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Posted by Phil Plait

Oh, I love stories like this: “Citizen scientists” —people who are not necessarily trained scientists but are enthusiastic and eager to take part in scientific research— have discovered a brown dwarf near the Sun. They examined data taken by an orbiting observatory and found the little beastie right at the edge of the telescope’s detection capabilities.

OK, first: Simply put, a brown dwarf is an object that is in between the mass of a planet and a star. That’s really too simply put; we’re talking about a rich and diverse class of objects, every bit as varied and interesting as planets and stars themselves (for that reason, I think it’s unfair to call them “failed stars,” as some do; they are their own thing, and fascinating in their own right). You can find out a lot about them by watching my brown dwarf episode of Crash Course Astronomy:

Being warmish, brown dwarfs tend to emit most of their light in the infrared part of the spectrum, outside the color range our eyes can see. But we can build detectors that are sensitive to infrared, attach them to telescopes, launch them into space, and sweep the sky to see what’s out there.

Astronomers have done this, many times, including with the wonderful Wide-field Infrared Survey Explorer, or WISE, for several years starting in 2010. It looked in four different wavelengths (colors) of IR light, creating a vast catalog of objects in the sky — over three-quarters of a billion of them.

A lot of those objects were brown dwarfs. They were found in two ways: Either by their colors (they tend to emit light at a specific IR color, making them stand out in WISE images) or by their motion. Brown dwarfs are extremely faint, so we only see ones that are relatively nearby the Sun (like, out to 100 light-years away or so). Because they’re close, their motion in space as they orbit the galaxy means we can see them move over time … it’s just like nearby trees seem to whiz past you when you’re in a car, when more distant object appear to move more slowly. Finding moving brown dwarfs is hard; they’re faint and look little more than blips in the images. This makes automating the search difficult (computers are easy to fool). But the human eye is good at seeing such things! And such a task doesn’t need a lot of training, either.

star sizes to scale

Size comparison of a normal star like the Sun, a red dwarf, a brown dwarf, and Jupiter. Credit: NASA's Goddard Space Flight Center

That’s why the folks at Zooniverse decided to take this on. This is a group of astronomers and researchers who figured out that non-scientists can not only participate in scientific research but also give a meaningful contribution to it as well. They collect data in the public domain (quite a bit of astronomical data) and present them in such a way that people can analyze them through simple tasks. For example, Galaxy Zoo asks people to identify spiral galaxies and determine whether the arms open clockwise or counterclockwise. Simple, fun, and oddly addictive, in fact. I’ve identified hundreds of galaxies myself there, and they’ve published quite a few papers on the results.

They did a similar project with the WISE images. Called Back Yard Worlds, it blinks four images from WISE observations taken of the same part of the sky at different times. The images have been processed a bit, subtracting one from another, so that fixed objects like stars and galaxies are suppressed, hopefully leaving behind moving targets. Your task: Look for the things that change. It’s not easy; I just tried it and there are lots of things that can fool the eye. But if enough people look at enough images, things turn up.

brown dwarf animation

Animation showing the very subtle motion of WISEA J110125.95+540052.8 in the four WISE images. Credit: NASA / WISE

And something did: On February 1, 2017, less than a week after the launch of Back Yard Worlds, a user spotted what looked like a slowly moving object. It appears as a “dipole,” a shifting spot of black and white due to the way the images were subtracted from one another. Two days later, another user spotted it, then three more not too much after that.

Clearly, the object was real. At this point, professional astronomers used NASA’s Infrared Telescope Facility, a 3-meter telescope in Hawaii, to observe the object, and they quickly determined it was indeed a brown dwarf.

It has been dubbed WISEA J110125.95+540052.8 (after its coordinates in the sky), and it’s about 110 light-years away. Not much is known about it except that it has a spectral type of T5.5, meaning it’s an intermediate mass and cool brown dwarf (with a temperature of very roughly 650-1250°C, much cooler than the Sun).

Brown dwarf before and after

Two WISE observations (each composed of several images added together) taken five years apart show the motion of the brown dwarf. Credit: Kuchner et al.

This is exciting for many reasons. For one, finding a single brown dwarf in the data implies that there are more to be discovered; the researchers estimate that more than a hundred previously undiscovered brown dwarfs should be hiding in the WISE data, waiting to be found. A half dozen or so of them may be Y dwarfs, the very coolest kind seen: Some are no warmer than room temperature!

Another reason is that I love that the public gets a chance to get their feet wet with real data. This isn’t some simulation, or some overly simplified homework assignment. This is real science, with real data, that could have a real impact. And in this case, it did, and will continue to do so. It’s wonderful that non-scientists, laypeople, can have the chance to participate in that.

And finally, there’s the potential of this. There is a lot of data out there. Did you know that all Hubble data older than one year is available through an archive? It’s not like you can just grab it and discover strange, new worlds —unlike Zooniverse, CosmoQuest, and other citizen science projects, there’s a huge overhead and learning curve with Hubble data— but there are thousands upon thousands of images and spectra just waiting to be analyzed, far more than the scientists who took them could ever hope to process.

And that’s just Hubble. Cassini, the Mars rovers, Juno … there are dozens of observatories and spacecraft with data just sitting there. What treasures lie within? What discoveries patiently await us? What new kinds of objects, old objects behaving in new ways, new phenomena, have already been captured by these eyes on the sky … biding their time until human eyes gaze upon it?

This idea is thrilling. The whole Universe is out there, and you can be a part of unveiling it.

Tip o’ the dew shield to Astrobites.

