Bad Astronomy Blog

As the Earth Turns

Fri, 11/21/2014 - 04:30

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.

Categories: Astronomy Headlines

“Happy 10th Anniversary in Space,” He Said Swiftly

Thu, 11/20/2014 - 04:00

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.

* I wrote about this for my book Death from the Skies!, and/or you can read more about it here

Categories: Astronomy Headlines

What Exploded Over Russia This Time?

Wed, 11/19/2014 - 04:30

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.

Categories: Astronomy Headlines

Distant Horizons

Tue, 11/18/2014 - 04:30
“Ah, but our reach should exceed our grasp, Or what are the heavens for?”
 — 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.”

Categories: Astronomy Headlines

Shirtstorm

Mon, 11/17/2014 - 10:05

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.

Categories: Astronomy Headlines

Philae Spotted Hopping Away in Photo of Comet

Mon, 11/17/2014 - 04:30

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.

Categories: Astronomy Headlines

Epic 4K Sun Video, with Bonus Sunspot Tantrums

Sun, 11/16/2014 - 06:46

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.

Categories: Astronomy Headlines

Hey, Galileo Was Right!

Sat, 11/15/2014 - 04:30

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.

I’ve known Brian for quite some time, and I have to say it’s nice to see him finally get some recognition for his work. The poor guy has been languishing in obscurity for years

Categories: Astronomy Headlines

Rosetta Spots Site of Philae’s First Bounce

Fri, 11/14/2014 - 14:06

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.

Categories: Astronomy Headlines

Quick Philae Update

Fri, 11/14/2014 - 09:38

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.

Categories: Astronomy Headlines

Cymatics: Science v. Music

Fri, 11/14/2014 - 04:30

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.

Science! Music!

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. 

Categories: Astronomy Headlines

COMET UPDATE: Where is Philae?

Thu, 11/13/2014 - 08:03

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.

Categories: Astronomy Headlines

Shmutz in Jupiter’s Pupik

Thu, 11/13/2014 - 04:15

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.

Categories: Astronomy Headlines

When We Reached Out Into Space and Grasped a Comet

Wed, 11/12/2014 - 12:12

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.

Categories: Astronomy Headlines

Watch Humanity Touch a Comet

Wed, 11/12/2014 - 03:00

At approximately 16:03 UTC (11:03 Eastern) Wednesday, Nov. 12, for the first time in human history, a spacecraft is expected to physically land on a comet.

As I write these words, less than a day before the event, the lander Philae has not yet separated from the Rosetta probe. As you read these words—and assuming no roadblocks messed things up—that should have occurred on or about 09:03 UTC (04:03 Eastern time). Philae will then slowly approach the comet 67P/Churyumov-Gerasimenko, taking data and images along the way, and at the right moment will fire harpoons into the comet's surface and then reel itself down. 

These events happen over night for most of the United States, making it difficult for me to cover everything live. So first, I suggest following my friends Emily Lakdawalla and Karl Battams on Twitter; they are at Rosetta HQ and tweeting everything as they hear it. Emily has posted a very useful timeline of events as well.

Second, I'm embedding a live feed from the European Space Agency. It's not clear when new images will be released, but if you're up you might get a chance to see them. I plan on getting up early so I can find out what's what, and when I do I'll update this post. Think of this as a placeholder until then. But stay tuned! I'll have images as soon as I can get them.

And remember, the times listed here are approximate, so you might want to tune in early so you don't miss anything!

Categories: Astronomy Headlines

The Dark Side of a Comet

Tue, 11/11/2014 - 08:00

Every now and again, I think it's OK to simply post an amazingly dramatic and moody photo of an astronomical object. So please take a moment to appreciate this portrait of a brooding comet:

This is 67P/Churyumov-Gerasimenko, the double-lobed 10 billion ton chunk of ice and rock that is currently the flame to the ESA Rosetta spacecraft's moth. The images we've seen so far have been well-lit by the Sun, but this one was taken when the comet was between the probe and the Sun. With only the illuminated limb of the comet visible, how is it we can still see some features in the dark landscape? 

Comets are not static; they change. As they approach the Sun, the ice vaporizes, releasing dust. This dust scatters the sunlight, providing a soft glow that fills in a bit of the gloom. 

