The entire universe in blog form

Aug. 26 2014 9:30 AM

Noctilucent Time-Lapse

Man, that’s a weird title.

But it’s accurate enough. I’ve written about noctilucent (literally, “night shining”) clouds a few times recently. These weird, high-altitude clouds appear to be more common in recent days, and it’s not clear why (global warming is one culprit). But they are visible just after sunset and before sunrise, lit by the Sun that to us on the ground is below the horizon. They take on a shimmering, silvery cast, and are quite stunning.

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Astrophotographer Göran Strand caught some in late July, and took some fascinating all-sky time-lapse video of them that shows their motion:

Neat! You can see lower-altitude (aka “normal”) clouds moving in from the east, contrasting with the much higher noctilucent ones.

These are still on my to-do list of must-see clouds, together with roll clouds and a big scary mesocyclone forming over the Midwestern plains. And an aurora, come to think of it. And a total solar eclipse, sure. And finding my own meteorite.

I’m not picky; any order of these will do. As bucket lists go, this seems doable. I have my feet on the ground ... but my head in the clouds.

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Aug. 26 2014 8:00 AM

“Everybody, Remember Where We Parked”: Choosing a Landing Site on a Comet

The Rosetta spacecraft successfully rendezvoused with the comet 67/P Churyumov-Gerasimenko in early August, and has been tagging along with the weirdly-shaped double-lobed dirty iceball ever since. It’s been taking extraordinary pictures and making lots of other measurements, sending them back to the Earth over 400 million kilometers away.

Scientists are poring over the data; not just to study the comet for science, but also to prepare for the next big step in the mission: Setting the lander Philae down on the surface.

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Choosing a landing spot is difficult. There needs to be something interesting going on there, since the lander is loaded with scientific instruments that will poke and probe its immediate environment (including drilling down into the surface and analyzing what it finds). But the lander needs to be kept safe, too. That means the terrain (cometain?) needs to be relatively smooth; boulder fields may prove to be somewhat hazardous. But the comet spins once every 12 hours, and lighting conditions can change radically also, affecting the long-term science planning. I expect the surface itself will need to be thought through carefully; the lander will anchor itself using harpoons shot into the ground, so a light fluffy material may not provide the traction needed.

After looking over the images sent back, an initial ten landing potential landing sites have been narrowed down to five. The regions are indicated in the picture at the top of this post (note that the letters are not a ranking; the original ten were just lettered A – J). The OSIRIS camera was used to get better close-ups of the regions for examination. Here’s spot A:

Rosetta landing spot A
I'm not sure I could parallel park there.

Photo by ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

This one is on the bigger of the two lobes, and has the advantage of being a good place to observe the smaller lobe, too. This looks like a place where loose material has flowed down, given how smooth it appears. However, there could still be small depressions of other hazards here, so the examination continues.

Here’s landing spot B:

Rosetta landing site B
Warning: Backing up will cause extensive tire damage.

Photo by ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

I’m guessing they won’t go with this one; the presence of so many large boulders means landing could be difficult. But the area above the boulder field does look pretty smooth.

These are images taken at one given time, and more are being taken to investigate the areas under different lighting conditions as the comet rotates. That will highlight things like bumps, pits, and so on, as the shadows change.

The decision will have to be made soon; Philae is scheduled to deploy in November. Rosetta is already dropping down toward the comet; the initial 100-km standoff distance has been lowered to 60 km, and it’ll get closer yet before sending Philae on its way. I’m getting pretty excited by all this! The images and data we’re getting now are already quite amazing, but they’ll get far better as the probe nears the surface.

And then, finally, as Philae heads for the comet, we’ll see what one of these things looks like up close and very personal.

Aug. 25 2014 7:45 AM

SpaceX and ESA Suffer Launch Problems

It hasn’t been the best week for uncrewed space launches.

On Friday, Aug. 22, 2014, SpaceX was testing a new configuration of its F9R vertical launch and landing rocket—essentially a Falcon 9 first stage booster adapted to land on its tail after launching a payload into space—when something went wrong. It was already a few hundred meters in the air when the software onboard detected the malfunction and aborted the mission by exploding the rocket. This is done to prevent the possibility that an out-of-control rocket might fly off and injure someone.