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Born with a genetic visual impairment that has no correction or cure, Susan Robinson is legally blind (or partially sighted, as she prefers it) and entitled to a label she hates: "disabled." In this funny and personal talk, she digs at our hidden biases by explaining five ways she flips expectations of disability upside down.
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I still have to review Extra Virginity as well, but I actually liked that one, so it will take longer to compose….

One of the things I did get done yesterday between work, the ball game, and the Epic Sunburn, was finish a slim book of short stories called A City Equal to My Desire by James Sallis. This wasn’t a book that was recommended to me, which means I don’t have to feel bad about truly disliking it. I found it in a keyword search on the library website for books about ukuleles, and it has a short story called Ukulele And The World’s Pain, which admittedly was one of the better stories in the book despite still not being very good.

From what I can tell, he did pick the best story out of the book to develop into a novel, “Drive”, but it is very obviously unfinished in short-story form. Sallis has a couple of ongoing problems in the short story collection, one of which is that he tends to skip the vital information you need in order to know what the fuck is going on. And not in a “the blanks slowly get filled in” way, or in a “your imagination is more terrible” way (though there is a little of that) but just in a way where like…he says something that you understand to be vital to the story but which is missing context, then spends like a page describing the fucking diner someone’s sitting in, and by then any context forthcoming doesn’t get linked back. It’s like being in the middle of a paragraph when you hit the photo plates in an older book – yes the photos are very interesting thank you but I need to finish the thought you were sharing with me before I go back and look at them. I think maybe he thinks this is challenging the reader but it’s not, it’s just annoying and makes what are otherwise interesting premises totally opaque. I shouldn’t need to work this hard for a story about a hit man who decides not to kill a politician. 

If the book had a more cohesive theme in terms of the stories, it might be more readable – he clearly enjoys building worlds and then doesn’t quite know what to do with them once he’s built them, so if this was an entire book of “weird and different worlds” ala Italo Calvino’s Invisible Cities, I would buy in more fully and I think he would have put a little more elbow in. But it’s not. It’s mostly “here’s a really interesting world and a person living in squalor in it does something while being in it”. Also he appears to be fascinated by describing things that are shaped like pi. And a lot of times it feels like he read a wikipedia article on something and wanted to share some knowledge, so he just kind of built a half-assed story around his wikiwander. 

And all of this I would probably let go if say, it was something I was noticing in a fanfic writer, or someone who was just starting out, or someone I felt was genuinely trying to get a point across. But there’s this inexplicable sense of arrogance to the collection, a sort of smugness to it that in professional writers drives me up the goddamn wall. Stephen King sometimes falls into the same trap, where it feels like the author believes they don’t have to respect their readers because they are The Writer. 

The thing about volumes of short stories is that you keep reading it because sometimes there is a real gem. And there are one or two good stories in the volume, but I don’t know if they’re worth the rest of it. 

So my review I guess is mostly me being annoyed, but it boils down to “If you like short stories in the SFF Noir genre, give it a whirl, but if you’re bored with a story none of them get better, so feel free to skip to the next one.” 

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making space to be creative

Jul. 20th, 2017 11:32 pm
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Posted by Wil

One week and about ten hours ago, I decided to step away from Twitter for a little bit. The specific details aren’t important, and I suspect that many of you reading this now are already nodding in agreement because you grok why. But I took it off my phone, and I haven’t been to the website on my desktop since. For the first 48 hours, I spent a lot of time wondering if I was making a choice that mattered, and thinking about how I wasn’t habitually looking at Twitter every few minutes to see if I’d missed anything funny, or to see the latest bullshit spewing forth from President Fuckface’s mouthanus. I was, ironically, spending more time thinking about Twitter since I wasn’t using it than I spent thinking about it when I was.

It started out as a 24 hour break, then it was a 48 hour break, then it was the weekend, and here we are one week later and I don’t feel like I’m missing anything important. I feel like I’ve given myself more time to be quiet and alone, more time to reflect on things, and I’ve created space in my life to let my mind wander and get creative.

I’m not creating as much as I want to, and I’m starting to feel like maybe I’ll never be able to create as much as I want to, but I’ve gotten some stuff done this week that probably wouldn’t have gotten done if Twitter had been filling up the space that I needed.

Here’s a little bit from my blog post that became a short story that grew into a novella that is now a novel, All We Ever Wanted Was Everything:

My mother was leaning against her car, talking with one of the other moms, when we arrived. My sister was throwing a Strawberry Shortcake doll into the air and catching it while they watched. I walked out of the bus and across the blazing hot blacktop to meet her.

Willow, catch!” My sister cried, sending Strawberry Shortcake in a low arc toward me. I caught her without enthusiasm and handed her back. “You’re supposed to throw her to me!” Amanda said, demonstrating. Her doll floated in a lazy circle, arms and legs pinwheeling, before falling back down into my sister’s waiting arms. The writer in me wants to make a clever reference to how I was feeling at that moment, about how I could relate to Strawberry Fucking Shortcake, spinning out of control in the air above us, but it feels hacky, so I’ll just talk about how I wanted to make the reference without actually making the reference, thereby giving myself permission to do a hacky writer’s trick without actually doing it. See, there’s nothing tricky about writing, it’s just a little trick!

It’s still in the first draft, and I may not keep all or even any of it, but after putting it aside for months while I was depressed about too many things to look at it, it feels so good to be back into this story.

Oh, speaking of writing, I got notes back from the editors on my Star Wars 40th anthology submission. I thought that, for sure, they’d want me to rework a ton of it, but all they asked me to do is change a name! And they told me it was beautiful! So I’ve been feeling like a Capital-W Writer for a few days.

