The entire universe in blog form

Oct. 1 2014 12:01 PM

Rocky Snow

Boulder snowfall.
Mount Meeker and Longs Peak got a decent snowfall on Sept. 30, 2014. Click to tectonicate.

Photo by Phil Plait

Mount Meeker, left in the image above, just got a dusting yesterday, but Longs Peak, to the right and behind Meeker, got a bit more. Some of the mountains to the south and west got a goodly amount, too.


We've had very bad droughts and floods here in the Boulder, Colorado, area over the past few years. Here's hoping for a nice, cold, regular snowy winter.  

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Oct. 1 2014 7:30 AM

Say Hello to Our Quasi-Moon, 2014 OL339

Quick: How many moons does the Earth have?

You might be forgiven for saying “one,” but it turns out the question isn’t all that easy to answer … because it depends on what you mean by “moon.”


Of course, we have one moon, the one we call the Moon. It physically orbits the Earth, so it counts. In this case, what we firmly call a moon would orbit inside what’s called the planet’s Hill sphere, a region around the planet where the planet’s gravity dominates over everything else.

But there are other orbits that make it look like an object is orbiting the Earth, but it doesn’t really. There are subtly different flavors of objects like these, but one kind orbits the Sun in elliptical orbits, with an orbital size and shape just right that they take almost (but not quite) exactly one year to go around the Sun once. Typically their orbits are elliptical, taking them closer in and farther out from the Sun than the Earth.

This is precisely the case with 2014 OL339, a 150-meter (or so) diameter rock discovered serendipitously in July by a team of asteroid hunters. Its orbit is highly elliptical; it crosses the orbit of Venus and gets out as far as Mars. It’s also slightly tilted compared with the Earth’s orbit by about 10°.

The orbit of asteroid 2014 OL339. Even though it's elliptical, it has very nearly the same period as Earth.

Diagram by NASA/JPL-Caltech

However, the numbers work out such that it takes—get this—364.92 days to circle the Sun once. Sound familiar? That’s only a few hours less than the Earth’s orbital period (one year, of course). When two objects orbit with periods very close to the same number (or simple multiples, like one taking exactly twice as long as the other) we say they are in resonant orbits.

OL339 is in such a resonant orbit. Mind you, all by its lonesome it just orbits the Sun on an ellipse like a gazillion other such rocks; remove the Earth and it’ll orbit pretty much as it does now (that’s another reason we say it’s not a proper moon of the Earth). But, because of the complex way motions add together, from Earth, OL339 looks like it orbits us, moving backwards relative to the stars (and, I suppose I have to note, it has essentially no chance of ever impacting Earth).

Cruithne orbit
The motions of Earth and Cruithne add together to make it appear as if the latter is in a kidney bean or horseshoe shaped orbit.

Diagram by Jacowa, via wikipedia

In fact, its motion in space looks more like a kidney bean because of this, as shown in the graphic here. In this case the animation shows the path of the weird asteroid Cruithne, which is another object that mimics being a moon. They don’t always stay in orbits like these; over time the gravitational poking by the Earth can alter their orbits, and eventually they wind up moving away from Earth. OL339 should be Earth’s quasi-satellite for about a thousand years in total; it’s been around for centuries already, and may not stick around for more than about 165 more years.

I know, this is confusing, but it turns out objects like these are important. Some start as objects that were in longer, less attached kidney-bean orbits that then tightened up over time. Others started as Trojan objects; sharing Earth’s exact orbit but ahead or behind it by 60°. Some were just passing by but can, over time, wind up temporarily becoming quasi-satellites as their orbits change ever so slightly due to Earth’s gravity.

What I find particularly interesting about these objects is that due to these weird resonances, they don’t necessarily move very rapidly relative to the Earth. Most asteroids whiz by us at dozens of kilometers per second, but these quasi-moons don’t move nearly so rapidly. That means they would make good targets for exploration; changing the velocity of a rocket takes a lot of fuel, so going to an object that isn’t moving as quickly is easier (and leaves more available mass for instruments or, hopefully, people).