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To be clear: This was an uncrewed rocket, no one was hurt, and it was a test flight to try out some new tech. Footage of the launch and explosion is easy to find online; here’s one from BBC Brasil:

I’ll note that most of the video I found was copied from other sources, and original footage is difficult to find. Hopefully SpaceX will release better video soon. They did issue a statement:

Earlier today, in McGregor, Texas, SpaceX conducted a test flight of a three engine version of the F9R vehicle (successor to Grasshopper). During the flight, an anomaly was detected in the vehicle and the flight termination system automatically terminated the mission.
Throughout the test and subsequent flight termination, the vehicle remained in the designated flight area. There were no injuries or near injuries. An FAA representative was present at all times.
With research and development projects, detecting vehicle anomalies during the testing is the purpose of the program. Today’s test was particularly complex pushing the limits of the vehicle further than any previous test. As is our practice, the company will be reviewing the flight record details to learn more about the performance of the vehicle prior to our next test.

They haven’t yet said what exactly went wrong. SpaceX will provide another update when the flight data has been fully analyzed. I have to wonder how certain members of Congress will react when the news is released …

Anyway, I think Elon Musk, CEO of SpaceX, said it best:

SpaceX was scheduled to launch AsiaSat 6 into orbit on a Falcon 9 today, but after the test problem this new launch has been pushed back to Wednesday, Aug. 27. The hardware involved is very different, but they want to make sure there’s no risk to the AsiaSat 6 mission.

In other news, a European Space Agency launch didn’t go according to plan either. The mission was to put the first two Galileo global positioning satellites into orbit, but the rocket put them into the wrong orbit. It’s not clear that the satellites’ on-board propellant is sufficient to get them into the correct orbit, either, which means they would be “deemed useless.”

Galileo is the European version of the American GPS satellites, with 30 satellites set to eventually comprise the entire fleet. This failure to get them into orbit is a serious issue; the same rocket system is planned to launch four more pairs, but that will have to be put on hold until the problem is resolved. A dozen more satellites are planned to be launched by a different rocket sometime later.

So, this has been a rough week for space travel, but these things happen. No one was hurt, which is good, and hopefully the problems will be analyzed, understood, and quickly fixed.

This is, after all, rocket science.

Aug. 24 2014 8:00 AM

Call of the Universe

Kids these days.

When I was wee lad, we had Bugs Bunny, and we liked it (because he’s brilliant). But these whippersnappers now have this Animaniacs stuff, with the Yakko and the Wakko and the Dot.

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Buuuuuut, Yakko did sing a great song about the size and scale of the Universe in one episode, so when my old friend Marian Call asked me for some help in updating the lyrics to reflect what we’ve learned about the cosmos since 1993 (when that episode came out), how could I not?

Here’s the song. Marian’s got a killer voice, and she does the song good. Some of the numbers may sound off to you, but in fact if you think about them you’ll figure out why we went the way we did (like the diameter of the solar system; don’t forget the Oort Cloud!). As for the number of planets, well, I have my thoughts on that.

If you like the Universe song you can download it for a buck, and Marian has a whole album of her singing classics you can buy, too. Many of them are very geeky, so I suspect most of you reading this will like them.

You’ll like her video for “Good Morning, Moon,” too:

Aug. 23 2014 8:30 AM

Indonesian Volcanoes and Galactic Vistas

Coincidences are funny.

I recently got an email from astrophotographer Teoh Hui Chieh, who was sending me several photos and a time-lapse animation she took near the volcano Mount Bromo in Indonesia. The shots are lovely, as you’ll see in a moment.

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That very same day, about an hour or two later, I got an email from astrophotographer Thierry Legault, who was sending me several photos and a time-lapse animation he took near the volcano Mount Bromo in Indonesia. The shots are lovely, as you’ll see in a moment.

But what the what?

Yup. Coincidence. They don’t know each other, but they were both in that location around the same time, and shot remarkable images of the land- and skyscape.

Here is Hui Chieh’s time-lapse animation:

And here is Legault’s:

There’s no losing here; both are gorgeous. I love the shots of the volcano (Mount Semeru) venting steam as the stars whirl above it, and the lights from cars illuminating the fog below. If I saw such a scene in a movie I would have thought it fantasy! But it exists.

The image at the top of this post is from Hui Chieh. I’m so used to seeing star trails in the Northern Hemisphere, it took me a moment to realize that shows the south celestial pole! That’s impossible to see north of the equator, but this scene is at a latitude of about -8°, just south of the equator, so the southern sky’s pole is just barely above the horizon.