And speaking of feeling happy for a change, Hasbro and Machinima announced that I’m a voice in the next installment of the Transformers animated series, Titans Return. And it feels silly to care about this particular thing, but Daily Variety put my name in the headline, which made me feel really, really good.I’ve always felt like the only thing that should matter is the work, and that the work should be able to stand on its own … but that’s not the reality even a little bit. Daily Variety is the industry’s paper of record, so when it chooses to put you in the headline of a story, people pay attention and it matters in the way that can make the difference between getting called for a meeting, or the last ten years of my life as an actor.

It’s also a good reminder that, even if I’m not getting the opportunities I want to be an on-camera actor, it is entirely within my power to create the space I need to be a writer.

 

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The divisiveness plaguing American politics today is nothing new, says constitutional law scholar Noah Feldman. In fact, it dates back to the early days of the republic, when a dispute between Alexander Hamilton and James Madison led the two Founding Fathers to cut ties and form the country's first political parties. Join Feldman for some fascinating history of American factionalism -- and a hopeful reminder about how the Constitution has proven itself to be greater than partisanship.
[syndicated profile] badastronomy_feed

Posted by Phil Plait

Just over two years ago, the New Horizons spacecraft provided humanity with its first close-up photos of Pluto in history.

These images changed the way we see the icy world forever. What we learned was staggering. It has vast, smooth regions on its surface indicating they’re geologically young; mountains as tall as the Rockies but made entirely of water ice; strong implications of liquid water under its surface despite the bone-shattering cold temperatures on the surface.

The close encounter lasted only a few hours, because you have a choice: Get to Pluto in less than a lifetime, or spend more time there. Pluto is so far away that even New Horizons, barreling across the solar system at 14 kilometers every second, still took nearly a decade to get there. It was traveling so rapidly that the visit was short.

 

But, despite the rapid flyby, there’s an advantage to moving faster than a speeding bullet: There are other targets out there in the inky depths of the outer solar system, and if you plan things right, you might just get to see them, too.

Even before the Pluto encounter, astronomers started trolling that region of space to look for another suitable target. They found one: 2014 MU69, an icy chunk of debris likely at most 20-40 kilometers across. It orbits far, far past Neptune, 6.5 billion kilometers from the Sun. It’s part of the Kuiper Belt, a ragtag collection of material left over from the formation of the solar system itself. If you don’t count Pluto (and I do), the first Kuiper Belt Object seen was only in 1992, and we now know of thousands.

But they’re so far away and so small that it’s hard to know what they’re like in detail. And that’s why MU69 is so important. New Horizons will show it to us up close for the first time.

The plan is for the spacecraft to fly within 10,000 km of MU69 on January 1, 2019. Maybe closer. But, to do that, we need to know more about it. How big is it? What shape is it? Is there anything else around it that could interfere with the flyby, like moons, rings, or debris?

These things are difficult to determine, but astronomers got a big clue this week due to geometry. In this case, the stars literally aligned.

Well, the Earth, MU69, and a star aligned. On July 17, 2017, from certain points on Earth, MU69 appeared to pass directly in front of a faint star. Astronomers call this kind of event an occultation, and when it happens, the star’s light is blocked, and it seems to momentarily disappear! In a sense, in this case, we’re in the shadow of MU69.

The occultation provides critical information: Because we know how fast MU69 is moving across the sky, the length of time the star blinks out tells us the width of MU69.

But there’s more. If you observe the occultation from different locations, you see different parts of MU69 passing in front of the star. If it’s a perfect sphere, then some locations will see a shorter occultation because the star cuts a chord behind it, not the full diameter. In fact, the shape itself can be determined by how long the occultation lasts at different positions on Earth.

map of occultation

Map showing the path of the shadow of 2014 MU69 across the Earth. Credit: SwRI

So New Horizons scientists dispatched telescopes to South America, where the shadow of MU69 was determined to fall across the Earth. In all, a couple of dozen small (40 cm) ‘scopes were deployed, equipped with cameras to record the event.

And … they caught it! At least five telescopes saw the star blink out. That, too, is very useful: If a ‘scope didn’t see it, then that provides an upper limit to the size of MU69 as well. The entire occultation lasted less than two seconds, too, so timing and location were everything here.

animation of occultation

Animation of the star blinking out as MU69 passed in front of it. This is actual data from the event; the time between frames is 0.2 seconds. Credit: NASA / JHUAPL / SwRI / Emily Lakdawalla

 

The data are still being processed, and we should have some numbers soon. I’ll note that there were two predicted occultations of two different stars before July 17, but nothing was seen. That means MU69 is probably smaller than previously thought, which, in turn, means it might be more reflective — if we know the distance and how bright it is, then its size depends on how shiny it is. A darker object would have to be bigger to look brighter, so even this non-detection tells us more about it.

My friend and super-solar-system-science communicator Emily Lakdawalla has more about the efforts to record this event. She also wrote a nice piece on what we knew about MU69 from a couple of years back, too.

I can’t stress enough just how difficult this sort of event is to plan! MU69 was only discovered in 2014 using Hubble images. It has a visual magnitude of 27 — that means the faintest star you can see with your unaided eye is 250 million times brighter! Then, using those images, the team had to calculate an orbit for it, and do so with such precision that they could extrapolate where it would be over the next year or two and see if it would pass in front of any stars. Then they had to plan the logistics of all that travel, coordinating the mission and making sure the data were recorded. Yet, as difficult as all that was, they were able to do it so well and with such accurate timing that several of the telescopes did in fact see the star blink out.

Mind you, MU69 is far, far too faint to even see with the telescopes used. So the astronomers had to keep taking data and hope.

