Bad Astronomy
The entire universe in blog form

Feb. 12 2016 9:15 AM

OK Go Defies Gravity

OK Go is a band that’s a bit hard to define; Wikipedia lists them as “American alternative rock,” which is possibly the least specific adjectival phrase I can think of (besides maybe “mostly carbon-based”).

They make ridiculously catchy songs and are better known for their quirky and astonishing videos. Maybe you saw the one they did for “Here It Goes Again” where they do synchronized treadmill calisthenics. Or maybe “The Writing’s on the Wall,” which I featured on the blog, because of my love of optical illusions.


Well, rejoice! They’ve just released a new video, and they have honestly outdone themselves. This is truly amazing, so I’ll just let you watch it first before I talk about it! Behold, “Upside Down and Inside Out”:

OK Go - Upside Down & Inside Out

Hello, Dear Ones. Please enjoy our new video for "Upside Down & Inside Out". A million thanks to S7 Airlines. #GravitysJustAHabit

Posted by OK Go on Thursday, February 11, 2016

Ha! See? I told you. Delightful.

So what did you just see?

As the video claims, they didn’t use wires or green screen for this. What they used was … SCIENCE!

Or in this case specifically, PHYSICS. They filmed this video on an airplane capable of making steep arcs up and down in the air, over and over again. Near the top of the arc, the only forces acting on the plane are gravity and air resistance. The engines are cut back and the plane pitched to an angle that exactly compensates for air resistance, leaving only gravity acting on the plane.

zero g ballistic flight
How to take a load off.


The plane then follows a ballistic trajectory, governed only by Earth’s gravity. The plane continues up, tops out, and then starts to fall. A few seconds after that the engines are throttled up, the plane pulls out of the dive, levels off, and it’s ready to start again.

During those brief seconds around the top of the arc, the plane and all the objects inside it are freely accelerated* by gravity at the same rate, so to anyone inside, they feel weightless! If you hold up a ball in front of you and let go, it’ll appear to float there. Really you’re just all traveling along the same ballistic trajectory, but your body will feel like it’s freely falling. 

And that’s the trick to this video! They built a mock airplane cabin inside of a Russian Ilyushin-76 airplane (flown by the Russian S7 airlines), and filmed it as the plane made a series of arcs. So when you see them floating around weightless, well, that’s no trick. Except a trick of … SCIENCE.

But there’s so much more going on than just that!

For example, the weightless periods in this particular flight lasted about 27 seconds. That’s about the most you can do in this case. And the price you pay to be weightless at the top of the arc is to pull out at nearly twice the force of gravity. That happens pretty suddenly, going from 0 to 2 G's rapidly. Everything falls to the floor of the cabin, and if you’re not ready for it, you will too.

So how did they record a video that’s much longer than 27 seconds? I asked exactly this of Damian Kulash, the lead singer and guitarist for OK Go, and he told me what they did. It’s quite clever.

First, they created each “scene” that they could do in the weightless time allotted. Given the tempo of the song, each scene is 21 seconds long. They then performed the routine slightly slower (at 21/27 = 78 percent of the actual speed), then sped it up in post-processing! This also eliminates another issue: In zero-G, it just looks like everything has been slowed down, like it’s been faked. Speeding up the footage gets rid of that problem.

Mind you, this entire video was done in one continuous shot! They didn’t cut and redo any scenes; it was filmed in one take in the order you see it. At the end of each scene they braced for the feeling of gravity to come back, waited it out, then started the next scene once everyone was weightless again. After they were done, they edited out the parts with them standing there, then used a morph to smooth over the transitions. Those jumps are hard to notice, actually. See if you can spot them! Hint: There are six of them.


scene from the video
Seriously my car was that exact shade of teal/aquamarine.


Some of the choreography (most notably with the “stewardesses”; I loved that retro bit, especially since I once had a car the exact color of their uniforms) looked like it could only have been dreamed up in weightlessness, so I also asked him how the heck they planned this.

It turns out they did it in several steps. They planned as much as they could, then booked a week of test flights (six flights in total) in Russia to try things out. They came back home, worked out the details, then went back to Russia for a week of six more flights to rehearse, then a week of eight flights to record it.

Easy, right? Yeah, not so much. Besides the amazingly detailed choreography, they had to deal with … well human digestive issues. There’s a reason NASA calls its zero-g astronaut training aircraft the Vomit Comet. I asked Kulash about this, and he told me, “… yes, lots of puking.” But apparently that was only at the beginning, and after a while they all got used to it (with the help of some anti-nausea medication).

They are made of sterner stuff than I am. I flew on a fighter jet for my show Bad Universe a few years ago, and while the high acceleration didn’t bug me (in fact I enjoyed it), the transitions are what killed me; going from one G to four in a fraction of second destroyed my middle ear. I was sicker than I ever have been in my life (though I’ll brag I didn’t throw up … but it was a very, very near thing).

But what OK Go did? Geez, I’d throw up every piece of food I ever ate in my entire life. Kudos to them.

I also loved the scene with the balloons at the end. They spent a lot of time in stores looking at products that might behave in funny and odd ways in weightlessness, and popping balloons filled with liquid was a stroke of genius. The patterns the liquid makes once the balloons are popped are like lessons in hydrodynamics. It’s beautiful.

Like the illusion-based “The Writing’s On the Wall” video, “Upside Down and Inside Out” is like a lesson in perception, as well as one in physics. I can see high school science teachers using this video to get their students to think differently about motion, forces, and even on how to plan something on this scale; creating experiments in physics is much like planning a video like this.

You might say … they fall along the same trajectory.

My congratulations to the band and their crew, and my thanks to Kulash for contacting me about it. Getting an email from an artist you admire, much like lowering the effect of gravity, is a really great way to put a bounce in your step.

