Bad Astronomy
The entire universe in blog form

Oct. 6 2015 9:00 AM

The 20th Anniversary of Exploring Strange, New Worlds

20 years ago, on this very date, the field of astronomy underwent a magnificent revolution.

On Oct. 6, 1995, Swiss astronomers Didier Queloz and Michel Mayor announced they had discovered a Jupiter-like planet orbiting a Sun-like star.


This was the very first time a planet was seen orbiting a “normal” star. Planets had previously been discovered around pulsars; the compact and furiously energetic cores of stars that had exploded. But it’s thought that the planets may have formed after the supernova event that created the pulsar, and besides, pulsars are nothing at all like the Sun.

Still, this new planet, called 51 Pegasi b, was a surprise. A big one! While it had about the same mass as Jupiter, it orbited its host star (51 Peg) in just four days, meaning it was on an orbit a mere eight million kilometers from the star. Compare that to Mercury, our solar system’s innermost planet, which never gets closer than about 46 million km from the Sun.

This meant 51 Peg b was hot, cooking away at a temperature of about 1300° C. No one thought a planet that size could be that close to a star. Did I say the discovery was a surprise? I meant it was a shock, one so profound that it was met with deep skepticism.

As well it should! But its existence was quickly confirmed by team of American astronomers, rivals in the hunt for the first extrasolar planets, as they were once called (we now call them exoplanets).

The planet was found using what’s called the “radial velocity” or reflexive “motion method”. A planet orbits a star due to the star’s gravity. But the planet has gravity, too, so as the planet makes a big circle around the star, the star makes a little circle. In reality both orbit the center of mass of the system, called the barycenter. I describe how this works in my episode of Crash Course Astronomy about the discovery of exoplanets:

As far as we knew at the time, planets like Jupiter had to form far out from their stars, half a billion kilometers or more. Because of this, astronomers who were hunting for exoplanets assumed they would take months or years to make an orbit. They completely missed the presence of 51 Peg b in their data.

Once it became clear these “hot Jupiters” existed, more were found in existing data. Within a few years many more were discovered. It’s now thought they do form far out, but then migrate closer to their star over millions of years. Although they make up only a minority of all exoplanets, these are the easiest to find using reflexive motion; their high mass and close orbit make their signal in the data easiest to see.

Once 51 Peg b was found, the floodgate was opened. HD 209458 b was another hot Jupiter found in 1999, and had an orbit so close to being edge-on that astronomers thought it might actually pass in front of its star, transiting it, dimming its light once per orbit. Careful observations later that same year detected a dip in the star’s brightness (only 1.7 percent!), which gave them the first independent observation of an exoplanet. Any lingering doubts about the existence of these alien worlds evaporated.

The field matured so quickly that NASA launched the Kepler spacecraft in 2009, designed specifically to stare at 150,000 stars to look for transiting exoplanets around Sun-like stars. As of today, Kepler has over 1000 confirmed exoplanets under its belt, and well over 3000 more waiting confirmation.

We’ve seen planets big and small, hot and cold, orbiting small cool stars, huge hot stars, multiple stars, and even in systems with multiple planets.

When I was a kid — heck, when I was in grad school — the only planets we knew of were the ones in our solar system. Using simple statistics, we now think that planets outnumber stars in the galaxy, and that most stars may have planets. There may be tens of billions of Earth-sized planets in our galaxy alone!

But we had to start somewhere. Exactly two decades ago, 51 Peg b gave us that start.

51 Peg star chart
The star 51 Peg is just off the Great Square of Pegasus, which is in the east after sunset for northern hemisphere observers. EarthSky has a finding chart for Pegasus, then you can use this image to find the star.

Map by Sky Safari

The host star, 51 Peg, is close by, just 50 or so light years from us. It’s actually very much like our Sun, just a hair more massive, hotter, and bigger. It’s visible to the naked eye, barely, from a dark site. The constellation of Pegasus is high in the night sky for northern hemisphere observers right now, in fact. If it’s clear where you are, and you have a pair of binoculars, why not take a look at it tonight?

I will. The exoplanet is completely invisible to even the largest of telescopes, drowned by the light of its oh-so-close star. But who knows: Maybe a photon or two from the planet itself will pass into your eye as you look at the star, absorbed into your retina.

The sky may be brimming with planets. We stand on one among billions. And if you look, a small spark, literally the tiniest reflection of one, could become a part of you.

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Oct. 5 2015 11:00 AM

How to Make a Rubber Ducky Comet: Smash Two Comets Together! Carefully.