And it paid off. Now, armed with more data, they’ll be able to plan the upcoming encounter with a little more confidence. As for what we’ll actually see when New Horizons gets to MU69, well, no one really knows.

If we did, it wouldn’t be exploration now, would it? But in less than 17 months, we’ll find out.

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I am like….90% sure I’m going camping this Friday. 

It depends a bit on the weather, but I’m mostly packed, I’ve cooked food that’s currently waiting in the freezer, and I have acquired the third Diane Mott Davidson book to read. 

The plan is to leave work early, catch the train to the campground, camp overnight, and in the morning hike out to a different train station further down the line, about a seven-mile trek, to do a longer endurance test than last weekend’s. Then I’ll catch the train home around noon on Saturday.

If something goes wrong, I can catch an evening train home on Friday until eight o’clock, or starting in the morning at 5:30, with little to no exertion. It’s pretty low-risk and I’m well stocked. I don’t have a sleeping pad, but my backpack has a partial one built-in, and I have one arriving tomorrow (though it might be too bulky, we’ll see). And honestly in this heat, I might just sleep on top of my sleeping bag in any case. 

Worst case scenario, the campground has heated, lockable shower cubicles with nice big floors. I’ve slept on worse. 

Caaaaaaamping! *jazz hands*

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Why do so many companies make bad decisions, even with access to unprecedented amounts of data? With stories from Nokia to Netflix to the oracles of ancient Greece, Tricia Wang demystifies big data and identifies its pitfalls, suggesting that we focus instead on "thick data" -- precious, unquantifiable insights from actual people -- to make the right business decisions and thrive in the unknown.
[syndicated profile] badastronomy_feed

Posted by Phil Plait

The European Space Agency’s current ExoMars mission has had a bumpy ride from the third to the fourth planet from the Sun, but right now things are looking good.

Launched in 2016, the mission had two parts: The Trace Gas Orbiter (or TGO), which was designed to orbit Mars and investigate the planet’s atmosphere, and the Schiaparelli lander, which was mostly a technology testbed to better understand how to land robotic explorers on Mars. NASA has done the latter many times — not always successfully —  but ESA hasn’t done so yet.

TGO is doing fine. It was initially on a long, elliptical orbit around Mars (the easiest kind to establish upon arrival) but has been executing a series of short engine burns that drop the low point in its orbit (called periareion, for “near to Mars”) into the upper parts of the atmosphere. That causes drag with the thinly distributed molecules there, taking energy away from the spacecraft’s orbit, lowering and circularizing it. Called aerobraking, this maneuver will eventually put TGO into a circular orbit at a height of about 400 km above the surface. The spacecraft will then orbit the planet once every two hours or so.

That will happen in 2018. Right now, it’s still in the elliptical orbit that stretches from about 200 km above the surface to 33,000 km out. That’s still a useful path! For example, it passed about 7700 km from the Martian moon Phobos, and dusty, battered space potato of a satellite, and took this pretty nifty image in October of 2016:

Phobos

Phobos, one of the two small moons of Mars. It’s about 27 km across through its long axis. Credit: ESA/Roscosmos/CaSSIS

It also has been observing the thin air of Mars, detecting carbon dioxide (the major component) as well as small amounts of water vapor. Eventually it will look for traces of methane, which has been positively detected in the Martian atmosphere but is poorly understood. On Earth, the major source of methane is biological activity, including livestock (by, um, outgassing) and human activity, including production and use of coal. It’s a greenhouse gas, but methane molecules are fragile and tend to react easily when oxygen is present. In Earth’s air the amount of methane is more or less stable, with the destruction of the molecules balancing their creation. That’s good, because methane is a very strong greenhouse gas, stronger than CO2.

Its presence on Mars is more difficult to explain. It’s due to some sort of geological process, but just what isn’t well known. TGO will map its concentration and location, hopefully providing needed clues to the gas’s origin.

Mellish crater

TGO mosaic of part of Mellish Crater, a 100 km wide crater near the Martian south pole. It was assembled from 40 images taken on March 5, 2017. Credit: ESA/Roscosmos/CaSSIS

Things, however, are not so good for the Schiaparelli lander. In fact, that part of the mission, in some sense, ended before it really began: It crashed into the planet on October 19, 2016, instead of softly touching down.

The crash investigation recently ended, and they found that a confused measurement device on board Schiaparelli instigated the impact. The lander deployed from the orbiter cleanly on the way to Mars. As the lander entered the upper atmosphere, the parachute also deployed as designed. However, it caused the lander to vibrate, or oscillate, for a few moments. A device called an inertial measurement unit confused that motion for a rotation of the spacecraft and got a reading far higher than it was designed for. It saturated, basically pegging the needle.

This only lasted for about a second, but that was enough. The odd reading was interpreted by the lander as its being upside-down, and the software wasn’t designed to handle that. When it did the math, it incorrectly calculated that it had a negative altitude, and so it interpreted this as being on the surface. It ejected the parachute and fired its landing thruster, but it was far too early and for too short a time.

This happened while it was still 3.7 kilometers (over two miles) above the surface. It free-fell the rest of the way, impacting Mars at a speed of 370 km/hour — nearly four times faster than a car on the highway. It didn’t survive. The impact scar and debris have been spotted by other orbiters.

Schiaparelli crash site

The Schiaparelli crash site, imaged by the Mars Reconnaissance Orbiter in November 2016. The surface disturbance is obvious, and the brighter dots around it may be debris from the spacecraft. The image is about 234 meters on a side. Credit: NASA / JPL / UA / Emily Lakdawalla

The good news is that the engineers learned a lot from the event, and won’t make those same mistakes a second time. In fact, they’ve said that some of the errors leading to the crash wouldn’t have been detected if the lander had made it down safely, and that could have led to disaster on a future mission. Since Schiaparelli was designed to test the hard- and software, in one way, this was fortunate. Better Schiaparelli than a far more sophisticated and expensive science lander.