Who knows? We have 165 years or so to visit OL339 before it moves off, which should be plenty of time. And there are others, too; three true quasi-satellites (called (164207) 2004 GU9, (277810) 2006 FV35 and 2013 LX28) and a handful more with slightly farther flung orbits (like Cruithne). In some cases, asteroids like this are easier to reach even than the Moon! I do want us to go back to the Moon, and to push on to Mars … but visiting these rocks may prove to be an excellent intermediate step. I’d love to see us doing something like that in the next few years.

Tip o’ the dew shield to New Scientist.

Sept. 30 2014 7:30 AM

What Lurks Beneath the Methane Lakes of Titan?

One of the biggest discoveries made by the Cassini spacecraft is that Titan—the mammoth moon of Saturn—has lakes of liquid methane and ethane on its surface. Radar maps of the surface of Titan confirmed that the north pole is dotted with them, and combined cover far more of the surface of that moon than the Great Lakes do the Earth.

Smooth lakes of liquid natural gas don’t reflect radar waves well, so the maps made of Titan show the lakes as dark. Cassini’s instruments are sensitive enough that they have even ruled out constant waves on the lakes; they would show up as bright streaks in the images. The lakes are extremely smooth.


So what’s going on with the images above? In 2007, radar maps showed Ligeia Mare very near the moon’s north pole, looking pretty much as usual. The lake looks dark, and solid material (land) shows up as white. But in 2012 a new feature appeared, just off shore! It disappeared, but then turned up again in radar maps taken in 2014 … but shaped differently.

What the what? What are we seeing here? Fun answer: No one knows.

Scientists have apparently ruled out errors in the imaging techniques or artifacts in the detector, meaning whatever this thing is, it’s real.

Same as above, but with a newer image from 2014, showing how the event, whatever it is, has changed shape.

Photo by NASA/JPL-Caltech/ASI/Cornell

It could be any number of things. Clearly it’s some transient feature, something that can come and go. That indicates it’s probably not solid land. It could be waves, or some sort of solid material just beneath the surface (methane ice)?

My first thought was bubbles, and I was pleased to see this on the list of candidates. Titan has seasons, and summer is coming for the moon’s northern hemisphere. The warming temperatures could be releasing bubbles buried in sediment under the lakes, for example, or the liquid could be warming up enough to release dissolved gases.

Right now no one knows, which is wonderful. A mystery! And it’s a good one.* Saturn and its system are full of ‘em. But what this does show is that even in the outer solar system, where temperatures reach a balmy -180° C, worlds can still be dynamic, interesting places. So much so that even after 10 years in orbit there, Cassini still has the ability to amaze and delight us.

*I’ll admit I’m still hoping for sea monsters. The biggest lake on Titan is named Kraken Mare!

Sept. 29 2014 12:01 PM

This Is Your MOM’s Mars

Holy. Ares!

THAT is a full-disk image of Mars taken by India’s Mars Orbiter Mission, or MOM. It was just released this morning and shows nearly an entire hemisphere of the planet.


It’s gorgeous. There’s so much to see! North is to the upper left (roughly the 11:00 position), and the pole looks like it’s covered in a cloudy haze [Update (Sep. 29, 2014 at 17:40 UTC): Ah, according to my friend and fellow science writer Carolyn Collins Petersen, that's a dust storm brewing there.]. The huge, lighter-colored region just to the right and above center is called Arabia Terra, a 4,500-kilometer stretch of uplands that is one of the oldest terrains on Mars. It’s hard to tell from this wide-angle shot, but it’s heavily eroded and covered with craters.

Just below it is a long dark feature called Terra Meridiani (“Meridian Land”; though you could fancifully call it “Middle Earth”). The rover Opportunity is there, still roaming around and poking at the rocks there. This whole area shows evidence that is was once under water.

Nestled in the northern part of Terra Meridiani is the crater Schiaparelli, which is more than 460 km across! That’s huge, far larger than the crater left by the dinosaur-killer impact here on Earth. Straight up from it in Arabia Terra you can also see the crater Cassini (also more than 400 km wide), and to the right, just inside the dark region called Syrtis Major, is the crater Huygens, which is about the same size as Schiaparelli. The astronomers Cassini and Huygens studied Saturn, which is why the Cassini probe is named what it is, and the lander probe it sent to the moon Titan is named Huygens. Those astronomers really get around.