*In physics, deceleration is just a negative acceleration, so we tend to just call it all “acceleration”; if you’re slowing down, then you’re being negatively accelerated or accelerated in a different direction.

Feb. 11 2016 11:20 AM

LIGO Sees First Ever Gravitational Waves as Two Black Holes Eat Each Other

Better start shining up some new Nobel Prize medals: Scientists have reported that, for the very first time in history, they have detected gravitational waves.

And oh my yes, this is a very big deal. It will open up an entirely new field of astronomy, a new way to observe the Universe. Seriously.


Gravitational waves (not to be confused with gravity waves, which are a totally different thing) are ripples in the fabric of spacetime, caused when a massive object is accelerated. By the time they get here from distant astronomical objects, the waves have incredibly low energy and are phenomenally difficult to detect, which is why it’s taken a century to discover them since they were first predicted by Einstein’s Theory of General Relativity. Essentially every other prediction of GR has been found to be correct, but the existence of gravitational waves has been maddeningly difficult to prove directly.

Until now. And what caused the gravitational waves they detected at the Laser Interferometer Gravitational-Wave Observatory is as amazing and mind-blowing as the waves themselves: They caught the death spiral and aftermath of two huge black holes 1.3 billion light-years from Earth, merging together in a titanic and catastrophically violent event.

Mind you, we’ve had some good evidence such binary black holes existed before this, but this new result pretty much proves they exist and that, over time, they eventually collide and merge. That’s huge.

The black holes had masses of 36 and 29 times the mass of the Sun before they merged. After they merged they created a single black hole with a mass of 62 times that of the Sun. You may notice those masses don’t add up right; there’s 3 solar masses missing. That mass didn’t just disappear! It was converted into energy: the energy of the gravitational waves themselves. And the amount of energy is staggering: This single event released as much energy as the Sun does in 15 trillion years.

I know. There is nothing about this story that isn’t incredibly cool.

The actual data received by the two LIGO facilities. The wiggles in the plot are due to the physical warping of space as gravitational waves emitted by the merging black holes passed through the Earth.

Abbot et al. 2016

So, to understand all this better you’ll need a wee bit of background. This is all very mind-bendy stuff, but I promise it’s worth it.

What Is a Gravitational Wave, Anyway?

One of the outcomes of Einstein’s General Relativity theory is that space and time are two facets of the same thing, which we call spacetime. There are lots of analogies for it, but you can think of it as the fabric of space, a four-dimensional tapestry (three of space and one of time) in which we are all embedded. Remember, it’s not literally like this; we’re using an analogy. But it’ll help you picture it.

We think of gravity as a force, pulling us toward an object. But Einstein revisualized it, seeing it as an outcome of the warping of spacetime. A massive object distorts the shape of space, and another object moving through that warped space gets accelerated. We see that as gravity. In other words, matter tells space how to bend, and space tells matter how to move.

warped space
Objects with mass warp space, which we feel as gravity.


Another outcome of the mathematics of GR is that if a massive object is accelerated, it will cause ripples, waves, to move away from itself as it moves. These are actually ripples in the fabric of spacetime itself! Spacetime expands and contracts in complicated ways as a wave passes, a bit like how ripples will move out from a rock dropped into a pond, distorting the surface of the water.

There are lots of ways to generate gravitational waves. The more massive and dense an object is, and the harder it accelerates, the sharper and more energetic the waves are. The Earth moves around the Sun once per year, accelerated by the Sun’s gravity. But the motion is too slow and the Earth’s mass too low to ever hope to detect the mushy waves emitted.

But if you have two much more massive objects—like, say, neutron stars, the über-dense cores of stars that have previously exploded—they do generate waves that we can see.

In fact, we have! Kinda. In 1974, a binary neutron star system was discovered by astronomers Joseph Taylor and Russell Hulse. These two massive objects orbited each other very rapidly, once every eight hours or so. As they do, they emit a tiny bit of energy in the form of gravitational waves. That energy comes from the orbital energy of the stars themselves, so as they emit gravitational waves, they lose orbital energy. The orbit shrinks, and the time it takes the two stars to revolve around each other drops. Over time, that “orbital decay” can be very precisely measured … and it was seen! Not only that, it matched the prediction of GR perfectly.

The measured orbital decay of the two neutron stars (red crosses) matches the mathematcial prediction (smooth line) extremely well.


Taylor and Hulse won the Nobel Prize for this. And they only detected gravitational waves indirectly. They saw how the loss of energy by emitting the waves affected the stars’ orbits. But they didn’t detect the waves themselves.

So How Did LIGO Do It?

Gravitational waves come in many shapes and forms, but what they all do is infinitesimally distort the shape of space. But how do you measure that? It’s not like you can hold a ruler up between two objects and measure how their distance apart changes when a wave passes through …

… right? Oh, wait. It turns out you can.

Enter LIGO: The Laser Interferometer Gravity-Wave Observatory. LIGO is actually two facilities, one located in Washington state and the other in Louisiana (jointly operated by Caltech and MIT). Neither is what you might think of as an astronomical observatory: They each consist of very long pipes arranged in an L-shape. At the far end of each 4-kilometer-long pipe is a mirror.

One of the LIGO facilities seen from the air.


A very powerful laser sits near the vertex of the L, where the pipes meet. It sends out a pulse of light into a special mirror that splits the beam, sending half of it down one pipe, and the other half down the other pipe. Each mirror reflects is beam back down the pipe, and then they’re recombined inside a detector.

Here’s a video (credit: NSF) describing how this works:

Let me add what’ll seem like a bit of a non sequitur to help make this clear: Have you ever sat in a tub of water and sloshed your body back and forth? If you time it just right, you can amplify the wave of water coming back at you, making it splash higher. You can also time it just right so that you move in a way to negate the wave coming at you, too.