Not that this crash was a good thing, but when it comes to space travel, every mistake is a chance to learn. At least, in this case, the loss was minimized.

Mars and the Sun
In mid-July 2017 Mars and the Sun are very close together in the sky. Credit: Sky Safari

Right now, Mars is nearly on the opposite side of the Sun as seen from Earth. Our orbit is closer to the Sun, and faster. Once every 26 months or so, we pass between the Sun and Mars, and then, roughly 13 months later, the Earth is on the opposite side of its orbit from Mars (remember, Mars moves, too, so it takes a while for us to pull ahead); this means that, from Earth, Mars and the Sun are very close together in the sky (called solar conjunction). That means it’s more difficult to communicate with spacecraft there — the Sun is the brightest radio source in the sky — so TGO has been commanded to sit tight in its current orbit for now. In a few weeks, it’ll start dipping its orbit again, hopefully on its way to a nice, stable circular science orbit.

It joins a veritable fleet of other robotic craft there, including some from the U.S., one from India and another by the ESA. It may be quite some time before humans go to the Red Planet, but our uncrewed proxies are still working apace. Mars is dry and cold and probably lifeless, but that doesn’t mean it’s not a dynamic and interesting world. I’m glad humans all over our planet are still interested in exploring it.

[Top image: ESA/ATG medialab]

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Next step? Pet falcon.

Jul. 18th, 2017 08:01 pm
[syndicated profile] thebloggess_feed

Posted by thebloggess

Okay.  Last week I told you that we have lawn gerbils and then a few days later it turned out we maybe had fairies but there have been more developments and those developments are that squirrels are assholes and I … Continue reading
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Right now, billions of neurons in your brain are working together to generate a conscious experience -- and not just any conscious experience, your experience of the world around you and of yourself within it. How does this happen? According to neuroscientist Anil Seth, we're all hallucinating all the time; when we agree about our hallucinations, we call it "reality." Join Seth for a delightfully disorienting talk that may leave you questioning the very nature of your existence.
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Posted by Phil Plait

Today, some bittersweet spacecraft news: The LISA Pathfinder mission is shutting down. That’s always a bit sad, but in this case, in sum, it’s actually good news: That’s because it accomplished all its goals. And even better, it means that a bigger, beefier mission will take its place! That mission, called LISA, was recently approved by the European Space Agency to continue its planning phase, aiming for a launch in 2034.

Why am I happy about this? Because LISA is the Laser Interferometer Space Antenna, and it will use what is essentially Star Trek technology to detect merging black holes all across the Universe.

So, yeah. How awesome is that? And, for a while, I feared it would never get off the ground. It hasn’t yet, but the odds are looking much better now.

OK, you probably want a modicum of background here. I’ll be glad to help.

Maybe you’ve read reports about LIGO, the Laser Interferometer Gravitational-Wave Observatory, which recently detected black holes merging for the third time. I wrote about that event and gave a lot of background a couple of years ago when LIGO bagged its first black hole coalescence.

In a nutshell, one of the predictions of Einstein’s Theory of Relativity is that when matter is accelerated it creates ripples in the fabric of spacetime, much as shaking a bedsheet up and down causes ripples in the fabric. These ripples are stronger if the objects are very massive, very dense and accelerated very rapidly.

You don’t get more massive, more dense and more accelerated things in this Universe than two black holes at the very moment they eat each other.

 

There are a few ways this can happen. Probably the most common is from black holes that form when massive stars explode. If those stars are orbiting each other in a binary system, then, eventually, after both stars blow up, you get two black holes orbiting each other. As they emit gravitational waves — those Einsteinian spacetime ripples — they spiral in toward one another. Over a long time (usually billions of years), as the distance between them closes, they orbit faster and faster. Then, finally, accelerating each other to very nearly the speed of light, they merge into a single bigger black hole, emitting a fierce, sharp blast of gravitational waves.

These ripples in spacetime then move across the Universe at the speed of light. When they wash over our planet, they physically compress and expand space itself. The effect is incredibly tiny by the time these waves reach us: A typical ruler would only shrink or expand by a tiny fraction of the size of a proton! But these effects can be measured because we are very clever apes, we humans.

LIGO was built to find these ripples, and after decades of trying, it works! It can now feel the Universe shake as black holes collide.

Merging black holes art

 

But LIGO, as amazing as it is, isn’t nearly as sensitive as what’s possible. Enter LISA.

LISA is similar to LIGO, but it’ll be in space. There are lots of advantages to this. For example, LIGO is so sensitive it has to worry about individual oxygen atoms hitting its mirrors, distorting the signal. In space there’s no air, so that’s an improvement.

Also, this stretching of spacetime is easier to measure if you have a longer baseline. If your detector is short it only stretches and contracts a little bit, but if it’s 10 times longer the effect is 10 times bigger. LIGO has mirrors spaced a few kilometers apart, making it highly sensitive. Because LISA is in space, its detectors can be much farther apart. In fact, the plan right now is for the components to be separated by about 2.5 million kilometers!

If you want to think of it as sound (which it isn’t, but the analogy isn’t bad), LIGO can hear the loudest black hole mergers. LISA will hear the whispers. In fact, it should also be able to detect mergers between neutron stars and even white dwarfs, which are far “quieter” than their denser black hole brethren.

