emily Lakdawalla has more info on this. So Philae is not necessarily dead. It may just be sleeping, hibernating. We could very well hear from it again.
The European Space Agency just released a great short video showing Rosetta's view on the comet where the Philae lander took its first kilometer-high bounce!
If I've measured this correctly, the red circle is roughly 15 meters (50 feet) across. The "flight dynamics solution" is where the spot was predicted to be given Philae's trajectory, and as you can see they pretty much nailed it.
It's hard to interpret exactly what we're seeing in the before and after. The dark streak looks like a plume of material, but I'm not so sure. Just above and to the right you can see another similar dark feature, and I'm leaning toward them both being shadows cast by low ridges as the angle to the Sun changed between the first image and the second.
These images should prove useful in figuring out just where Philae is; its location is still unknown. As I write this we're still awaiting word that contact between the still-orbiting Rosetta and the lander has been re-established, and the data taken uploaded. Hopefully, samples of the comet have been analyzed by Philae, and we'll get a sense of what materials are on and just below its surface.
This is still very exciting! Certainly, it would've been far better had the lander stayed upright, and able to draw energy from the Sun, but even if that's not to be, it's still done an amazing job.
There’s more news this morning about Philae, the European Space Agency lander that is on the surface of the comet 67P/Churyumov-Gerasimenko. Recap: It set down on the comet yesterday, but the harpoons didn’t deploy. It bounced, twice, and came to rest a kilometer or so from the desired landing site. It’s not known precisely where it is, and it’s too small for the Rosetta spacecraft, still orbiting the comet, to easily find it.
Update, Nov. 14, 2014 at 18:00 UTC: The ESA Rosetta blog has posted an update, which has information about what the instruments on Philae have been doing so far.
Philae came to a rest on its side, unfortunately in a hole or an area surrounded by tall outcroppings. Because of this it’s not getting enough sunlight for its solar power cells to keep it charged. It has two batteries, but the instruments are using up that power rapidly. If nothing is done, it will run out of power soon.
If it does run out of power, all is not necessarily lost; as the comet nears the Sun the cells may receive enough charge to turn the lander back on. This is speculative, though.
The good news is the lander is working and taking data; dozens of high-res photos have been taken, for example, and are waiting to be transmitted up to Rosetta so they can be sent back to Earth. Contact between Rosetta and Philae is intermittent as the orbiter moves around the comet and the line of sight clears to the lander. The next good pass should be today around 21:00–23:00 UTC (16:00–18:00 Eastern).
I wondered yesterday if outgassing from the comet could dislodge Philae, but apparently it’s too dense for that to happen. One idea engineers are looking into is turning on the lander’s flywheel (a heavy, rapidly rotating disk that is used to rotate the lander)—Lander Manager Stephan Ulamec calls it “a very attractive idea”—which might provide enough torque to get Philae upright. There may not be enough power to spin it up though.*
I get the impression that, of course, people on the Philae team are disappointed at what happened, but are still really happy that it worked at all and got as far as it did. I keep hearing comments that anything they get now is “cream on top” of the amazing data they’ve already received. In other words, this mission was a success!
Let’s hope that the success it’s had so far is just the beginning, and not the end. And remember: Rosetta is still orbiting and going strong. That part of the mission has many months of discovery ahead of it.
*Correction, Nov. 14, 2014: This post originally misspelled the first name of Stephan Ulamec.
I’m about to make you very happy. Stop what you’re doing and watch this extremely cool video called “Cymatics: Science v. Music”, by musician Nigel Stanford. Seriously. Make it high-def, full screen, and crank up the volume.
There are a couple of things I want to point out in particular. I laughed out loud when I saw the drummer’s spiraling water (starting around the 1:20 mark). His drumming makes the rubber tube vibrate in a circular motion, which sends the water flow out in a different direction over time, like a lawn sprinkler. You don’t see the hose move because the vibration is synched with the video frame rate; every new frame of video is taken when the hose is back to the starting position. I explain this in great detail in an earlier post about this effect (you really do want to see that post; it’s got very cool stuff in it).
I like the way the flames move starting around 3:30, too. There’s a speaker at one end of the gas tube, and as sound waves come out of it the gas in the tube gets compressed and rarefacted (the opposite of compression, so decreasing the density of something) by the waves. Standing waves are created in the gas, like the waves you get if you snap a rope at just the right rate. That’s why you see the flames going up and down in those graceful sine curves.