The motion of your body sets up the first wave. When you move again, you make a second wave. It the crest of the first wave hits the crest of the second wave, they amplify each other. If the trough of the second wave hits the crest of the first one, they negate each other.

This is called interference. Where the waves amplify it’s constructive interference, and where they negate each other its destructive interference.

Light is a wave. If the laser and the two mirrors in LIGO are set up just right, then the two beams will interfere with each other when they reach the detector. Interference patterns, called fringes, can be seen when you do that, and the exact pattern seen depends, in part on the exact distance between the mirrors. If one mirror moves a tiny bit relative to the other, then the fringe pattern changes.

See where this is going? If a gravitational wave passes through LIGO, one mirror will move a teeny tiny amount relative to the other, and that will create a change in the fringe pattern. Fringes are sensitive to extremely small changes in mirror position, so this is a great way to look for gravitational waves.

How sensitive? A typical gravitational wave will move the mirrors by about 0.0001 times the size of an atomic nucleus! So yeah, they’re sensitive.

LIGO has two such setups located thousands of kilometers apart to help distinguish real astronomical sources from things like earthquakes, trucks driving by, and so on. LIGO first went into operation in 2002. Over nearly a decade it looked but found no gravitational waves. In 2010 it shut down for a significant upgrade, making it far more sensitive. This new configuration started observing in September 2015.

Apparently, all this time they were right on the threshold of detection. Once the more sensitive rig was employed, it didn’t take long before they hit paydirt: This signal was detected on Sep. 14!

What Did They See?

Now we’re ready to put all this together.

Imagine two black holes in a very tight orbit around each other. Both are massive, and whipping around each other at a large fraction of the speed of light. They’ll be pouring out gravitational waves, ripples in spacetime expanding away at the speed of light. It’s possible LIGO could detect something like that, but there’s more to this.

As the black holes whirl madly and emit gravitational waves, they lose orbital energy. Like the neutron stars that got Taylor and Hulse their Nobel, the orbit of the two black holes shrinks. They revolve around each other ever faster.

This change in their orbital rate affects the waves they emit. The frequency of the waves (how many are emitted per second) depends on how rapidly the two objects orbit each other. As the orbit of the black holes shrinks, they revolve around each other faster, and the frequency of the gravitational waves goes up. But, since the black holes are moving more rapidly, they emit even more waves, so they lose energy faster, so they emit even more waves.

This is a runaway effect. The black holes get closer and closer together, whirl around each other faster, emit more and stronger gravitational waves with a higher frequency … until the black holes eat each other! They merge, becoming one (slightly larger) black hole.

Here’s an animation showing this phenomenon (using white dwarfs instead of black holes):

What LIGO sees when this happens is the signature of the gravitational waves, with the frequency going up all the time. Sound is also a wave, and the frequency of sound waves is what we interpret as its pitch. A higher frequency sound has a higher pitch; it’s a higher note, if you prefer.

As the black holes get close to merging, their frequency rockets up. In the sound analogy, it’s like they’re singing a note, and as they get closer the note gets stronger and stronger and higher and higher. At the end, the increase in pitch is so rapid it goes way up extremely quickly: This is a chirp.

Literally, a chirp is a sound where the frequency increases rapidly (listen to one here). So the signature of two black holes (or neutrons stars, or even white dwarfs) inspiraling and merging is a chirp in the gravitational waves. If you catch that, you’ve witnessed the black holes at The Moment Of Truth, when two become one.

And one last bit that boosts confidence: The signal from the merging black holes was detected in the Washington state detector first, then in the Louisiana detector 7 milliseconds later. That delay was due to the waves moving at the speed of light across space!

This merger is simply astonishing. It’s one of the most catastrophic events in the Universe, and until just last year we were essentially blind to it.

LIGO has opened our eyes.

What’s Next?

With this detection by LIGO, a new era in astronomy begins. In many cases, the gravitational waves are emitted from objects we can’t see directly, like black holes merging, or binary neutron stars. Sometimes, though, these objects do emit visible light. A supernova—an exploding star—can emit gravitational waves. Even more dramatically, when two neutron stars merge and form a black hole, they release not just gravitational waves, but also a huge flash of energy in the form of gamma rays and even visible light. These gamma-ray bursts occur in the Universe every day, and we see them all the time. If we can also detect the emitted gravitational waves from them, it will help astronomers understand these bizarre and incredibly violent phenomena.

Even better, we’re not starting fresh. Last year, the European Space Agency launched LISA Pathfinder into space. LISA stands for Laser Interferometer Space Antenna, and is basically a super-LIGO in space. LISA Pathfinder is a benchmark mission to test the very sophisticated technology involved. If it works, then a full-up LISA may be launched in the coming years, which will consist of three separate detectors separated in space by millions of kilometers. Its sensitivity will be far, far higher than LIGO’s, and will rip the field of gravitational wave astronomy wide open.

Whenever we find a new window into the Universe—radio waves, gamma rays, even the invention of the telescope itself—immense wonders have been our reward. In the vast majority of cases we had no clue what was waiting for us once we peered outwards in a new way. Stars numbered beyond imagining, galaxies packed together clear across the cosmos, planets, nebulae, and even an eventual understanding of how the Universe came to be, how it changes, and how it will evolve in the future.

The treasures, the beauty, the knowledge, have fundamentally changed how we humans see ourselves and our place in the Universe. And here we stand, our hand on another window, ready to throw it open.

What will we see when we look through?

Further Reading

Feb. 10 2016 12:41 PM


Uluru is a gigantic sandstone monolith in the Australian Outback. And I do mean gigantic; it’s 3 kilometers (10,000 feet) across its widest point, and juts up an imposing 350 meters into the sky.