So, how does it work? LISA is actually three disc-shaped spacecraft, launched together on one rocket. They each have an onboard propulsion system that will move them to their final separation of several million kilometers, forming an equilateral triangle in roughly the same orbit as Earth, but 20 or so million kilometers away from us.

Like LIGO, LISA will use lasers. Each spacecraft will have onboard two lasers, each of which will fire at one of the other two spacecraft. Using a technique called interferometry, the distances between the spacecraft can be measured with utter precision:

 

But there’s a problem with this. The spacecraft need to be able to measure their relative positions with incredible accuracy, so that the teeny tiny effects of a passing gravitational wave can be measured. But there are lots of forces in space that would totally wash that out. Tides from the Earth, Moon, and Sun, cosmic rays, solar wind and more would all be far stronger, moving the spacecraft around and ruining the measurements.

To overcome this, inside each laser assembly is a small, exquisitely crafted cube made of gold and platinum (yes, seriously; they’re very stable and that makes them useful). Each cube, called a test mass, is about 4.5 or so centimeters on a side and has a mass of about 2 kilograms. They are totally disconnected from the LISA spacecraft, untouched by it in any way, allowed to float completely freely. The tolerance is extreme: No force on the cube is allowed more than about that exerted by the weight of a bacterium.

See what I mean by Star Trek technology?

LISA spacecraft

Artwork showing one of three LISA spacecraft “connected” to the other two (one above and to the left, the other off screen to the left; both 2.5 million km away) via lasers. Credit: AEI/Milde Marketing/Exoze

 

In this way, the cubes are freely floating in orbits around the Sun, and the spacecraft keep position around them. Using extremely sensitive sensors, each spacecraft keeps itself precisely aligned with the cube inside it, measuring their exact location at all times. 

The cubes act as benchmarks for the spacecraft around them. As long as the cubes are allowed to move freely, then a gravitational wave passing through them would change their relative separation, allowing it to be detected. The spacecraft act like shields, preventing outside forces from affecting them … really, these forces affect the spacecraft, which then use incredibly low-thrust engines to maintain their strictly controlled positions. If there’s a force on the spacecraft, say the solar wind, then the thrusters counteract that to make sure the spacecraft stays perfectly centered around the cubes. And I do mean weak: It would take a thousand of these thrusters to generate the same weight as a piece of paper in your hand!

LISA test mass

The LISA Pathfinder test mass, very similar to the ones that will be used on LISA. It's a cube of gold and platnium with a mass of about two kilos. Credit: RUAG Space, Switzerland

 

I like to think of all this using an odd analogy: curling. That’s a sport played on an ice lane where a player throws a heavy mass (called a stone) and tries to place it in a target area downrange. Other players, called sweepers, have brooms and they rapidly sweep the ice ahead of the stone, decreasing the friction and making sure the stone’s trajectory is true.

For LISA, the test masses are the stone, and the sweepers are the spacecraft. They never touch the stone, but they make sure its path is true.

Now, if a gravitational wave passes through the LISA spacecraft, the pattern of light created by the laser changes, and this can be measured with ridiculous accuracy. Even though they will be separated from each other by a distance several times greater than the distance of the Moon from Earth, they will measure their relative positions to an accuracy of a few trillionths of a meter. Yes, trillionths. For those who love words as much as I do, a trillionth of a meter is a picometer. Feel free to work that into your next conversation.

And, again, this exemplifies the idea of how astonishingly advanced this tech is.

This brings us back to LISA Pathfinder. We know all this technology needed for LISA will work because the European Space Agency successfully tested it using Pathfinder. It launched in late 2015 and was equipped with lasers, cubes and other bits of tech LISA will utilize to measure the whisper from colliding hyperdense cosmic objects. It was amazingly successful and completed its mission on June 30. Today it will be shut down, having paved the way for LISA to continue.

I’m glad this is happening. Many years ago, NASA was partnered with the European Space Agency to help build LISA. I actually worked a bit on the Education and Public Outreach for the mission, writing up descriptions of how it worked and what it would do. But shortsighted budgetary decisions meant NASA had to pull out of the development, which upset me greatly at the time.

However, over time and with a lot of cajoling by scientists, the U.S. has rejoined the mission as a senior partner, with the ESA leading the way. I’m very glad to see this. Now that LIGO has shown we can detect gravitational waves, and LISA Pathfinder has shown the advanced technology is possible, LISA itself will open the floodgates of data. It took a huge effort for LIGO to allow us to dip our toes in the water. Hopefully LISA will let us dive in.

My thanks to NASA LISA Study Scientist Dr. Ira Thorpe for talking to me about how the spacecraft measure their distances and clearing up a misconception I had about the test masses!

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johnny sokko and his flying robot

Jul. 17th, 2017 11:22 pm
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Posted by Wil

A young boy aids in the fight against a mechanized terrorist organization as the sole controller of a prototype giant robot.

I couldn’t sleep, so I wandered into the weird and comforting landscape of UHF television’s modern equivalent, which in this case is a digital antenna station on 56.4 here in Los Angeles, called Comet TV*

For the next half hour, I watched this magnificently bizarre thing called Johnny Sokko and His Flying Robot. As far as I can tell, there’s this little kid called Johnny Sokko, and like all the other kids in school were all “Johnny Sokko, you’re a stupid face!” so he was like “h*ck you guys, I’m going to get a giant robot and live on a boat for some reason. Oh, and also, I’m like 8 or whatever, and I’m in charge of a giant flying murder machine. So watch your step, bitches.” Johnny gets this this giant robot who flies, and he controls him by issuing commands into a gold wristwatch. Instead of telling the robot to breakdance for his endless amusement, Johnny cries a lot and makes the robot save the world from a squid guy or something who lives in a sunken spaceship, adjacent to a pineapple under the sea? It’s all a little fuzzy in the translation, I’ll be honest, but I think I got the gist of it.