Why is the comet 67P Churyumov-Gerasimenko shaped like a rubber ducky?*

It was a bit of a surprise when the Rosetta probe, after a decade of travel around the Sun, approached the comet and sent the first decently resolved pictures of it back to Earth. We knew going in that most asteroids and comets just a few kilometers across are oddly shaped; they lack the gravity needed to make themselves spheres, and after 4 billion years of impacts their shape can be decidedly odd.


We even know of a few bowling pin shaped comets, like Hartley 2 and Wild 2. But 67P just reinforced the weirdness of this all with its two lobes mismatched in size and shape.

So, why? What’s going on? Comets are rock, gravel, and dust all mixed together with various ices holding them together, frozen stuff like water, carbon dioxide, and carbon monoxide. Did these weird, dumbbell-shaped comets start off more round and, for some reason, lost more ice in their midsections, leaving behind the two big lobes? Or were they the result of two interplanetary snowballs that collided and stuck together?

New results from the Rosetta team have finally answered this question. 67P used to be two different comets, but they merged to become the bizarre bit of solar system fluff we now know and love.

How? Well, when two comets love each other very much …

Oh wait, no, that’s not it. Well, actually, kinda. Back in May 2015 astronomers came up with a pretty good scenario on how to form a rubber ducky comet. Two smaller comets collide in a slow-speed, grazing impact. Some material is lost, and the two major pieces separate a bit, but the impact was slow enough that they become gravitationally bound. They fall back together, stick, and voilà!

As for the “how do we know?,” that’s more subtle, and quite clever. Rosetta has been orbiting 67P since August of 2014. Over that time it’s taken a vast number of high-resolution images, revealing details of the surface. Both lobes have flat regions all over them arranged like terraces, and the steps in between the terraces show layering; these probably built up layer by layer over time when the comet(s) first formed billions of years ago.

terraces and layers
A close-up of 67P shows flat terraces (colored green here) and layers (red).

Photo by ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; M. Massironi et al. (2015)

If the comet formed as a single object that has since eroded, you’d expect the terraces and layers on both lobes to align so that their flat sides were perpendicular to the center of the comet, somewhere in the neck, plated around it (something like the individual panels on a soccer ball, which all are perpendicular to the ball’s center, or, of you prefer, more-or-less parallel to the ball’s surface).

If, instead, the two lobes formed individually and later merged, then the terraces on each lobe would be perpendicular to the center of their respective lobe.

Using 3-D modeling, the scientists mapped the orientation of the terraces. And what they found is the latter: The terraces align to each lobe individually, not to the center of the comet as a whole. This strongly indicates the lobes formed separately, later merging.

comet map
A 3-D model of the terraces in the comet indicate their orientations, showing the two lobes of 67P formed separately, then later merged.

Photo by ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; M. Massironi et al. (2015)

That is very, very cool. I’ve been curious about this ever since we literally got the first good pictures of the comet. I allowed myself a bit of speculation back then and felt that a low-speed collision between two small comets was unlikely. I guess I was wrong! While space is big, I neglected to consider that time is also long, and over an eon or four collisions may be likely. After all, 67P isn’t the only object like this; we know of quite a few binary and dogbone-shaped asteroids, too.

How about that? The beauty of this, too, is that the answer gives us insight into more than just why the comet is funny-looking. It also tells us about how comets behave, what their formation processes are like, what happens after they form, and, perhaps most interestingly, how often objects in space collide. That in turn helps us understand the history of our solar system in general, as well as how often the Earth itself gets hit by such cosmic debris.

Over time, we do get hit. The rate of such impacts is a good thing to know, so that we can better understand how to prevent them.

After all, we don’t just want to be a … sitting duck.

*Hint: It’s not because it makes bath time so much fun.

Oct. 5 2015 9:00 AM

Ben Carson vs. Ben Carson

Scientist Ben Carson, talking about his own fetal tissue research: "To willfully ignore evidence that you have for some ideological reason is wrong."

Creationist Ben Carson, talking about scientists who understand the Big Bang, evolution, and global warming are real: "I just don't have that much faith," he said. "But they are welcome to believe whatever they want to believe. I'm welcome to believe what I want to believe."


Do politicians ever actually listen to what they say?

Oct. 4 2015 9:30 AM

Marketing Space

I have to admit, I laughed, especially at the “Pluto” part.