Well, imposing from the ground. From space it looks decidedly different.


The image above is from Proba-1, a European Space Agency satellite designed as a testbed for new tech. Proba-1 is less than a meter on a side and when it launched in 2001 had a lot of cutting-edge tech on it (paving the way for the later generation Proba-V sat). It has a high-resolution camera onboard capable of seeing objects just 10 meters across, which is pretty good for a camera 600 kilometers above the Earth.

Uluru is amazing. Australia’s northwest desert used to be a shallow sea. The seabed was made of iron-rich sand, and Uluru was part of a huge alluvial fan, sediment deposited from streams or rivers that spread out into a fan shape. This built up many layers of sand, deposited over the seasons. Eventually the sea dried up, leaving behind all those layers, now compressed into rock, and colored red as the iron oxidized, forming rust.

About 400 million years ago, mountain ranges in that area were thrust up due to tectonic forces. This uplifted the layers of sandstone, tilting them from horizontal to very nearly vertical. Most of those uplifted blocks have eroded away, but Uluru still remains. The scoring, the lines you see across the top are actually the layers of sandstone deposited by those prehistoric rivers! The layers have different strengths, and erode at different rates, causing the striations. If the layers hadn’t been tilted upward, we’d only see one layer, the top one.

Geology is weird.

But miserly—it uses the same processes all over the world. As I read about the geologic history of Uluru I had to laugh: It’s very similar to what happened outside my window! The western part of the U.S. was also once a shallow sea with iron-rich sand (the remains of the ancestral Rockies, mountains that built up and eroded away long, long ago). The sea dried up, the current Rockies pushed their way skyward, and uplift exposed the layered sandstone. The city of Boulder’s west end is graced by the Flatirons, immense and iconic sheets of reddish rock cracked and pushed to dizzying angles by the powerful forces under the Earth’s surface.

You can see examples of this uplift all over town; I took this picture while biking north of Boulder:

Boulder geology
Layers of sedimetary rock north of Boulder. They were originally deposited horizontally, but the Rockies pushing up through the crust cracked and uplifted the layers, tilting them.

Phil Plait

You can see the layers of rock, pushed up at an angle. Keep tilting until they’re vertical, and multiply the size by a gajillion, and you get Uluru.

The Proba-1 image is grayscale, but other images from space show its color. I’ve been to Australia twice, but never to this area. It’s a long way from anywhere, but if I go back, I may have to put this on the agenda. To see such a thing from up close must be truly magnificent.

Feb. 10 2016 9:00 AM

NASA’s 2017 Budget Request: The Good, the Bad, and the Same Old Same Old

NASA and the White House have announced their proposed budget request for the fiscal year of 2017 (the government year starting Oct. 1). As usual, there’s good news and bad news.

First, let me be clear: This is not NASA’s actual budget. Every year, the space agency gets together with the president’s staf,f and they hammer out a budget based on what they want to do. Usually there are some guiding principles, like beefing up commercial spaceflight, getting back to the Moon or going to Mars, things like that.


In the meantime, in Congress, the House works out its own separate budget for NASA (and everything else in the federal government). Once approved in committee, it goes to the floor for approval by all the representatives, and then that version of the budget bill goes to the Senate. They then work out their own version, both sides of Congress hammer out their compromises, and then finally, they present that to the president as part of the federal budget to approve or deny.

Got it? So the budget we’re hearing about now from NASA is just a request to Congress and will very likely undergo changes, some big and many small. But change it will.

Also, all of this is a bit of a hot take from me, a quick look first impression of what’s what. As time goes on we’ll get more of a sense of what these numbers mean … and what Congress is likely to say about them (for another take on all this, see my Alan Boyle’s summary at GeekWire, Casey Dreier’s at the Planetary Society and also Jeff Foust’s at SpaceNews).

So, given all that, what have we got? Let’s look at the biggies first.

Artwork depicting an SLS launch, sometime in the future.


Overall, the budget requested totals slightly more than $19 billion. That’s down from last year’s enacted budget of just less than $19.3 billion but is also the highest request the president has ever made. So yay? Kinda? As always, I’d like to see NASA’s budget doubled. Remember as you read everything below, NASA’s budget is less than 1 percent of the federal budget. That’s a good thing to bear in mind.

Space Launch System, or SLS, is the heavy lift launch rocket NASA is developing, and Orion is the capsule being developed with it that will carry humans into space. The requests for the two this year are $1.31 billion and $1.12 billion respectively. This can be compared with what was actually enacted for them last year: $2 billion, and $1.27 billion. That means the request is far less than last year’s funding, down by $690 and $150 million.

Personally, I am no fan of SLS. I’ve written about this many times; I don’t think this rocket is really needed, and it costs so much that very little money will be left over in NASA’s budget to actually do anything with it after it’s built (it’s like buying a car so expensive you can’t afford groceries).

However the Senate is very pro-SLS (some joke it’s actually the Senate Launch System).  Last year, the requested budget from the president for SLS was $1.36 billion, and Congress added $650 million to it! So I expect this request, like last year’s, will be heavily modified (added to) by Congress. This past year, Orion was actually funded at a higher amount than last year’s request as well.

Commercial Crew and Cargo (the part that funds companies like SpaceX and Boeing to take supplies and humans into space) gets a total of about $2.76 billion. The crew funding is down a bit from last year, but it looks like overall this will be a robust amount to fund these companies (the Commercial Spaceflight Federation agrees). I’m all for this; we rely on Russians right now to get our astronauts up to the International Space Station, and that is a terrible situation to be in. Commercial Crew gets mixed support in Congress; some Congress critters support it strongly, while others do everything they can to slow it down and feed more to SLS.