Anyway, I probably made some of that up, but this is all true: There’s a Flying Robot who is vaguely Egyptian. There’s a Gargoyle Gang, the Emperor Guillotine, a military group of children who are called Team Unicorn and are the only thing between Earth’s survival and intergalactic destruction for some reason, and all the bizarre 1960s Kaiju visual effects you could ever hope for. The music is exactly what you want it to be, and at one point, an entire freeway overpass is destroyed, because who among us hasn’t wanted to do that!

A quick search on a few of the Internets made it clear to me that I was not just way late to the party on this (the short I saw was originally released in Japan in 1967, as Giant Robo because obviously) but I am also discovering this literally decades after it became popular with the cool kids. So if you’re like OH GREAT WIL WHEATON THANKS FOR WASTING MY TIME WITH SOMETHING I ALREADY KNEW ABOUT now you can feel like a jerk because it’s new to me, Roland. It’s new to me!

It’s weird, and fun, and overflowing with potential audio samples, so I thought I would share it with you today. Here’s what I think is the first episode, in which we meet Johnny Sokko, the Flying Robot, an unsettling sea monster, and more:

There are several collections of Johnny Sokko films at the Internet Archive. I guess you can also buy remastered DVDs if you want to go that route (though I strongly believe that the faded and aged look of the originals at archive.org is a significant contributor to the charm of the thing.)

Good luck. We’re all counting on you.

*It’s owned by the profoundly evil Sinclair Broadcasting Group, which is a giant bummer. You can buy evil offsets by supporting ACLU and SPLC, if it makes you feel better.

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Posted by fgemods

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Nominations are now open for the Fandom Growth Exchange! The Fandom Growth Exchange is a multi-fandom exchange for fandoms, relationships, and characters that have ten or fewer complete fics (or five or fewer contributing authors) on AO3. Check out the tagset!

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Martin Landau: 1928–2017

Jul. 17th, 2017 04:41 pm
[syndicated profile] badastronomy_feed

Posted by Phil Plait

Well, damnation. Martin Landau has died.

You might know him for his iconic portrayal of Bela Lugosi in the movie Ed Wood —and you should; it earned him an Oscar, deservedly.

But to me he has been and always will be Commander John Koenig, the hot-headed commander of Moonbase Alpha, leader of the 311 men and women there, making the big decisions after the Moon was accidentally blasted out of Earth orbit on September 13, 1999.

Sound silly? Well, yeah, it is. But it was the plot for the TV show Space:1999, and let me tell you, I loved it when I was a kid. Even after all these years (it aired in the US in the late '70s) I still have a deep fondness for it. To this day it has one of the best and coolest spaceships ever, the Eagle Transporter.

I was a tween/young teen at the time the show aired, and my friend John and I never missed an episode. I liked Star Trek at the time (not as much as I do now, though), and Kirk was something of a male role model for me, as was Spock for my science side. But it was Barry Morse as Professor Victor Bergman who was really my fictional science inspiration, and Landau's Koenig I looked up to.

Looking back at it now, with adult eyes and experience, my opinion of the character is different. I understand now that Koenig's character was somewhat erratically written, with anger guiding his decisions as often as concern over the safety of the base or the desire to explore. Of course, we all of us have conflicting motivations sometimes, don't we?

But when I was a kid, I saw him simply as the hero. Oh, how I loved Koenig's take-charge attitude when things got rough, how fiercely he defended his friends and comrades, how quick he was to boil over when they were threatened! I thought he was the epitome of derring-do.

Times were different then, and I am not the person I was when I was 13. Thank heavens! But still, some of that boy is me, parts of him at least. The love of science and science fiction, of story telling in the depths of the Universe … that lives on in me, as does whatever part of that was guided by Koenig and the rest of the Alphans.

You can read about Landau's other achievements and other roles elsewhere. But for me, every year on September 13thI’ll tip my hat toward the Moon. I'll always wish Moonbase Alpha godspeed, and I'll always remember Martin Landau for a role on a show that shaped my love for space forever.

[Hero image credit: Gerry Anderson Productions]

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Climate change is real, case closed. But there's still a lot we don't understand about it, and the more we know the better chance we have to slow it down. One still-unknown factor: How might clouds play a part? There's a small hope that they could buy us some time to fix things ... or they could make global warming worse. Climate scientist Kate Marvel takes us through the science of clouds and what it might take for Earth to break its own fever.
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Posted by Phil Plait

Our Milky Way galaxy is a collection of gas, dust, dark matter, and a couple of hundred billion stars. Most of those stars orbit the galactic center in a pinwheel-shaped disk about 100,000 light years across and a few thousand light years thick, but there’s also a vast roughly spherical halo of stars around the galaxy stretching out about 100,000 light years, itself.

Most of the stars in the halo are moving around the Milky Way in nice, normal orbits. However, over time a handful have been discovered that are weird: They’re moving too fast.

Milky Way map

A map of the Milky Way based on real observations. Not shown is the huge spheroidal halo of stars and hot gas surrounding the disk of our galaxy. Credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

 

These stellar bullets are screaming around space much faster than the stars around them. Sometimes their velocity is so high that the galaxy’s gravity can’t hold on to them: Their destiny is to escape the galaxy forever.