Rosetta was only 19 kilometers from the comet when this picture was taken. That's a whisker's width; when I go bicycling in the summer, 19 km would be a fun jaunt.

The spacecraft is so close because it's gearing up for history: Tomorrow, Nov. 12 at 16:03 UTC (11:03 Eastern), the Philae lander will touch down on the surface of 67P, the first time such an attempt has ever been made. As usual when it comes to solar system encounters, Emily Lakdawalla has what you need to know about the landing

I'm very excited about this. We've slammed a probe into a comet before, but we've never soft landed on one. The images will be stunning, I'm sure, and this is an entirely new type of world we've never seen in such detail. This will be quite an adventure.

Categories: Astronomy Headlines

When Worlds Collide, Rings Follow

Tue, 11/11/2014 - 04:00

A few days ago I posted a spectacular picture of a protoplanetary disk, a sprawling multi-ringed wheel of gas and dust swirling around a young, nearby star. I mentioned I had studied such objects before; it all started in the late 1990s when I was working on a Hubble Space Telescope camera called STIS. An astronomer named Carol Grady had observed several such disks around stars, and I helped calibrate and process the images.

And by coincidence, new Hubble images of several similar structures was just released… taken by STIS!

Quite the menagerie. Each image shows a ring around a different star, and the fierce light of the stars themselves has been blocked out so it doesn’t blow out the much fainter light from the rings.

However, unlike the disk image I wrote about last week, these are not protoplanetary disks. They’re dusty debris remnants, shaped more like rings than disks, probably caused by collisions of asteroids and/or comets (some of them quite large) orbiting these stars after planetary formation has already been well underway. In other words, these are somewhat older structures from 100 to 350 light years away.

What’s striking are the weird shapes. You might expect they’d be circular, symmetric, and flat. But they are anything but! The ring seen edge-on around HD 32297 appears to flare, like wings, as does the one around HD 61005. My first thought was that they’re moving through space, plowing through the thin material between the stars. That would blow the rings back a bit, warping them. The analysis done by the team that took the images agrees.

I was also struck by the asymmetry in the ring around HD 181327. Elliptical rings are usually actually circular, but we see them at an angle (like the rim of a drinking glass can look like an oval). But this ring is distorted, thicker and brighter on one side. If it’s from the collision of two objects, they must have been pretty large, and what’s left of the two bodies is probably in that larger thicker part, with the debris having spread out around the star. The ring is about 13 billion kilometers in radius (about three times the distance of Neptune to the Sun), which is pretty weird: You’d think space would be fairly empty that far from the star, and collisions rare. But there it is.

Interestingly, the inner edge of the ring is pretty sharp, when it would be expected to be fuzzy. That means there may be a planet too faint to see in these images, orbiting inside the ring, and gravitationally clearing out the debris closer to the star.

Clearly, other young solar systems have all sorts of behavior problems, and no two appear to be exactly alike. While that makes them somewhat harder to study (it’s nice to be able to categorize objects using similar characteristics) it also makes this more exciting. Surprises are always fun.

And it pleases me greatly to know that not only were these observations made using my old camera, but they were also taken by my old friends Glenn Schneider and the aforementioned Carol Grady, along with a handful of other astronomers with whom I worked in my Hubble days. It’s nice to see good scientists still doing good work.

Categories: Astronomy Headlines

Weightless Water Sports

Mon, 11/10/2014 - 09:00

Recently, space station astronaut Reid Wiseman fell back to Earth riding a trail of fire as his Soyuz capsule rammed through the air. But shortly before he returned to the ground, he and his crewmates took some time while in space to play with… water.

In the weightless conditions of orbit, water behaves differently than it does on Earth. With the space station and all inside falling freely around our planet, other forces dominate the water’s actions, which provides for some eerie, cool, and very fun videos.

Like this one:

Weird, isn’t it? The two drops of water are floating, and for a moment after they touch nothing happens, until they suddenly merge into one, bigger blob.

They resist merging due to surface tension. I describe this in detail in an earlier post about water in space, but in short, the water molecules on the surface of a drop feel a weak electromagnetic force inward, toward the center of the drop, because water molecules are slightly asymmetric. The outside of the drop has an overall (though faint) positive charge. When two drops touch, that positive charge on each initially resists the other drop, like the north poles of two magnets repelling each other. But if they’re moving at the right speed, their own momentum overcomes that weak resistance. The water molecules in the drops rearrange themselves, and you get one bigger blob.