I could go on and on; you can see Hellas Basin as a smooth, butterscotch-colored area to the lower right just on the edge, and the ices of the south pole at the bottom. There are craters galore, and all sorts of wind-eroded areas that so many scientists will happily spend the rest of their lives studying.

But for me, right now, what makes me sigh in awe is the overall perspective of this picture. We’re seeing the entire face of the planet here, a perspective we don’t always get from our probes, sent to study Mars in detail. And the added touch of it not being fully lit—you can see the day-night line, called the terminator, cutting across the planet to the upper left—really drives home that what we’re seeing here really is an entire world, a huge expanse of territory just calling out for us to explore and understand.

There’s a lot of solar system out there to look at, and it fills me with joy to know we’re doing just that.

Sept. 29 2014 8:00 AM

Where Will We Find Extraterrestrial Life First?

Here’s an interesting question: Where will we find life outside Earth first? In our solar system, on worlds like Europa, Enceladus, Titan, or Mars; signs of it from an exoplanet; or possibly even signals from intelligent civilizations?

Science communicator Katrina Jackson sat down with two astrophysicists—my friends Michelle Thaller and Neil Gehrels—to talk about exoplanets and the search for life. It’s a short video but a very intriguing one.


(Note: This is one part of a longer conversation that covers more topics).

I wonder about this question as well (who doesn’t?). It’s a bit complicated, because we don’t know if life exists outside Earth in any of these ways. But for fun let’s assume it does. Which would happen first?

Right now, we’re not terribly well equipped to do a thorough search for life on worlds in our solar system. The rovers on Mars don’t have the right equipment to unequivocally detect signs of life. Anything they find short of macroscopic fossils would probably be indirect (say, chemicals in rocks indicative of biological processes). The evidence they find probably wouldn’t be conclusive either, so we’d be arguing for a long time over whether it was due to life or not. (This isn’t a guess; results from tests done by the Mars Viking landers are still argued over, and those tests were done in the 1970s.)

It’s the same problem for exoplanets. I’m excited about WFIRST, which is a proposed space telescope that can directly image exoplanets and get spectra of them (JWST will, too), which can detect the chemical signatures of elements and molecules in the atmospheres of the planets. If they find oxygen, that would be pretty spectacular! As Michelle says in the video, oxygen is highly reactive, and the best way we know to have it in an atmosphere at decent levels is through life. But as Neil points out, there may be things we don’t know, and the arguing will continue (and most likely justifiably so) even when the data are in hand.

As for SETI, they mention Seth Shostak, who has predicted that if intelligent life exists in the galaxy, and is broadcasting, we’ll find them in the next couple decades. It’s a bold prediction, based on current tech and our ability to improve our techniques. If we find a signal, what then? I wonder. If it’s a strong, clear signal (like in the movie Contact) then we’ll be pretty sure what’s what. But what if it’s weak, or noisy, or ambiguous in some way? We’ve had false hopes before (as Neil mentions in the video). It could very well be that what we find isn’t as clear as we hoped.

Because of all this, in the end, I’m not sure which way will produce the first, best results. And that’s assuming life is out there to begin with! The obvious solution is to keep looking in as many ways as we can. If life is out there, and it’s recognizable, it only makes sense to keep our eyes—and our minds—open.

Sept. 28 2014 7:00 AM

Japanese Volcano Eruption Caught on Video … VERY Up Close and Personal

If you’ve ever wondered what my nightmares are like, they pretty much go like this.

On Sept. 27, a group of hikers was enjoying the fall weather on the Japanese volcano Mount Ontake. Suddenly, the volcano erupted, letting loose an incredible pyroclastic flow, a torrent of superheated ash that barrels down the slopes of the volcano like a thundering wall of death. The hikers tried to get away, but the flow was far faster … still, one of them managed to get video.