And I love the patterns of sand on the metal plates seen throughout the video. That’s an interference effect. Waves of sound travel through the plate, making it vibrate. Where the crests of those waves meet each other you get amplification of the waves, again related to standing waves. The patterns are complex because of the shape of the plate; the waves propagate through it and get their direction and shape changed by the edges and corners of the plate. I remember working through the math of this in my grad school mechanics physics class; it took days and many, many sheets of paper to solve the equations even to show how a circular drumhead vibrates, which is a pretty simple shape.
But out of complexity can come great symmetry and beauty. The patterns are lovely.
And Tesla coils? C’mon. They may be the single coolest thing ever invented.
I really like Stanford’s music, too. The video was sent to me by Tom Lowe, an astonishingly talented astrophotographer. Lowe created the time-lapse videos “Rapture”, “TimeScapes”, and “Death Is the Road to Awe”, which are all stunning. Stanford did the music to “TimeScapes”, which is how this is all connected.
I can’t get enough of stuff like this. Astronomy, physics, science, math, music, video… they are all related, and the interconnectivity is, simply, art.
Yesterday, the Philae lander separated from the Rosetta spacecraft, descended to the comet 67P/Churyumov-Gerasimenko, and then … what, exactly?
It was supposed to fire harpoons, reel itself down to the surface, then engage screws in the bottom of its landing legs to secure itself to the surface. However, the harpoons didn’t fire. Yesterday we knew it bounced, and landed somewhere else, but now we’ve learned more.
First of all, it actually bounced twice! It probably hit, then rebounded nearly a kilometer off the surface in the tremendously low gravity—on the comet it weighs about as much as 10 grams would on Earth, the same as four ping-pong balls. The comet rotated underneath it, and then the lander slowly hit again some distance downrange, only to rebound again. This was a much lower bounce, perhaps 20 meters (60 or so feet) high, and didn’t last nearly as long, only about seven minutes.
Where did it land? It’s not clear. In the image above it hit in the red square, its original landing site, then bounced to somewhere in the blue diamond hundreds of meters away. There is a large, shallow crater on the top of the smaller of the two lobes of the comet (what looks like the rubber ducky’s head in the original pictures of the comet showing its shape) and it’s most likely in there somewhere. The high-resolution camera OSIRIS on Rosetta itself is busily taking images of the area to see if the lander can be spotted.
The bad news is it isn’t upright. It’s on its side, with one leg sticking up “in the air”—really into space, since there’s no air on the comet. The good news is that the folks at the European Space Agency are still in contact with Philae, and it’s sending back data, including pictures.
And the first one sent back (at the top of this post, and enlarged above) is dramatic, showing the weird, forbidding landscape. The lander appears to have come to against a flattish surface of some kind. The angle is confusing, since we know the lander is on its side. The picture was taken by the CIVA camera near the top of the barrel-shaped lander, and it looks down on the foot. Judging from the orientation here, this means we may be seeing the highly angular surface of the comet, though it could be a wall or side of a cliff. The material looks more solid, not powdery and soft, which might explain the lander bouncing.
The lighting is worrisome; if the lander is in shadow for long periods of time the frigid cold might affect it, and the solar panels may not be able to supply enough energy. Hopefully at the next ESA press conference they’ll be able to fill us in on that situation.
So while this isn’t ideal, let’s keep in mind the real situation and what we’re seeing here: The Philae lander is down, on the surface of a comet, it’s working, sending back data, and will still be able to carry out much of its mission.
That counts. This mission was already a success yesterday, and now everything we get back from it just makes things better.
I remember when I was in grad school, running a telescope observing lab. I was setting up the telescopes, and Jupiter was well placed in the sky, so I was using it to align the finderscopes and get things focused. By coincidence, one of its moons, Io, happened to be just on the edge of Jupiter’s broad face when I looked. Over the course of the three hour lab, we all took turns going back to that ’scope to see how much Io had moved. By another sheer coincidence, Io takes about three hours to cross Jupiter’s disk, so the transit ended just as the lab did.
It was mesmerizing. But it was nothing like this:
That’s how Hubble sees Jupiter, which is way better than my old (otherwise very nice) 25 cm ’scopes did. You can see the broad bands and swirly festooned storms all over its cloud tops. But what really gets you is the ridiculously huge Great Red Spot, big enough to swallow the Earth.
And as if even that isn’t cool enough, there’s a big black spot on it: That’s the shadow of the moon Ganymede, which happened to fall right across the Spot when the shot was taken.