You can explore more of Hui Chieh’s photography on Flickr, and Legault’s (who has been on this blog many, many times) at his website.

As for the coincidence, well, they happen. It’s a big world, with countless things happening all the time. People who say, “I don’t believe in coincidences” (usually in the movies, when it so happens that events were not coincidental) in general just don’t have a good grasp of large number statistics. Given world enough, and time, unlikely events occur. Like having two world-class photographers send me pictures from the same spot at the same time. I’ll take it.

Aug. 22 2014 8:00 AM

The Ring Nebula, Still Mysterious After All These Years

Of all the planetary nebulae in the sky, none is more celebrated than M57, the Ring Nebula. Lying about 2,400 light years away toward the constellation of Lyra, it’s bright enough to be seen in small telescopes, and when long exposures are taken, quite a lot of detail comes out.

Astrophotographer Rob Gendler knows his way around a digital astronomical image. He has been making a habit of creating incredible photographs using multiple observatories, both in space and on the ground, professional and amateur. He took observations from the Hubble Space Telescope, the Large Binocular Telescope, and the monster 8.2-meter Subaru telescope, and combined them to make a stunning image of the Ring. I literally gasped out loud when I saw this:

Ring Nebula
The glorious Ring Nebula, one of the finest examples of a dying star in the sky. Click to greatly embiggen.

Photo by NASA, ESA, and C. R. O'Dell (Vanderbilt University) and Robert Gendler

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(You really want to see that in full-res because wow.)

This extraordinary image combined visible light observations with ones taken in the infrared, well outside what our eyes can detect. Generally speaking the inner regions are emitting in visible, and the outer ones (shown in red) are infrared.

Back in the day, it was thought that the Ring was a simple shell, a thick soap bubble of gas cast off by a dying star, illuminated by the star’s fierce ultraviolet emission. Over time, though, we’ve realized it’s more complicated than that. Far more complicated.

Astronomers argue today over the details of the three-dimensional shape of this gas cloud. One group thinks the inner parts are barrel-shaped, and we’re looking down the long axis. Another model is that the inner ring is a much squatter, flatter barrel shape, with elliptical lobes of material poking out the ends. Both models argue that the “flower petals” are lobes of material, like balloons, pointing in slightly different directions, and the very outermost ring is a thin spherical shell, probably gas that was originally outside the star that got snowplowed as the gas from the star expanded and slammed into it. If we could see the Ring from the side, it would look very different; more like the Ant Nebula or possibly M2-9.

ring nebula model
This is a schematic showing one of the models of how the Ring Nebula must really be shaped. What we think of as the ring itself is just a short, barrel-shaped structure in the middle of a larger cloud, and we're looking down the barrel. The caption made me laugh, but really, this is simplified. Nature is complicated.

Diagram by C. R. O'Dell et al, from the paper

It was fascinating to read those papers; I studied planetary nebulae for my master’s degree (and in a limited extent for my Ph.D. as well). Determining their 3-D structures is maddeningly difficult, because we have limited information with which to figure them out. For example, looking end-on at an American football makes it look like a circle. Without knowing the angle we’re viewing it from the real shape may be hard to ascertain. The same sort of thing happens with planetary nebula. You have to really examine subtle details to tease out what the nebula is actually doing.

But I love this! Here is one of the loveliest and best-examined objects in the sky, and yet we’re still trying to figure out its exact shape. The thing is: We can. It’s possible. We just have to keep using new methods to observe it, use all the tools we have to dissect it, and lay out all these pieces of evidence to reassemble them into a picture we can understand.

Images like Gendler’s help this along, giving us a deep overview of the Ring. Over time, we’ll get to know this gorgeous example of a dying star even better, and from there gain a better understanding of how stars like our own Sun will die. It’s all part of science, and the joy of trying to grasp the Universe.

Aug. 21 2014 11:30 AM

Impact for a Lifetime

Talking to the public about science and rationality is an odd way to spend your life.

It can be maddening, when you go against those who oppose reality: homeopaths, anti-vaxxers, global warming deniers, young-Earth creationists. For those of us who love the Universe the way it is, going up against that tsunami of nonsense is a grueling and unending task.

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Worse, in some ways, is wondering if what you’re doing is actually helping. Sure, I get traffic on my blog, or retweets, or “likes” on various social media. But those metrics are ephemeral, fleeting. Are there any indications of a more permanent effect?