(Yes, it's vertical, so turn your head. And give the videographer a break, they were all literally running for their life.)

My heart was pounding in my throat watching that; ever since I started reading about volcanoes years ago, pyroclastic flows fill me with visceral terror. They are implacable and unyielding; my friend and geologist Mika McKinnon calls them “rolling clouds of murder.” It is almost beyond imagination that the hikers survived. In fact, given how many people were on the mountain that day, it’s truly remarkable anyone survived. However, there have been no confirmed deaths as I write this (one had been reported but was subsequently retracted). Update, Sept. 28, 2014 at 15:00 UTC: Well, damn. I'm very sorry to add that overnight reports say that least 31 people have been killed by the eruption. Here is more information on what may have happened, written by volcanologist Erik Klemetti.

I’d write about the science behind all this, but Mika has already done an outstanding job on io9.

I love volcanoes; they are fascinating and something about them draws me in. I will happily travel to see more … but as I do, something like this will always be at the very least at the back of my mind. As long as it isn’t literally at my back.


Sept. 27 2014 7:30 AM

A Night of Science and Silliness

I have good news if you like fun things! And if you live somewhere near the San Francisco Bay area.

On Oct. 25 I’ll be at the Castro Theatre to do not one but two science comedy events: BAHFest and the Quiz-O-Tron 9000! Both are part of the Bay Area Science Festival, a weeklong celebration of science. Or, in the case of these two events, the mocking of it. To wit:


1) BAHFest is the Festival of Bad Ad Hoc Hypotheses, which is the brainchild of that ginger fiend Zach Weinersmith, creator of the Saturday Morning Breakfast Cereal comic. The gist is that people come up with terrible science-based just-so stories to explain something, then present it to the audience and judges. To give you an idea of how this goes, read the SMBC comic that inspired it.

I will be a judge at this, and I will be harsh but fair. (Note: I will be neither.) The keynote speaker is Matt Inman, who draws The Oatmeal, so c’mon. This will be amazing.

For tickets and such, go to the BASF BAHFest page. I know Zach and I will have books and stuff to sell and sign after the event, as will Matt and probably others.

b) Quiz-O-Tron 9000 is a snarky quiz show hosted by my friend and noted MRA enemy Rebecca Watson. She asks panelists about current science news topics, and the person with the most points at the end of the show (generally arbitrarily assigned by a judge with a tenuous grip on events) wins. I’ve done this a few times at DragonCon, and it’s a lot of fun (see these photos for evidence of such funnery). It’s also decidedly adult, so fairly warned be thee, says I.

I’ll note I am the Reigning Champion of the Universe for this game, and I have the belt to prove it. I’ll be bringing the belt with me, only so I can mock the other panelists when I take it home with me again.

I’m really excited by this. This will be a fantastically fun night, so don’t miss it.

*Correction, Sept. 30, 2014: In the original picture caption, Adam Isaak's last name was misspelled.

Sept. 26 2014 7:30 AM

The Oldest Known Star in the Universe

Astronomers have found the oldest star in the Universe. Well, kinda. It’s the oldest one we know of. At least the oldest one we know of for which an age has been reliably measured.

OK, enough caveats. What’s going on?


Some stars are young; we see them being born now. Some are middle-aged, like the Sun, which is about 4.56 billion years old. It’ll be good to go for another 6 billion years or more (though more on that in a moment).

And some are old. Very old. Up until now, the oldest star that has had a reliable age measured for it is about 13.2 billion years old. It was already old when the Sun was just starting to fuse hydrogen into helium.

But astronomers have just published a paper about a star that is even more elderly: HD 140283, which appears to be 14.3 billion years old.

Now, before you start quoting that number for the next edition of the Guinness Book of Cosmic Records, you might want to note that the Universe itself is only 13.82 billion years old. Clearly, something must be off here.

The answer is that the age of the star is off. That takes a moment to explain.

When the Universe was young, just a few hundred million years old, it was a bit simpler. The main stuff floating around was hydrogen and helium. There weren’t a lot of other elements yet because there hadn’t been enough stars to make them! Elements heavier than helium* were created in the first stars, and then scattered into the cosmos when those stars exploded. These elements were then seeded into clouds of gas, which formed the next generation of stars.