As for science, that’s hit and miss. Astrophysics got a bump of $51 million over last year to $781 million, which is nice (the James Webb Space Telescope got less funding than last year, but that’s part of the planned-for needs of the mission; less money is needed next year than for the previous year). Heliophysics (studying the Sun) got a bump of just under $50 million to almost $700 million, so that’s good too.

Bizarrely, planetary science got slashed again by the White House. It drops from $1.63 billion to $1.52 billion, a cut of over $110 million. Mind you, this is the division that produced the successful flyby of Pluto last year. You may remember that. It’s a bona fide mystery why, year after year, the president’s request continues to try to cut what’s arguably the most successful part of NASA, both scientifically and in the public eye. My only hope is that, as they have done in previous years, Congress steps in and puts that number back to where it should be.

Jupiter's moon Europa; with a liquid water ocean beneath its surface, this may be our best bet to look for life on (or under) another world.

NASA/JPL-Caltech/SETI Institute

Incidentally, as Casey Dreier at the Planetary Society points out, a lot of this cut goes into the budget for the Europa mission (to Jupiter’s icy moon that has an ocean of water under its surface). It’s looking like the White House wants to fund an orbiter, but Congress has been clear on wanting a more expensive lander mission (I do too, duh). It’s not clear what rocket will be used there either; the Senate will want to use SLS, of course, while the president will want the Atlas V. I have my doubts that relying on SLS, a rocket that won’t be useable for nearly a decade, is a good bet. However, it would be able to launch a much more ambitious Europa mission and get it to Jupiter faster. So, I’m conflicted here and have no obvious resolution to this mess (unless SpaceX gets their Falcon Heavy operating soon).

Earth science gets a boost this year in the request, up more than $110 million from last year, to just more than $2 billion. I wonder what will happen there when this gets to Congress? The total number may stay about the same (it did last year), but I would bet funding will be rearranged by Congress, since Earth science covers missions that study climate change. We know how the GOP-controlled Congress feels about that.

While Sen. Ted Cruz, R-Texas, doesn’t directly control NASA money, he can influence what NASA does; mind you he is running for president under the banner of cutting government spending. He also has been beating the drums hard to promote his anti-science agenda. His counterparts in the House feel the same way, so I’m fairly confident this part of the budget will see some changes.

And maddeningly, NASA’s education arm suffers another big cut in this request, from $115 million enacted last year to $100 million. Madness. For some reason, the president’s office has been slashing this part of the budget year after year, and that’s just a terrible idea. Plain and simple. I worked in the education community using NASA funds for several years, and I saw first hand how much of an impact it had. NASA’s outreach efforts are part of why people correctly think of NASA as the shining example of humanity’s vision of exploration. Cutting that effort makes zero sense.

So for now, there we go. Again, these are some quick looks with my opinion added; I reserve the right to modify my opinions as more facts come in. We’ll see.

And again, remember how tiny a fraction of the federal budget NASA gets. Imagine if, instead of squabbling over pennies, we funded our space exploration at the level that it actually needs. What wonders would we see, what benefits would be reaped on Earth, how could we add to our compendium of knowledge about the Universe?

Per politicus, ad astra.

Feb. 9 2016 9:15 AM

New Study: Yup, Thermometers Do Show Global Warming Is Real

A common claim by climate change deniers is that scientists have been “altering” ground-based temperature data to make it look like the Earth is warming. This claim—which is not just wrong, but exactly wrong, as I’ll get to in a sec—has gotten more traction than most others offered by the forces of anti-science.

Rep. Lamar Smith, R-Texas, has been using this false claim as a blunt hammer against scientists in NOAA, for example, holding hearing after hearing trying to pin charges of conspiracy on them. But of course he’s wrong and is wasting huge amounts of taxpayer money pursuing a lie. As I’ve written before, the scientists aren’t “altering” the data, they’re correcting them.


A new paper has come out reinforcing this. Researchers from Berkeley, the University of York, and NOAA have looked at the temperatures recorded at stations across the U.S. They assessed the corrections being applied to the data and have confirmed their accuracy. In other words, despite Smith’s claims, the techniques the scientists are using to calibrate the data are solid.

The basic idea is this: There are temperature stations all over the U.S., and many have been in use for more than a century. However, over the years, some have been moved, replaced, or their environment has changed. This, of course, changes the temperature they record.

To account for that, scientists apply a correction to the data to make sure that they are comparing apples to apples when looking at modern measurements versus older ones. But how do they know if the corrections are accurate?

Actually, there are quite a few ways, but in the new study the researchers looked at more modern stations that are known to be quite accurate and compared them to the data from nearby older stations during the 12-year period where the two different systems were both in operation at the same time. As was expected, the uncorrected data from the older stations didn’t match the newer ones well. However, when the corrections were applied, the older stations did in fact match the newer ones much better. This shows that the corrections being applied are in fact making the data more accurate.

The average monthly temperature anomalies (deviations from an average) from 2004–2015. The new station readings are in green; the old ones using the correction are in orange. Note how good the fit is.

Hausfather et al.

Smith and his allies want you to think that scientists are nefariously altering the data, but that’s not the case. Calibrating data isn’t “altering” it. Think of it more like editing typos and bad grammar. Once those are gone, you get a far better picture of what’s actually happening*.

Interestingly, there are still some residual errors in the older measurements even after adjustments—that’s not too surprising; in the real world it’s almost impossible to completely correct such issues. But what’s funny is what the researchers found: Even after adjustments, the older systems still tend to underestimate maximum (and average) temperature trends compared with the newer systems during the overlap period)—consistent with other research that found the same trend.

This puts lie to Smith’s claims again. If scientists are altering the data to make it look like the planet is warming up, why would they underestimate the temperature trends?