Yes. Yes, there is. I recently got a note from a woman named Kristin Ormiston on Facebook. I know this sounds a bit self-serving, but bear with me. She had this to say:

Hi! I just wanted to message you to tell you I think you're amazing and inspiring! And I was encouraged to send you these pictures of the tattoos on my ankles, inspired by a quote of yours.

The pictures are these:

skeptical tattoo
"Teach a man to reason; he'll think for a lifetime."

Photo by Kristin Ormiston, used by permission

Oh. Wow. If you’re looking for some sense of permanence in what you do, someone getting something you said tattooed on herself is a pretty good sign.

The art in her tattoo represent queen chess pieces, with lotuses on top. As she told me, “The queen chess piece has the most freedom of any piece on the board. Intelligence and seeking knowledge is what I consider true freedom.”

That’s a pretty good quote, too.

The quote from me—“Teach a man to reason, and he’ll think for a lifetime”—is from my “Goals of Skepticism” talk I gave a few years ago. It’s had a bit of limelight; it was a Reddit banner, featured on a coffee mug, and used in a lovely Symphony of Science video (where I also give the quote’s context).*

I liked the phrase when I came up with it, but had no idea it would resonate so strongly with so many people. I’m glad it did, and I still stand by the idea. After all,

The mind is not a vessel to be filled but a fire to be kindled.

Plutarch said that, nearly 2,000 years ago. We’re still learning, still struggling, to do as that phrase teaches, but the fact that we still know it after all these centuries is a sure sign of its impact.

*As I mention in those earlier posts, the sexist phrasing of the quote bugs me. But it’s based on the aphorism, “Give a man a fish and he’ll eat for a day; teach a man to fish and he’ll eat for a lifetime.” I already was changing the phrasing, and if I changed “man” to “person” it seemed to me that the connection to the original aphorism would be lost. In the end I kept the original phrasing to keep the connection apparent.

Aug. 21 2014 8:00 AM

Dating a Star ... a Few Hundred Thousand, in Fact

Globular clusters are too cool. For one thing, they’re gorgeous. I have proof!

IC 4499: A globular cluster’s age revisited
The spectacularness of the globular cluster IC 4499. Click to enapiarianate.

Photo by ESA/Hubble&NASA

That is IC 4499, a tight ball of tens or hundreds of thousands of stars located roughly 60,000 light years away. This image was taken by Hubble, and besides being spectacular, it also was used to nail down the age of the cluster, which until recently has been a bit controversial. This is another reason globulars are cool …

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Getting the age of the cluster is possible because globulars have a very helpful characteristic: The stars are all the same distance away. That means if a star is brighter than another in the cluster, it really is more luminous. That makes comparing the stars directly to each other easier.

At first it was assumed that all globulars are very old—as old as the Milky Way itself, 12 billion years or so—and that all the stars in each were born at the same time. But it gets a bit more complicated. Some, it turns out, clearly have stars that are old, mixed in with ones that are younger. The thinking is that these clusters are more massive, could draw in more gas over time, and then could have a second bout of star formation after the initial one.

The trick to getting the age for a cluster is that stars age at different rates. More massive stars burn through their nuclear fuel faster, so they run out before their smaller, more miserly brethren. When that happens the core of the star contracts and heats up, and the outer layers respond by inflating hugely, like a hot air balloon. The heat from the interior gets spread out through the much larger surface area, so weirdly the star gets much brighter but also much cooler. We call it a red giant (or a red supergiant if the star is particular massive).

IC 4499: A globular cluster’s age revisited
Detail in the cluster (taken from the right side of the image above). Note how many faint stars can be seen ... and far more distant background galaxies can be seen right through the cluster!

Photo by ESA/Hubble&NASA

That’s the key. If you measure the stars’ colors, the ones that have run through their fuel and turned (or are currently turning) into red giants become very obvious. Theoretical models are pretty good at showing just how old the stars are that are right at that point in their lives, so that in turn must be the age of the cluster.

IC 4499 has always been a problem here. It has an intermediate mass between the lower-mass globulars that have a single population of stars and those heavier ones with two stellar populations. Knowing its age would be very helpful to nail down the difference between the two. Different studies have come up with different ages for it, with pretty large uncertainties, too.

The good news is that the Hubble observations easily cover the stars that are starting to turn in IC 4499, and the telescope’s ability to accurately resolve all the stars really nails down the age: IC 4499 is 12.0 ± 0.75 billion years. It’s old.