I love how the resulting blob moves! The water flows around inside due to the momentum of the collision, which settles down after a few seconds as surface tension and friction take over.

However, not every collision results in a merger. If you set up things just right, the repulsion between drops wins:

What I like most about that video — besides the droplets splattering around the bigger drop if their velocity is too low to overcome surface tension — is what looks like a second droplet inside the big drop. But that’s not water. It’s air.

I’ll let Expedition 31 astronaut André Kuipers demonstrate:

Kuipers injected a bubble of air into that drop of water, and without gravity acting on it, the air is free to move around inside the drop. The water in the drop acts like a lens, flipping the image of his face over, and the air bubble does the same thing, so inside that we see him right-side up. Neither the bubble nor the drop is perfectly symmetric, so the images are distorted.

I find this kind of stuff fascinating. I mean, we know how the science works, but to see it in action is delightful (and it’s not always obvious what will happen even when you know the science). The astronauts were clearly having a great time filming this; here’s a video of them playing with the water (note: this was recorded using a 3D camera; you’ll need red/green glasses to see it at its best, and I do recommend watching it that way!):

There isn’t enough money in the world to get my butt in a rocket and blast me off into space. I get sick if I read in a car. But videos like this make me regret my weak stomach and stuffy sinuses. This really does look like a lot of fun.

Categories: Astronomy Headlines

Announcing Crash Course Astronomy!

Mon, 11/10/2014 - 04:00

I’ve been hinting for some time about a secret project I’ve been working on, and the time has finally come to announce it:

I’m writing and hosting an online astronomy video series!

The series will air on the PBS Digital Studios YouTube network starting in January, and — get this — is done as part of Hank and John Green’s Crash Course video series.

Yes, that Hank and John Green, the Vlog Brothers. Hank approached me about it last summer, and we quickly worked out the details. I recently started writing the episodes, and the first few will be filmed extremely soon.

Regular readers may remember I visited Hank in his Montana fortress of solitude last August, and filmed a special episode of SciShow about how we know the distances to stars, as well as a SciShow episode about the smallest known star in the Universe. Of course, that’s all we told the public. Behind the scenes we were plotting and hatching our nefarious scheme.

I’m really, really excited about this. I’ve been a fan of Hank and John for a while, and this is something I’ve been wanting to do for a long time. They have an excellent production system, and I know this is going to be a lot of fun.

Along with Crash Course Astronomy, there’s going to be a new U.S. Government series hosted by Craig Benzine (aka WheezyWaiter). I know, you’d think he’d be doing a chemistry series, but Hank already had that covered.

In fact, Hank made a video describing how all this works (the good part starts at 2:43).

I’ll keep y’all posted when the time nears for the premier. In the meantime, you can read more about all this at re/code. You can also support Crash Course at Subbable.

Thanks, and see you on YouTube!

Categories: Astronomy Headlines

Expedition 41 Set to Return to Earth Tonight

Sun, 11/09/2014 - 09:00

Tonight (Sunday night/Monday morning) at 00:31 UTC (21:31 Eastern), a Soyuz-13M space capsule will undock from the International Space Station. After moving away from the facility, it will begin a de-orbit burn, ram through Earth’s air, and then land in Kazakhstan three hours later, scheduled for 03:58 UTC. On board are three astronauts: American Reid Wiseman, Russian Maxim Suraev, and German Alexander Gerst.

You can watch the procedure live on NASA TV, as well as NASA’s Ustream channel (embedded above). The European Space Agency will also stream it. Actually, I love the line they use to describe the journey: “Their three-hour trip back to Earth will reduce their speed from 28 800 km/h to zero.”

Hard to argue with that. It’s succinct.

When the astronauts close the Soyuz-13M hatch behind them, Expedition 41 will officially end, and Expedition 42 on board the ISS begins (which is how the numbering generally works). 42 will then consist of three astronauts who have been on board since September, and they’ll be joined later this month by three more astronauts when that trio launch aboard a Soyuz to ISS. SpaceFlight101 has a good overview of Expedition 41.

Categories: Astronomy Headlines

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