We call these high-velocity stars. A really big question is actually a pretty a simple one: Where did they come from? There are lots of possible origins for these stars (which I’ll get to in a sec), but a new one has just been found, and I’ll be honest, it surprised me: They are coming from the Large Magellanic Cloud (or LMC), a satellite galaxy of the Milky Way.

That startled me for a lot of reasons, but the biggest is that the LMC is over 150,000 light-years from us, and that’s a long way to travel for a star even at high speed. But a paper just published outlines how it works, and it’s pretty convincing.

The main piece of evidence is that a lot of these high-velocity stars are seen in the constellations of Leo and Sextans. That’s significant, because if you map out the location and orbit of the LMC around the Milky Way, the LMC is headed in that direction (think of it as watching a car zoom past you on a road, and you can see it’s headed toward the east; it might be in front of you at this exact second, but you can extrapolate where it will be in a few minutes). It orbits our galaxy at about 380 kilometers per second, which is really fast, and if you could eject stars from it they would preferentially be found moving in the direction of the LMC itself.

That’s pretty good circumstantial evidence but, to be honest, it’s not enough. Can stars like this, in fact, be ejected from the LMC?

This animation from the journal paper shows nearly two billion years of time as the LMC moves across our sky and the stars ejected from it. The curved path is due to the way the map is shown (like how maps of the Earth can distort the poles); the diustance is listed in kiloparsecs (1 kpc = 3260 light years) and time in millions of years ago. Credit: Boubert et al

 

There are many ways to get stars blowing through space at high speeds. One is if the star starts out in life as part of a binary star, two stars orbiting one another. If they pass really near a black hole, one star can get swallowed by it while the other gets ejected at a pretty substantial clip. We think this happens in our Milky Way when a binary encounters the gigantic black hole at the galaxy’s exact center. Some high-velocity stars seen are consistent with this, but that doesn’t explain the excess seen toward Sextans and Leo. Plus, there’s no evidence the LMC has a big black hole like ours, so that doesn’t really cover the observations.

There are other ways (for example, encounters with other stars in a dense stellar cluster can kick stars pretty hard), but it’s hard to account for both the number and distribution of these stars seen.

contact binary

Artwork depicting a contact binary: two stars orbiting so close together they share a single atmosphere. Credit: ESO/L. Calçada

 

One way seems to fit the bill, though. You start with a binary system, where at least one of the stars is high-mass, more than 8 times the mass of the Sun. Eventually, that star will turn into a red giant, swelling hugely in size. The other star can then draw material off the giant, increasing its own mass. If they are close enough together, they can actually become what’s called a contact binary, a peanut-shaped object which is essentially two stars sharing the same atmosphere! When this happens, the two stars actually can spiral in, getting very close together. As that happens, their orbital speed around each other increases.

Then, catastrophe: The more massive star explodes in a spectacular supernova! If it loses enough mass in the explosion, it no longer has enough gravity to hold the binary together, and the companion star gets flung away at high speed. A-ha! A high-velocity star.

This seems a little unlikely, though. How often does this happen?

Turns out, a lot! The scientists doing the study decided to find out just how common an occurrence this is in the LMC, so they did two things: They used a physical model of how stars form and evolve in the LMC to see how many high-velocity stars you can get this way, and then used a second physical model of the LMC and Milky Way system to see if the gravity of the two galaxies changes the way the stars behave (for example, the gravity of the LMC may slow down the stars ... but the ones shot out ahead of the LMC in its orbit get the galaxy’s velocity added to them, as a ball thrown out a car window gets the car’s speed added to its own).

Runaway star

Artist’s illustration of a runaway star ejected from the LMC (background, using an actual image of the satellite galaxy). Credit: ESO

 

Their model simulated nearly 2 billion years of time, and what they found was pretty cool: Over that time, more than 860,000 stars will have escaped the LMC, making up about 80% of the high-velocity stars seen in the Milky Way’s halo! That shows that it’s extremely plausible that the stars actually seen come from our companion galaxy.

There were other interesting tidbits to come out of this as well. Because these stars were once part of a contact binary, they may have started off lower mass, but gained mass before getting flung out into the Universe. If they wound up with more than about 8 times the Sun’s mass, they, too, would explode over time. The model predicts that about half the stars ejected from the LMC exploded on their way here. These supernovae leave behind either a dense neutron star or a black hole, which means thousands of these objects — tiny, but possessed of super-strong gravity — are blazing past our galaxy even now.

Now, don’t fret: They’re too far away to hurt us in any realistic way, but I do hope some science fiction author hears about this and devises a fun story based on them.

Interestingly, a lot of high-velocity stars are high-mass blue stars (called B stars in the astronomical stellar classification system). That, too, is naturally explained by them once being in a contact binary, where they gained enough mass to fall into this category.

So, how do we prove this? High-velocity stars can be found in a number of ways. In general, it’s through their spectrum; when you break the light up from a star into thousands of narrowly sliced colors, you can learn a lot about them, including their speed. But that’s a hard measurement to make on a large scale.

You can also take images of lots of stars in the sky, wait a few years, then do it again. Stars moving rapidly enough in space will move noticeably in such a survey (if the observations are accurate enough). And there is such a survey: Gaia, which is mapping a billion stars in the Milky Way. Over the course of its multi-year mission it may find quite a few of these runaway stars.

So, is this idea of cannonball stars from the Large Magellanic Cloud correct? Maybe. I do like it, and it explains a lot. The good news is it’s testable, making predictions about the numbers, locations and types of stars we should expect to see in the Gaia survey. Time will tell, and we won’t have to wait too long, since the survey results needed for this will be released over the next few years.

Every time I think I’ve heard everything about astronomy, something new comes along. Alien invader stars from another galaxy! Science is just so much fun.

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