This helps. Astronomers like to study extremes, since that tells us what physics is doing at the edge of what it can do. But we also need to figure out intermediate cases, too, if we’re ever to have a fully filled-in picture of what’s really going on in the Universe. IC 4499 is another piece of that puzzle for which we’ve managed to find its place.

Aug. 20 2014 11:45 AM

Our Curiosity

I haven’t written about our laser-eyed nuclear-powered red-planet roaming friend in a while. But the Curiosity rover recently celebrated its second year on Mars (which is really just over one Martian year on Mars). It’s still rolling along—literally—heading for its ultimate target: Aeolis Mons, aka Mount Sharp, the 5.5 kilometer-high peak in the center of Gale Crater, Curiosity's landing site.

Of course, it’s finding a lot of fun souvenirs along the way, and doing amazing science. Caltech put together a nice video as a retrospective of the past two years, as well as a look forward to what it will do soon.

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It’s narrated by a couple of folks who might sound familiar, too. I won’t give it away (but it’s on the YouTube page show notes).

Nice. I have a public lecture I give about Curiosity, and it’s one of my favorites to give of all time. The human effort that went into building, launching, landing, and using this machine is nothing short of Herculean, and still it marches on. It’s a triumph, and I quite seriously choke up during the talk every time. I’m so proud of what we can do.

Congratulations to everyone who is involved with Curiosity and also to those who are building the 2020 rover too. Whenever I see Mars in the night sky, I see it as more than just a red dot: It’s an entire world, and one we’re just now starting to explore.

Aug. 20 2014 8:00 AM

Did I Say 30 Billion Tons of CO2 a Year? I Meant 40.

Every now and again a global warming denier will say that humans aren’t putting much carbon dioxide into the air, and it’s less than a lot of natural sources. I’ve pointed out that in fact, humans throw about 30 billion tons of it into the atmosphere every year, 100 times as much as volcanoes do. I got that number from a paper published a few years back.

Well, I just found out that paper is out of date. Guesss what the more accurate, current number for the human-made CO2 pollution put into the air every year is?

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40 billion tons.

Yeah. 40. As in billions of tons. 40.

That number comes from an assessment made by Le Quéré et al. in a paper measuring the total carbon budget for the planet in 2013. I found out about this new, updated number when I wrote about the launch of NASA’s Orbiting Carbon Observatory, or OCO. I mentioned the older number in the post, and got an email from David Crisp, OCO’s science team leader (!) correcting me.

It’s almost impossible to grasp what 40 billion tons means. A cubic kilometer of water weighs a billion tons, but it’s hard to imagine a cube 3.5 kilometers (2.2 miles) on a side—the equivalent amount of water weighing 40 billion tons. The largest class of aircraft carrier weighs about 100,000 tons, but picturing 400,000 of them still strains the imagination (not to mention vaporizing them into the air every year).

It’s a vast amount.

Funny, though, it’s small compared with the total mass of the Earth’s atmosphere, which is a staggering 5 x 1015—5 quadrillion— tons! By mass, this extra CO2 is only about 0.0008 percent of the Earth’s total air.

But it adds up. By volume, CO2 is about 400 parts per million (ppm) of the atmosphere, or about 0.04 percent. How much are we adding? Looking at the Keeling Curve, which measures the concentration of CO2 in the air, we’ve added about 20 ppm in the 10 years from 2000 to 2010—that’s 2 ppm per year.

keeling curve
The Keeling Curve, measuring atmospheric carbon dioxide. The trend is pretty obvious.

Graph by the Scripps Institute of Oceanography, UC–San Diego

So, that 40 billion tons of extra carbon dioxide we dump into the air every year is accumulating at a rate of 2 parts per million when you look at the entire atmosphere.

That sounds pretty small. But is it?

I wish. For some things, it doesn't take a lot to make a huge difference. As doctors will tell you, dose makes the poison. Four hundred ppm sounds like a small amount, but this concentration of carbon dioxide in our atmosphere is enough to raise the average temperature of the Earth significantly … and we’re putting more of it into the air every year.

Forty billion tons worth. That’s why the planet is heating up. That’s why the climate is changing. That’s most likely why we’re seeing more extreme weather, hurricanes getting stronger, droughts drier, forest fires more intense.

This is our fault, and it’s also most definitely our problem. There is hope … but we need to get our heads out of the sand together and take action. Now.

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