Still, I do sometimes worry about the future of NASA marketing. Promoting movies like The Martian is great, but I wonder if this will backfire in the long run. I agree with my friend Joel Achenbach; Congressional squabbling over NASA’s budget and the lack of a clear vision or plan to get to Mars only serves to contrast what NASA promotes versus what it can actually do.


This is not NASA’s fault, mind you. I lay the blame squarely on Congress. They have a clear path ahead of them—fully funding Commercial Crew—but instead keep throwing money at the Space Launch System (which, if built, will cost so much NASA won’t be able to do anything with it) and the Orion capsule, which now may not be able to take humans in it until 2023, a full eight years after Commercial Crew would’ve been able to send humans into space, had Congress funded it.

What a mess. The majority of Americans love NASA, and it’s incredible that NASA can do such amazing feats like send probes to Pluto and Saturn and protoplanets like Vesta and Ceres at all, let alone given the Keystone Kops feel of the Congress members pulling the purse strings. My only hope now is that these folks in Congress get replaced in the 2016 elections.

It’s hard to look to the stars when the people funding you have their heads jammed into pork barrels.

Tip o’ the spacesuit visor to ruimteaart via astronaut André Kuipers.

Oct. 3 2015 9:30 AM

Crash Course Astronomy: Multiple Star Systems

The stars are not as they seem.

The nearest one is tens of trillions of kilometers away, a distance so terrible that the might and power of Alpha Centauri is reduced to a faint spark that can be washed away by the lights of a nearby city.


Distance shrinks details, too. Alpha Centauri is not one star, but two: one very much like the Sun, though slightly larger, orbiting and orbited by another that is somewhat fainter, cooler, and more orange. There’s also a third star, Proxima Centauri, which orbits the pair but is so faint it can’t be seen by the naked eye even though it is in fact the closest known single star to the solar system.

A large fraction of all the stars in the sky are actually multiple stars—binary, trinaries, or even more complex systems. That alone is enough to want to know more about such multiples; but once you look closer you find that such systems become critically important to our understanding of everything in the Universe.

And, contrary to my usual nature, that’s not an overstatement. Find out why in this week’s episode of Crash Course Astronomy: Binary and Multiple Stars.

I’m excited that this phase of Crash Course is airing: We’re traveling farther out into the Universe, even though we haven’t even left our cosmic backyard yet. But there are larger structures to explore, and grander things yet to see. Just you wait.

Oct. 2 2015 9:15 AM

Behold, the Mess That Is Charon

Charon is so, so weird.

It’s also astonishingly beautiful. Look at it! The image above is a newly released high-resolution color photo of Pluto’s largest moon, taken by the New Horizons spacecraft when it zipped past the Pluto system in July 2015. It’s been enhanced to bring out the color variations more, but this also gives us an idea about the surface features, and how they vary across this strange little world.


There’s so much to see! The most obvious bit is the red splotch at the north pole, informally named Mordor Macula (macula means spot and is commonly used in planetary nomenclature to refer to a big dark region; Mordor is a place you simply don’t walk into).* Pluto is covered in red spots, and it’s thought these are tholins, carbon-based molecules created when ultraviolet sunlight breaks apart molecules, which then reorganize themselves into more complex structures.

Very little of the rest of Charon is red, prompting some scientists to conjecture that Mordor Macula is from some sort of transfer of material from Pluto onto Charon’s surface, possibly from Pluto’s extremely tenuous (but observable) atmosphere. Craters in Mordor are bright, indicating the red material is a veneer; thin enough that small impacts excavate brighter material (likely ices) underneath.

The next most obvious feature is that huge canyon separating the north and south hemispheres. The canyon is staggeringly huge, at least 1,600 kilometers long, making it four times longer than the Grand Canyon and in places far deeper. To scale with Charon, it’s similar to Valles Marineris, the vast canyon scarring the face of Mars.

By the way, the stretch of the canyon just to the right of center, to the right of that centered crater? That’s called Serenity Chasma, and it’s named that way for exactly the reason you think. Shiny.

There’s a big dichotomy between the hemispheres, too. The southern half of Charon has a smoother look—this area is dubbed Vulcan Planum, the Plains of Vulcan—dotted with craters and what looks like cracks or graben (downward thrusted rocks, usually due to faulting as the crust expands). The northern half looks more rugged, less smooth. Perhaps some ancient event caused cryovolcanism—ice volcanoes!—in the southern hemisphere, flooding the plains with ice.

We only have good images of this side of Charon, unfortunately, because the New Horizons mission was a very fast flyby. I’d love to know what the other side looks like in this sort of detail!