Astronomers call all elements heavier than helium “metals,” which is dumb, but that’s what we’re stuck with. And as a rule of thumb, the older a star is, the fewer metals it has in it. We can measure the amount of such materials in a star by taking high-resolution spectra of it. Surveys have identified lots of stars with low metallicity, and three such stars were specifically targeted for the research, including HD 140283.

The advantages of looking at this star are many. For one, it’s near the Sun (less than 200 light years away), so the distance can be determined very accurately using parallax. Its location in the sky was clear of galactic dust, which can interfere with observations. And for another, it’s finally—finally—nearing the end of its life.

That’s important. A star like the Sun spends most of its time fusing hydrogen into helium in its core. But eventually that hydrogen fuel runs out. The core starts to shrink under its own gravity and heats up. That sends its temperature through the roof (so to speak), and it heats up the layers of the star above it. That causes them to expand, and so the star begins to get bigger. Eventually it becomes a red giant, but for a while, as it expands, it’s called a subgiant. This won’t happen with the Sun for several billion more years, but with HD 140283 it’s just starting to happen now. That’s convenient timing; we have excellent physical models for how stars behave when they turn into a subgiant, and that depends on their temperature, their brightness, and their age. Very careful analysis of the star has yielded the age measurement, and that’s how they got that it’s 14.3 billion years old.

But there are a number of difficulties with getting the age this way—it depends on factors like (oddly) how much oxygen is in the star, how much dust is between us and it, and other things. In the end, they calculate their error bars as about ±0.8 billion years.

What that means is that their formal calculation gives the age as 14.3 billion years, but 13.5 billion is just as likely the right number. It’s possible it’s younger than that, but not as likely.

Any scientist looking at that would then be perfectly happy concluding that the star is younger than the Universe. I am. And I’ll note that the previous record holder, called He 1523-0901, had an uncertainty that was a bit bigger than for HD 140283. All things considered, it’s reasonable to conclude HD 140283 is somewhat older.

So is it the oldest star in the Universe? That seems unlikely. It’s a big, big Universe, and the odds of the actual oldest star being a) in our galaxy at all and 2) that close to the Sun are essentially zero. Most likely we’ll find older stars the more we look. But since this isn’t an exact science what we’re likely to find is not a single oldest star, but a bunch of stars that are all about the same age to within uncertainty. And they’ll all be just a few hundred million years younger than the Universe itself.

And that’s pretty cool. The goal here isn’t to break the record, it’s to collect data for lots of stars so that we can understand what things were like back when the Universe was a wee baby, and how stars have changed in all the eons since.

When you step back and think about that for a moment, I hope the hair on the back of your neck stands up. Using astronomy and physics, we can understand the very nature of the Universe itself, from the moment it came to be, through all its adventures since, and then predict what it will be like in the vast, deep future.

Science! I love this stuff.

*Some lithium was also around, but in very tiny quantities, and it’s also easily destroyed inside of stars. So for the purposes of this discussion it doesn’t really count.

Tip o’ the dew shield to my friend Bond, Howard Bond, who is one of the authors on that paper.

Sept. 25 2014 7:30 AM

MAVEN’s Mars

As I write this, India’s Mars Orbiter Mission has been orbiting the red planet for just about a day, and NASA’s MAVEN for only three. I haven’t seen any images from MOM yet (UPDATE: see below), but the Mars Atmosphere and Volatile Evolution spacecraft took ultraviolet images just eight hours after achieving orbit, and they’re breathtaking.

MAVEN and Mars
MAVEN sees Mars breathe: Ultraviolet images of the planet's atmosphere will allow scientists to understand it better. Click to enaresenate.

Photo by Laboratory for Atmospheric and Space Physics,University of Colorado;NASA

Mars has an atmosphere, thin, but there. And it has different components to it, seen in different wavelengths (colors) of UV light.