The answer is obvious: They aren’t trying to make the planet look like it’s heating up. The planet is heating up, and they’re measuring that. That’s what the data are telling us, that’s what the planet is telling us, and as long as our politicians in charge are sticking their fingers in their ears and yelling “LALALALALALA” as loudly as they can, we’ll never get off our oil-soaked butts and get anything done to prevent an environmental catastrophe.

head in the sand
Not pictured: oil-soaked butt.


*Zeke Hausfather, the lead author on the new study, wrote about the methodology they’re using in an article for Skeptical Science last year, which has the details on all this if you’re interested.

Feb. 8 2016 9:30 AM

A Small Asteroid Will Definitely Miss Earth on March 5. But by How Much?

In the “don’t panic” category, the small(ish) asteroid 2013 TX68 will definitely miss the Earth when it swings by our fair world on March 5.

The orbital mechanics on this are pretty clear; it certainly won’t hit us. The thing is, it’s not clear by how much it’ll miss us, and the range is a bit uncertain: It’ll pass somewhere between 17,000 to 14 million kilometers from Earth.


Yeah. That’s a big gray area. So what gives?

TX68 is a rock roughly 30 meters across*, and that’s pretty small as these things go. That means that at any respectable distance from Earth it’s essentially invisible; too faint to detect. We can only see it when it gets close enough to Earth to be visible to telescopes, and that window of opportunity doesn’t last long.

It was discovered in October 2013 when it was about 1.5 million kilometers away (nearly four times farther than the Moon) and was only observed over a three-day span before it became too difficult to see. That makes getting an accurate orbit for TX68 really hard. I’ve written about this before:

Think of it this way. Imagine you’re an outfielder in a baseball game. You see the pitcher throw the ball, and the batter swings. It’s a hit! But one-tenth of a second after the batter makes contact, you close your eyes.
Now, based on the fraction of a second you saw the ball move, can you catch it?
I would be willing to bet a lot of money you won’t. You weren’t able to watch the ball long enough to get a good fix on its direction, its speed, its position. It could land next to you, or it could fall 40 meters away, or it could be knocked right out of the park.
The only way to catch it would be to keep your eyes on it, observe it as long as possible until you can be completely sure of where its headed.

That’s the problem; with only three days of observations of TX68 back in 2013, it’s impossible to predict exactly where it will be when it passes the Earth in March. What you get is a fuzzy prediction that puts it near the Earth, with a range of likely distances based on that. The closest it can get is 17,000 kilometers, but it could pass us 14 million kilometers away.

TX68 orbit
The best approximation we have at the moment for the orbit of TX68. It's not clear how far away it will be when it passes us (in the diagram, both Earth and TX68 orbit the Sun counterclockwise). The position marked for the asteroid was for early February.


From a position of “Ohmygod is this thing gonna hit us?” we’re pretty safe. From an astronomer’s position of “Hey I want to observe this thing for myself and help nail down its orbit” it’s frustrating. That uncertainty means we’re not even really sure where it’ll be in the sky at a given time. Our best bet is to use wide-field telescopes, scan the most likely areas it’ll appear, and hope for the best.

And I hope the best is what we get. TX68 is a near-Earth asteroid, passing pretty close to us; it could impact us in the future. As it stands right now the odds are extremely low for the next few decades … but that’s based on the orbit as we know it now. After this pass we should increase our understanding of the orbit substantially.

To be honest, that won’t be easy. If it does pass only a few tens of thousands of kilometers away, the Earth’s gravity will change its orbit (it also may pass within 20,000 kilometers of the Moon, further altering the asteroid’s orbit), making it even harder to predict its future position.

All of this underscores our need to have more eyes on the sky. An impact from a TX68-sized asteroid is pretty rare; statistically speaking it only happens every few centuries. But smaller rocks are more common, and impacts from them more frequent; the Chelyabinsk event of 2013 was caused by a rock a mere 19 meters across and impacts from something that size happen on the every-few-decades timescale. The more ‘scopes we have scanning the skies, the more likely we’ll be able to see such a rock in advance, and the more time we’ll have to do something about it… assuming we get around to figuring out just what to do.

* Correction, Feb. 9, 2016: I originally wrote that TX68 was 100 meters across; it's actually 100 feet or 30 meters across (the error is my fault, but oh how I wish everyone used metric!). That changes the statistical frequency of impact from millennia to centuries. 

Feb. 7 2016 9:30 AM

Music of the Spheres

When space and astronomy based time-lapse animations started becoming popular a couple of years ago, all it took was some cool imagery to get noticed. But over time we’ve seen a lot of such animations, and (unless the footage is really dramatic or unusual) it’s tougher to draw attention now.

Nicolaus Wegner—who has created quite a few stunning storm time-lapse animations I’ve featured on the blog—knows this. He wanted to make a video highlighting “… how important and amazing our Earth is.” Using footage from various space probes and astronauts on the International Space Station, he put together this short video. “Final Frontier,” to do so.


Mind you, we’ve seen a lot of this footage before. What makes this special? Hint: Listen to the music as the images roll by.

The music Wegner used is called “Falling Short” by Danny Odon. It’s electronica, and as the video starts (with images of the Sun, Pluto, the comet 67/P Churyumov-Gerasimenko, and more), it’s eerie, driving. But when the video cuts to shots of Earth it becomes more melodic, fluid, and soothing.

Then, building a bit in tension, it cuts to very odd and disturbing tones as the video shows the weird moons of Saturn in motion seen by the Cassini mission, reminding us that our solar system is a bizarre place once we leave the confines of Earth. It’s a clever bit of storytelling, allowing the music to set the tone and manifest the theme without having to overtly state it.

I’ve said this many times, but the choice of music is critical to short videos like these. I’m a soundtrack geek, and when I watch movies, TV, and short films like this one, I find myself paying as much attention to the music as the footage. Working together, they inform our brain far more than either can on their own.