A high-res mosaic of part of Charon was also released. It’s well worth your time to peruse the whole thing, but there’s one spot I want to point out:

crater chain
A crater chain dots the surface of Charon.


See that linear feature just above center? That’s a crater chain, usually caused when debris from a big impact is ejected, and then falls back to the ground. But this one is a bit weird; the craters are very close together, almost overlapping, and they don’t seem to point to any other obvious big crater. I’m wondering if this is due to a small body breaking up before it hit, forming a long chain of objects that then hit one after the other along a line. This happened when the comet Shoemaker-Levy 9 hit Jupiter in 1994; Jupiter’s immense gravity ripped the comet into pieces, which hit one after another over several days. Neither Pluto nor Charon has strong gravity, so I’ll admit this seems unlikely. It’s an intriguing formation either way.

As I mentioned, the picture of Charon is enhanced in color to show surface variations. Here’s one more picture, showing what it actually looks like in comparison with Pluto, with both bodies scaled the same way.

Pluto and Charon
The darkness and the light.


Charon is a lot darker than Pluto! That in itself is interesting. Charon most likely formed when an impact on Pluto blew some or most of its crust into space, which went into orbit and coalesced to form Charon (and perhaps the smaller moons, too). It seems to me that they may have started off looking similar, but subsequent events changed them, either brightening Pluto or darkening Charon, or both. Both show evidence of cryovolcanism or more recent resurfacing (the left side of Pluto’s “heart” is likely to be nitrogen ice that’s glacially flowed into lower elevations).

As more images and data trickle back from New Horizons, traveling the long, long emptiness stretching for five billion kilometers, we’ll learn more about the surfaces of these worlds. But every new picture shows something weird and wonderful, and while we get traction on some mysteries, others deepen.

Oh, how I love that! Science is fun.

*Features on Charon are informally named at the moment, but the agreed-upon nomenclature is that they are named after fictional destinations, ships, or voyagers.

Oct. 1 2015 9:30 AM

GOP Presidential Candidates, Science, and Reality

It’s time to not only face facts, but to call them out, too: This cohort of Republican presidential candidates isn’t exactly a brain trust.

Every time I see an article about something one of the GOP contenders has said, I’m stunned at just how much lower they can sink. It’s as if they’re scrambling on purpose to brag about the dumbest possible thing they can come up with.


Think I’m exaggerating? Here are some choice examples of ideas that have come out of the mouth holes of the remaining viable candidates:

None of this stuff is exactly rocket science … but when it comes to climate science, not a single one of these people is even close to planet Earth. They’re in their own alternate reality where up is down and, I suppose literally, hot is cold.

Let’s do a quick rundown of where they all stand:

I’ve been railing against the GOP’s party plank on climate change for years now, so none of this is surprising. But it’s upsetting. I disagree with almost all of the stances of the Republican Party these days, but in the past they at least used to embrace science. Now, though, if one of their candidates says the Sun will rise in the East, I’d lay better odds on the Earth’s rotation having reversed.

This stunning intellectual deficit, whether real or pandering, is wholly the fault of the party itself (and, to an extent, the American public for letting it slide this far). The abject dismissal of reality has become more and more mainstream in the party politicians, and its power soared upward like a hockey stick graph when the Tea Party gained congressional seats in the in 2010 election.

The fallout from this is as fascinating as it is maddening. For example, the Heartland Institute—or as I think of it, the Mos Eisley of think tanks—attacked the pope on his climate change stance, and even a Catholic congress person boycotted the pope’s speech. The internal paradoxes in the minds of these folks must be incredibly turbulent.

More examples can be easily found from other conservative groups. But there’s a glimmer of hope, a glimpse of the path back to reality for the GOP. As the pope showed, religious belief doesn’t necessarily lead to rejecting science; one need only look to outspoken climatologist and Christian evangelist Katharine Hayhoe for that as well. This reveals an underlying aspect of all this that seems to be forgotten: Belief in conservative principles doesn’t lead inevitably to the denial of science.

Conservative political parties in other countries don’t necessarily deny global warming either. It’s only endemic to the GOP. And while funding from the über-far-right Koch brothers clearly affects the way politicians vote in the U.S., not all wealthy donors are the same; Republican businessman Jay Faison has put the incredible sum of $175 million on the table to invest in climate-change–accepting Republican politicians.

The response to that was as predictable as rising temperatures: James “Snow disproves global warming” Inhofe, R-Oklahoma, denounced it. Of course he did; Inhofe is so far removed from reality he actually thinks the pope wasn’t discussing climate change in front of Congress.