Hydrogen is the lightest element, and extends the farthest off the planet. Shown here colored blue (representing the shortest wavelength of UV), you can see it extends well off the planet’s surface (Mars is 6,800 kilometers—4,200 miles—across, for scale). Oxygen (in green) is heavier, and sticks closer. There isn’t much of it on Mars, and what there is comes from water (which is where the hydrogen originates as well) and carbon dioxide. I suspect the crescent pattern is due to limb brightening; near the edge of the planet we’re looking through more atmosphere, so the oxygen emission is more apparent there.

The red panel is reflected sunlight, and you can see a brighter ring near the pole that is either from clouds—Mars has those too, though very thin—or ice. The panel on the far right is the composite of all three images, an amazing portrait of our neighbor.

I literally sighed in amazement when I saw there; they’re lovely and fascinating and just so odd. Mars is such a weird little world.

But weird is in the eye of the beholder. MAVEN will orbit Mars and take scientific observations for at least a year, and we’ll get to learn quite a bit about the atmosphere of the planet as it does. Mars used to have thicker air and plenty of water; now they’re both almost all gone. Why? Why did Mars evolve so differently than Earth? We know it has to do with Mars not having a strong magnetic field as we do, so the solar wind was able to merciless strip away its air over the eons. But our understanding of the details is still lacking. That’s what we sent MAVEN to find out.

And it joins so many other probes currently examining Mars—including MOM, which I haven’t written much about, but of course Emily Lakdawalla at the Planetary Society has a fantastic article about it. There’s still so much to explore on Mars. And above it. Soon, we’ll have a more complete picture of it, and hopefully understand why, but for the whim of nature, go we.

Update, Sept. 25, 2014 at 14:00 UTC: Of course, between the time I wrote this article last night and the time it posted this morning, MOM released two great shots of Mars. The first shows a view of windswept craters over a bicolored landscape:

MOM's Mars.

Photo by MOM/ISRO

The gray is due to dark basaltic rock, and the red from where the surface is covered in dust rich in iron oxide—rust.

The second shot shows the limb of Mars:

MOM on the edge.

Photo by MOM/ISRO

I love the caption posted from the MOM Twitter account: "A shot of Martian atmosphere. I'm getting better at it. No pressure."

I'm very excited to see what else India's first interplanetary mission has in store for us!

Sept. 24 2014 9:30 AM

Jon Stewart Puts the Heat on Congress

If you ever catch me in a moment of weakness about the weapons-grade dumbosity of global warming denial on the Republican side of the U.S. House of Representatives, it might look a lot like what Jon Stewart did on The Daily Show on the Sept. 22, 2014, show:

It’s become a cliché that majority members of the House Science Committee know nothing at all about actual science (or they do, but choose to ignore it for ideological reasons)—but here on display for all to see is just how ridiculous the reality of it is. What you just saw are long, long debunked denial points being brought up like they are revealed wisdom, along with “gotcha”-style barbs that are transparently, bone-headedly wrong.


And isn’t presidential science adviser John Holdren a freaking ninja in those clips? He easily and smoothly shuts down the salvos of scientific ignorance tossed out by the committee members. For his part, I’m very glad Stewart pointed out the glaring hypocrisy of people like Rep. Larry Bucshon, R-Indiana, who accuses climatologists of faking the science for money, when Bucshon himself is funded quite well by fossil fuel interests.*

Holy oiliness. It’s loathsome enough that Bucshon would choose to simply ignore the agreement of the vast majority of climatologists who know the Earth is warming and that it’s our fault … but to do so while happily taking the Koch brothers' money is really galling.

If I seem upset about this, it’s because I am. It’s like we’re in some sort of alternate reality, a Hollywood spoof of what government is like. But it’s real, and these buffoons are holding up any real chance we have of making any progress about one of the (if not the single) largest problem we as a species face.

There’s an election coming up, folks. Vote. I know there’s essentially no chance that the GOP will lose the majority in the House, but it’s important to get out there and vote, and to get others to as well. If we don’t, then we’re just handing over our future to these people who have their minds firmly closed to reality.

*Correction, Sept. 24, 2014: This post originally misspelled the last name of Rep. Larry Bucshon.