Feb. 6 2016 9:15 AM

Edgar Mitchell, 1930–2016

I'm very saddened to write that we’ve lost another Moon walker: His family just announced that Edgar Mitchell, Apollo 14 astronaut, died on Thursday.

By coincidence, he died on the 45th anniversary of his mission, just one day short of the anniversary of the date he landed on the Moon.


All 12 men who walked on the Moon are heroes. They risked their lives to go where no human had gone before, and our planet—our species—is the better for it. What Mitchell and his fellow astronauts did will forever be a part of history. Each mission was an amazing story, and I urge you to read about Apollo 14 (and also read Andy Chaikin’s fantastic A Man on the Moon, too, for insight into the Apollo program and the people involved).

To be fair, too, Mitchell will also be known for some of his more unconventional beliefs. For example, he was a vocal advocate in the UFO community. He believed that aliens were visiting Earth and that there’s a government conspiracy to cover it up. As you can imagine, he and I didn’t see eye to eye on that.

However, that doesn’t mean he believed in all conspiracies. I met Mitchell a few years ago at a gathering of space enthusiasts, and chatted with him briefly about people who believe the Apollo Moon landings were faked (I haven’t talked about it in a while, but a little while ago I wrote extensively on the subject). I asked him if he had ever run into Bart Sibrel, one of the biggest mouthpieces for that silly idea (yes, the guy Buzz Aldrin punched).

Mitchell laughed, and said that Sibrel came to his house on false pretenses (a Sibrel forte) and once inside started making accusations of fakery, demanding Mitchell swear on a Bible that he did in fact walk on the Moon. Mitchell told me he did swear on the Bible, and then said he immediately—and literally—kicked Sibrel out of his house.

That still makes me smile.

And a lot of people give Mitchell grief for conducting ESP experiments while on Apollo 14. That sort of thing was pretty popular in the late ’60s and early ’70s, and a lot of the experiments going on weren’t well conducted. Mind you, I don’t think such extrasensory powers exist; the evidence is at best very shaky and the cases that get popular tend to be fraudulent. However, I also have no problems in general testing such claims, and having three men out in space, tens or hundreds of thousands of kilometers from Earth does make for a decent control setting. I don’t really blame him for trying, even if he may have been biased toward believing in it.

My point? People are complicated. If there’s a bigger testament to the reality of the fields of science, mathematics, and engineering than walking on the Moon, then I’m unaware of it. But that didn’t prevent him from still having beliefs that were at odds with some the principles of those same fields. But in that sense he was no different than the rest of us. We all have them, to one degree or another.

I think it’s OK to remember that, especially when talking about the life and career of someone like Mitchell. It highlights the complex nature of how we think, of what makes us who we are. Of how it makes us human. Reflecting on ourselves is a natural response to hearing of someone’s death, and if his legacy is in part to remind us of what it means to be human, then that’s not such a bad one.

Ed Mitchell on the Moon
Ed Mitchell, on the Moon.


And one final note. Mitchell was the sixth human to step foot on the Moon. With his death, there are now only seven people alive who have left bootprints there. I hope that we see humans walking on the Moon once again, and soon; soon enough that the Apollo astronauts themselves can witness it. We owe them that much.

Feb. 5 2016 9:30 AM

Gigantic Space Telescope’s Main Mirror Now Complete

OK, first, JWST is the successor* to Hubble, an observatory optimized for viewing the Universe in infrared wavelengths, outside what our human eyes can see. This will make JWST very sensitive to distant galaxies, low-mass stars, planets orbiting other stars, and about a zillion other very interesting astronomical objects.


And second, JWST’s mirror isn’t like other telescope’s, where you have a giant solid piece of glass. Instead, JWST’s mirror—which is 6.5 meters across!—is made up of an array of 18 hexagonal segments, each about 1.3 meters wide.

Hubble vs JWST
Hubble's solid circular mirror (left) versus JWST's honeycomb.


There are lots of advantages to this design; each mirror can be made much lighter weight than 1/18th of a big mirror, and mass matters when you’re launching a ‘scope into space. The mirrors are made of beryllium, which is very lightweight, so each segment has a mass of only 20 kilograms (45 pounds)!

Also, the entire assembly folds up like origami, allowing the completed mirror to fit inside the payload space of an Ariane 5 rocket. Finally, each mirror has its own independent actuators on the backside, allowing each segment to be individually adjusted to ensure perfect focus for the ‘scope.

The assembly of the main mirror is a big milestone for the observatory. It’s fantastically complex, and nothing quite like this has ever been flown into space before.

Oh, another thing about the mirrors: They’re coated with gold. Gold reflects infrared light very well (most glasses don’t), so it makes a great coating. Each mirror has a layer just a tenth of a micron thick; that’s 0.001 times as thick as a human hair! Even though it’s covering about 25 square meters in total, the layering is so thin that the total mass of gold used isn’t much, about 50 grams. The gold used is ultra pure and not cheap, but the kind of pure gold you can get on the market runs about $40/gram right now, so at that price JWST has only about two grand worth on it. That’s probably the least expensive part of the entire mission.

A lot of the work done on the mirror segments was performed at Ball Aerospace, just down the road from me in Boulder, Colorado. When the assembly was finished in 2012, they had a small press event, and I was able to attend. The highlight of that day was seeing one of the flight mirrors (that is, one of the actual segments that will fly into space as part of JWST’s main mirror) from just a couple of meters away! It was in a clean room, and I got a shot of it through a door:

JWST mirror segment
One hexagonal segment of the JWST mirror; note the reflection of the door and window through which I shot this photo. CLick to enaurumenate.