I can make a laundry list of problematic GOP planks, but global warming is perhaps the single biggest threat facing humanity today. Faison’s move is a step forward, even if it makes some deniers froth and fume. Their staunch denial may yet lead to political extinction: A majority of Republican voters acknowledge the reality of global warming, and humanity’s role in it. That’s hopeful indeed.

And to those who still deny it, I’ll note that it’s better to take the carrot than the stick: Some people are proposing siccing the RICO Act on corporations actively suppressing global warming and climate change information. This isn’t fringe stuff; an investigation into Exxon revealed they allegedly knew about the threat of global warming for 40 years, yet still funded misinformation campaigns about it. Fossil fuel interests use the same tactics employed by the tobacco industry to downplay harm, and it was the RICO Act that brought those same tobacco companies low.

I’d rather not see things go this far, of course, but that’s the world we now live in: a planet that needs saving from those who would actively burn it down. And that, in sum, accurately describes the current crop of GOP presidential candidates.

Perhaps most sad is that it needn’t be this way. Republicans are supposed to be conservatives. Isn’t it about time they started conserving?

Sept. 30 2015 9:30 AM

Bloom With a View. Two of Them, in Fact.

Oh, I do so love a coincidence. And when it’s about imaging Earth from space, that’s even better.

I subscribe to NASA’s Earth Observatory Image of the Day (and you should, too!), which, oddly enough, posts an image of Earth every day. They’re almost always satellite shots, featuring various amazing portraits of our planet. As a satellite photo nerd I love it, and I learn a lot about Earth every time I see a new one. The cloud images alone are worth it.


One of the most spectacular and lovely kinds of photos they post are of phytoplankton blooms—huge bursts of growth (usually of cyanobacteria) in the ocean. Warmer waters can create conditions where nutrients and sunlight become abundant to the little plants, and they go forth and multiply. Blooms can be huge, hundreds of kilometers across.

The image above shows (a small part of) a bloom in the Baltic Sea, just north of Poland. It was taken by Landsat 8 on Aug. 11, and it’s not “true color,” that is, what your eye would see. The detectors used are sensitive to colors across a range of the spectrum, so the colors displayed are close to red, green, and blue, but there’s quite a bit of overlap (for example, the detector that sees in the green is also sensitive to yellow, and the blue one sees green as well). Still, the bloom is eerily beautiful. You can see airplane contrails and the wakes of ships in the original full-res image, too.

The spiral pattern is lovely, caused by eddies in the sea currents. Cyanobacteria are plants (more or less) so they flow along with the water.

The coincidence? The European Space Agency released a similar picture taken just a few days before, on Aug. 7, using the Sentinel-2 Earth-observing satellite:

Sentinel bloom
If you told me this was a radio map of a spiral galaxy, I might believe you.

Photo by Copernicus Sentinel data (2015)/ESA

Whoa. I’m not positive that’s the same swirl, but it’s from the same general area of the Baltic Sea (the Sentinel image is also part of a much larger image). Interestingly, both images from Landsat and Sentinel-2 show ships crossing their respective swirl; in each you can see the ship as a dot followed by a black trail.

Cyanobacterial blooms are important to study. They can rob water of oxygen and nutrients, and some phytoplanktons produce toxins that can be dangerous. And here we have two space agencies studying the same bloom at two different times with two different satellites! It’s really gratifying to see nations taking this sort of work seriously … especially when one faction of my own nation doesn’t.

We need to understand our planet as best we can. Not just because doing so produces such wonderful natural art, but because we are part of Nature ourselves, and we influence it just as it influences us. Understanding it is critical.

After all, Nature can live without us, but we can’t live without Nature.

Sept. 29 2015 9:30 AM

Global Epic Eclipse

Well, despite some baseless fears, we’re still here after Sunday night’s lovely lunar eclipse.

It was quite nice here in Colorado; the Moon was still very low to the horizon when it started to pass into the darkest part of the Earth’s shadow. I was just finished setting up my Celestron Regal M2 80ED spotting ’scope to watch when I saw an airplane approaching the rising Moon … and as I shot the video, to my surprise I got two planes transiting!


That was fun. The Moon was still yellowish as it rose due to atmospheric effects. It was just about the enter the darker part of the Earth’s shadow (called the umbra) but even then you can see the left side is darker and redder than the right.

I also did a live Periscope as the Moon darkened, winding up with more than 8,000 people watching at different points. I love seeing so many folks interested in what’s going on in the sky!