Jupiter’s moons orbit the planet above its equator, and Jupiter has almost no axial tilt (unlike the Earth, where our spin axis is tipped about 24° to the plane of our orbit). That means Jupiter’s moons pass directly between the planet and the Sun every orbit, casting their shadows on the clouds (Jupiter doesn’t have a solid surface; we only see the top of its dense atmosphere, which is tens of thousands of kilometers deep).
I’ve seen moon shadows on Jupiter many times through telescopes, but I’ve never seen one throw its shadow over the Spot! That’s really cool. And what really strikes me is how big Ganymede’s shadow is compared with the Spot. There are two reasons for that: One is that Ganymede is big, 5,270 km across—bigger than the planet Mercury! So it casts a huge shadow.
But also, the Great Red Spot over the years has become somewhat less Great. It’s shrinking. In the past 40 years it’s lost more than 30 percent of its width, and no one knows why.
Incidentally, another mystery is why the Spot is red. Is it from material upwelling from deep within Jupiter's atmosphere, or is it from something else? A new study indicates that it might be due to gases and other material in the upper atmosphere of the planet that get smacked by solar ultraviolet light, changing their chemistry. In the lab, such a process has created a red gas similar to what's seen in the Spot. I can't say if it's conclusive, but it's an interesting step in solving this long-standing enigma.
Anyway, the picture above, released the week of Halloween, was being sold as “Spooky Shadow Play Gives Jupiter a Giant Eye.” I am a master observer of pareidolia, and I’m not buying this. It looks a little like an eye to me, but the placement and relative dimensions don’t look right. If pressed, I’d say it looks more like a jovian belly button.
So maybe, instead of using Hubble, they should have taken this picture with the Naval Observatory.
Today, Nov. 12, 2014, at 16:02 UTC, a tiny robot landed gently down onto the surface of a comet.
Five hundred million kilometers away, millions of humans on Earth rode along with it.
After 10 years of travel through the depths of space, and at least that long beforehand filled with meetings, designs, construction, and a launch in 2004, the Philae spacecraft was successfully released from its Rosetta mothership. Then, seven hours later, it made history.
We have flown by eight comets before, impacted one with a 370 kilogram block of copper, and, now, for the first time ever, have landed on another. The robotic proxy of humanity sits on the surface of the comet 67P/Churyumov–Gerasimenko.
But only barely. For reasons yet unknown, the harpoons failed to deploy, so the lander may not be firmly anchored in place. In fact, from the telemetry received, it appears to have slowly hit the surface, bounced, spun a bit as it was over the surface (possibly due to the rotation of an internal flywheel used to change the attitude of the spacecraft), then landed again.
But it is down, and very nearly in the center of the planned target area. And if only for this reason, the mission has been a success.
It’s difficult to overstate this achievement. The comet is moving on an elliptical orbit that takes it just outside the orbit of Jupiter (850 million kilometers from the Sun) and as close as 186 million km sunward (just inside the orbit of Mars). The Rosetta spacecraft had to travel for a decade through space to catch up to its target, flying past two asteroids—Lutetia and Steins—as well as getting a gravitational boost by swinging past Mars and even Earth. It was a long, cold journey, which finally brought it alongside 67P in August 2014.
After that it slowly approached the comet, taking mapping images along the way, searching the bizarre terrain (cometain?) for a landing site. After much deliberation a suitable site was chosen. Rosetta moved in, dropped Philae, and the rest is history.
Except, again, we’re still waiting for more information. Philae is definitely down, and definitely working. It returned a few images, and engineers are still receiving telemetry from it. But it’s not clear what will happen next. The gravity on the comet is terribly weak—about 0.01 percent that of Earth—and the lander weighs half an ounce on the surface. That wouldn’t be a problem in the vacuum of space, except the comet is outgassing: The ice on and below the surface is warming as the comet approaches the Sun, and turns directly from a solid into a gas. This is a gentle wind, to be sure, but when you weigh less than a sheet of paper does on Earth, it doesn’t take much to set you flying again.
Philae has screws on the bottoms of its landing legs, and they did appear to deploy, but it’s not known how well the lander is secured. Nothing is clear right now. The European Space Agency held a press conference to give an update, but it won’t be until tomorrow that they know enough to take the next step. As soon as I know, I’ll let you know.
But, despite this sobering news, there is still joy and wonder to be had. The technical prowess to achieve this landing is nothing short of awe-inspiring. Math, science, engineering, even management and teamwork—in this case, across many countries in Europe—produced a breathtaking result: We have sent our work and our minds and our hearts across space, and done something truly remarkable.
Congratulations to ESA, to everyone involved with Rosetta, and yes, to all of us who care about exploring the Universe. It’s one of the noblest things we do.