Phil Plait

Yes, that’s me reflected in the hexagonal mirror. That was a pretty cool day.

The final assembly of the mirror segments on to the "back plane" was accomplished this week at NASA's Goddard Space Flight Center in Maryland. The entire process took several weeks.

I’ve had varying opinions on JWST over the years; it will be a magnificent and ambitious space telescope, and will revolutionize infrared astronomy in much the same way Hubble did for visible (and ultraviolet) light. But it’s also had massive cost overruns and is far, far behind its original schedule, and that’s bruised NASA’s overall budget (and politics) for other astronomical missions over the years.

But while that still aches a bit for me, that doesn’t affect what this mission will hopefully accomplish: Give us the clearest, deepest, and best view of the Universe we’ve ever had at these wavelengths.

Congratulations to everyone involved in getting this important step done! And keep up the good work; there’s still a ways to go before the scheduled October 2018 launch.

*Over the years I’ve seen a lot of people refer to JWST as the “replacement” for Hubble. That’s just not correct; for one thing they look at different parts of the electromagnetic spectrum, so JWST can’t replace Hubble in that regard. Plus, if all goes well, Hubble will still be in use when JWST gets to work, so we’ll have both telescopes to peer into the Universe. One of the things I’m most excited about is having both of them look at some of the same objects at the same time; many phenomena are far easier to understand once you get different eyes looking at them.

Feb. 4 2016 9:15 AM

Is This the Biggest Spiral Galaxy in the Universe?

Nature does love spirals.

From the cream floating in your coffee cup to hurricanes to galaxies themselves, spirals form on a vast range of scales. They may be for different reasons (coffee and hurricanes have faster rotation in the center, winding up the arms, whereas galaxies form spirals from a more subtle and complex effect that acts like an interstellar traffic jam), but when you have stuff that spins, spirals can arise naturally.


But how big a spiral can you get? Our Milky Way galaxy is pretty beefy, one of the bigger spiral galaxies in the Universe. It’s roughly 100,000 light-years across, or a quintillion kilometers. That’s a lot of kilometers.

Don’t go bragging to your friends just yet though. It turns out spirals can get bigger. Way, way bigger.

The galaxy pictured at the top of this post is called Malin 1. It’s faint; so dim it was only discovered in 1986, and was the first discovered in a class of galaxies called low-surface brightness spiral galaxies. Most spirals are pretty bright and easy to see, but LSBs are much fainter. Despite that, they can grow to huge sizes.

I’ve known about Malin 1 for a while, but it hadn’t really registered with me one way or another. That changed instantly when I saw a new paper about it, which was featured on the American Astronomical Society’s Nova site, where notable discoveries are highlighted.

I saw the photo of it and nodded in admiration; it’s a very pretty and interesting spiral. But then I saw the distance, and my brain did a double take. Malin 1 is 1.2 billion light-years away.

“Wait,” my brain said, shaking itself. “What? That can’t be right!”

But it is: 1.2 billion light-years is a tremendous distance. If it’s that far, and that big in the image, it must be huge. Freaking huge.

Yeah. My brain was right. Malin 1 is more than a half-million light-years across.

Holy Haleakala. That’s ridiculous. It’s hard to explain how big that is. The Milky Way is titanic, and Malin 1 dwarfs it.

Malin 1 and Milky Way
That's a big galaxy.

Galaz et al., 2016/NASA/JPL-Caltech

Here, this’ll help. I added a drawing of the Milky Way into the Malin 1 image, roughly to scale. Malin 1 is easily five times wider than the Milky Way.

That’s very interesting indeed. How do you get galaxies that big? We know most (if not all) galaxies grow by eating smaller galaxies (literally the smaller galaxy gets ripped apart by the bigger galaxy’s gravity, its gas and stars ingested by the bigger beast), or merging with galaxies of comparable size. We can see the leftover remnants of smaller galaxies the Milky Way has eaten, and in a few billion years we’ll double in mass when the Andromeda galaxy collides with us.

But it’s not clear how Malin 1 (or other low surface-brightness galaxies like it but somewhat smaller) grew to such enormous proportions. And why isn’t it brighter, like other, smaller spirals? Digging through some papers on Malin 1 I found that it’s not forming stars as rapidly as the Milky Way; stars are born in the Milky Way at twice or more the rate they are in Malin 1. That may be why it’s dimmer (fewer massive stars born means less light coming from the galaxy). But I don’t think anyone really knows.

I’m usually not all that impressed by cosmic records; finding the most distant this or the biggest that. I’m more excited when that record tells us something. The most distant galaxy tells us how young the Universe was when the first galaxies formed, for example.

In the case of Malin 1, it’s telling us how physics operates on the biggest scales. Spirals can form in galaxies five times bigger than ours … and somehow that may also be correlated with the galaxy being dim.

There are also some peculiar features in Malin 1; you can see a long straight feature pointing away from it at about the 11 o'clock position (another one, on the opposite side of the galaxy center, is likely a background galaxy coincidentally superposed). This feature may be a long stream of gas and stars pulled out from Malin 1 by a close encounter with another galaxy off the edge of the picture. These long features were invisible in previous images but can be seen here thanks to the power of the giant Magellan 6.5 meter telescope, which took the image (and some sophisticated techniques used to enhance the image as well). A Hubble image taken a few years earlier only hinted at the far-flung spiral arms, showing you just how important the telescope size can be (Hubble’s mirror is 2.4 meters across).

It’s not surprising to me that our census of the Universe is still incomplete; there are lots of things so far away—or close by and so dim—they’re invisible to our prying eyes. But it’s still something of a shock when we find objects this flippin’ huge that have managed to evade us for so long.

It’s a sobering lesson. The Universe is almost incomprehensibly vast, and still holds many of its secrets dear. What else have we missed?