I think my video is pretty cool, but master astrophotographer Thierry Legault did me one better. Well, more than one: He caught the International Space Station transiting the Moon during the eclipse!

That is so cool. He told me that, to the best of his knowledge, this is the first time anyone has caught the ISS transiting the Moon during a lunar eclipse on video.

I want to share a couple of photos, too. As the sky darkened, the eclipsed Moon rose through several thin cloud banks, and I liked the feel of this one:

eclipse clouds

Photo by Phil Plait

You can see the eclipsed part of the Moon on the left. It helps sometimes to have something else in the field of view when you’re taking pictures like this. A cloud is nice, but sometimes something more recognizable can turn a nice shot into a fantastic one.

Like, say, this:

Eclipse and monument
Oh say can you see the eclipse?

Photo by NASA/Aubrey Gemignani

Wow. Yeah, sometimes it’s all about the framing.

If you want to learn more about these events, I talk all about them in my Crash Course Astronomy episode on eclipses. The next lunar eclipse visible to the U.S. won’t be until 2018, but August 2017 will bring the Great American Solar Eclipse. Stay tuned for more on that.

Sept. 28 2015 12:27 PM

The Big Mars News: Flowing Water on Mars, at Least Briefly

Scientists have found what they think is evidence of extant, if brief, flowing water on Mars.

In a NASA press conference on Monday, scientists claimed that images and spectra taken by the Mars Reconnaissance Orbiter’s HiRISE camera show what are called Recurrent Slope Lineae, or RSLs, straight dark streaks that run down the sides of craters and canyons on Mars. These features, which are a few meters across and hundreds of meters long, change with the seasons, becoming darker and more obvious in the spring and summer on the sides of crater walls facing the Sun. That strongly implies that warmth triggers the formation of the RSLs. The important finding: Scientists found evidence of salt deposits in these features, which in turn implies that briny, salty water is the force behind them. They think the darkening seen every spring is from water seepage!


If you want details, I wrote all about this Sunday in an article based on papers written by the scientists in question to be presented at a planetary science conference in Europe. I had not read the (embargoed) science papers, so what I wrote was based solely on those public papers, but it looks like I was right on the money.

Mind you, the detection of water here is indirect, through the dark streaks and the presence of salt. Still, the evidence they presented is very compelling, and their conclusions, in my opinion, likely to be correct. But there’s a problem, and it’s a big one: Where does the water come from?

We know there’s ice under the Martian surface. We see lots of evidence for it—it was seen directly by the Phoenix lander in 2008, and small asteroid impacts leave craters behind that excavate ice that can be seen. But Phoenix landed at high latitude, near the north pole where you’d expect ice, and the craters with ice only reach as far as midlatitude. But these RSLs are seen closer to the equator of Mars. Over time, the water ice there, to at least mild depths, should have disappeared, melting away.

Because of this, the authors of the work speculate that perhaps water is absorbed into the ground from the atmosphere, where it collects until there’s enough for it to flow—a process with the lovely name of deliquescence. The soil of Mars is loaded with a chemical called perchlorate, which is capable of absorbing water in this way, and perchlorates were found at the RSL sites.

So this idea ... holds water.

Still, the air on Mars is exceedingly thin, less than 1 percent of Earth’s. And there’s not much water in it, either, so it’s difficult to understand how enough water could collect to form these seepages. Although deliquescence is the preferred scenario by the scientists involved, they also admit the actual source of the water is still something of a mystery.

Opinion time: This is a wonderful discovery, and an important one. The origin of these features has been a mystery for a long time, and it does look like we’re finally starting to get a grip on it.

But it’s far from solved. Where does the water come from? How much is there? Is it just water, or are there other substances involved?

And what does this mean for the possibility for life on Mars? Well, in my opinion, it doesn’t change much. Not yet. We know Mars has lots of water ice, and it once had vast amounts of standing and flowing liquid water on its surface in the past. This doesn’t change that. Mars may once have had life, but we still don’t know, and don’t know if there’s life there now.

What it does change is the idea that there could be liquid water beneath the surface of Mars. This makes it less unlikely, I’d say, which I know sounds weak. But what we’ve seen here is temporary flowing water, not persistent liquid water. The bottom line is that we still don’t know if liquid water exists under the Martian surface or not.

But we’re learning. This is just one of many steps we’re taking in observing Mars. Remember, Mars is a planet, an entire world, with a rich history, diverse geography, and a lot of real estate. We’ve only just scratched the surface—in this case, almost literally—and there are great depths left to explore.