Bad Astronomy Blog
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.
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.
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.
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.
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?
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 they 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 Congresspeople 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.
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 stars, 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 back yard yet. But there are larger structures to explore, and grander things yet to see. Just you wait.
Charon is so, so weird.
It’s also astonishingly beautiful. Look at it! The image above is a newly released high-resolution color 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 1600 km 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:
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.
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.
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:
- Donald Trump—whose campaign, I’m increasingly thinking, is simply an elaborate performance art piece to amplify his brand and who, it needs to be remembered, has been the front-runner for months now—has said so many forehead-slappingly dumbosities that picking any is like trying to choose a specific drop of water from the ocean. But two obvious ones are his tax plan that would almost literally destroy our government and his idea to build a border wall that is literally impossible to build.
- Carly Fiorina tells outrageous lies, repeats them over and again, and thinks no one will check her on them. Too bad for her there are experts willing to speak up.
- Ted Cruz wants to shut down the government based on the subject of those lies. Remember, Planned Parenthood doesn't get federal money for abortions (except under extremely limited circumstances like the imperiled health of the mother), making this whole thing a political and theatrical farce.
- Marco Rubio is uncertain about things he should’ve learned in eighth grade science, and when confronted on this claims he’s not a scientist. That’s like saying you don’t know where Washington, D.C., is on a map because you’re not a cartographer.
- Jeb Bush apparently openly mocks smart people, saying, “When I am elected president, the political hacks and the academics are going to take the back seat.” Yes, heaven forbid we let people like academics who have spent their lives studying a problem actually have a say in the solution.
- As for Ben Carson … well, there’s this.
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:
- Donald Trump thinks climate change is some sort of China-manufactured hoax. By the way, if you look up irony in the dictionary there’s a picture of Trump.
- Carly Fiorina wants to play both sides as well, saying global warming is real (but there’s nothing we can do about it) but by the way global warming isn’t real.
- Ted Cruz thinks climatologists are flat-Earthers and that he himself is Galileo. I think he was confusing Galileo with George Orwell.
- Marco Rubio simply parrots long-debunked denier nonsense.
- Not to be out-ironied by Trump and Rubio, Jeb Bush was unhappy about Pope Francis saying we need to take action on climate change. Bush said we should ignore the pope because he’s not a scientist. Actually, he is. And while the problems I have with this pope are legion, in this particular case he’s right.
- As for Ben Carson, well. He says climate change is irrelevant. Irrelevant. So there’s that.
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?
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 planets, 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:
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.
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 over 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:
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:
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 US won’t be until 2018, but August 2017 will bring the Great American Solar Eclipse. Stay tuned for more on that.
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.
By now, many of you have heard about some big announcement NASA is about to make about Mars. The news is embargoed until the press conference Monday (which you can watch live at 11:30 EDT), but of course speculation is rampant, especially since the press release says it’s a “major science finding”.
In the email NASA sent out, the names of some panelists were given: Alfred McEwen, Lujendra Ojha, and Mary Beth Wilhelm. McEwen is the Principal Investigator for the wonderful HiRISE camera on the Mars Reconnaissance Orbiter. Ojha studies recurrent features on Mars that look very much like they were carved from water, like gullies down the sides of craters. Wilhelm studies many things, including the habitability of ancient Martian terrain.
As many people have pointed out on social media, at a European planetary science conference on Monday, McEwen and Ojha are presenting results of a study showing that seepage in crater walls appears to be seasonal, and most likely due to water. Not only that, but Ojha and Wilhelm are presenting results that show the presence of salts in crater wall gullies, too, implying strongly they are due to water leakage.
I’m posting this now to hopefully extinguish rampant speculation (what I write here is based on evidence, so call it mild speculation). I assume these new results will be a major part of the news conference, but there might be more as well.
I also wanted to give a little bit of background on these gullies, since they’re pretty cool. As far back as 2007, NASA announced they might be from water, though a year later a study was released indicating many might be better explained as dry grains flowing downhill. In 2010 more gullies popped up that looked like they could be from liquid flowing, but the evidence was still a bit circumstantial. We know water once flowed on Mars, a long time ago, and there’s plenty of evidence for ancient standing lakes and even oceans. Also, even now there’s lots of water ice just below the surface across a wide range of latitudes, too.
Salty water melts at lower temperatures than fresh water, so if that’s what lurks behind crater walls, then in the spring sunlight can warm the ground and cause seepage. The results being presented at the European conference question the idea of water ice under the surface being the cause, and suggest it may be from deliquescence; absorption from the atmosphere in the ground until the water can break through. That seems unlikely, but we’ll get more info during the press conference.
Mind you, as of right now we have never seen any evidence for the presence of extant liquid water on Mars. Even the temporary existence of water in a liquid state is scientifically interesting, even exciting. However, it’s also been found that a type of chemical called perchlorates is widespread in Martian soil, which makes the hunt for life a bit more of a problem. I expect that will come up in the press conference as well.
I’ll be listening in and will write up the news as soon as I can. Stay Tuned.
In the meantime, because why not, here’s my Crash Course Astronomy episode on Mars. Enjoy!
I love posting pictures of the Earth from space. It’s fun to see things from a height, and get an overview of our planet. Volcanoes, lakes, deserts, cyanobacterial blooms … sometimes you need to take a step back (well, up) to see things for how they are.
But then you get a picture of some place you recognize, and suddenly it becomes personal.
To wit: On April 29 an astronaut on the International Space Station took a picture of me.
Can you see me? I’m in there. This photo shows a healthy chunk of west-central Colorado, where the midwestern plains meet the Rocky Mountains (north is more or less to the right). The big city on the left is Denver, and to the right, sitting right on the border between flat and steep, is Boulder. There’s a road extending almost straight down from Boulder (or in real directions, to the northeast) called 119, or Diagonal Highway. The city at the bottom is Longmont, and in between the two is the small town of Niwot. The Earth Observatory Picture of the Day, where I got this photo, also has an annotated map.
I’ve ridden my bike all through that part of this picture, and it’s a bit surreal to see it this way. The reservoir, smaller lakes, farmland … I’ve seen a lot of it from eye height, but not 400 kilometer high!
People think Denver is in the mountains, but it’s really quite a bit into the plains. Boulder sits right where the mountains pop up, which is one of many reasons it’s such an amazing place to live. The view is spectacular.
This picture lays it out so well! And I checked my calendar: On April 29 I was at home, which means I’m in this picture. So are roughly 3 million other people; most of the population of Colorado is in this picture.
Maybe you are too. Well, the odds are low unless you live near me. But a lot of the planet has been photographed this way, and those pictures are online. Go take a look! Maybe you can find a shot of your hometown.
And next time the space station is overhead, maybe they’re taking another one. Don’t forget to wave!
OK, so here’s the thing about black holes: They’re weird.
Well, that’s not the only thing about black holes. And that’s the problem. There’s a lot to know about black holes, and it goes from simple to brain-melty pretty quickly. I had big plans for the Crash Course Astronomy episode about black holes, covering so many of the cool things about them.
After writing more than 3,000 words on them—the equivalent of about 25 minutes of footage—I realized I had a problem. A lot of stuff had to go. So I went through and cut this, excised that. What was left is, I hope, a pretty good primer on black holes, with the info you need to understand the basics.
The good news? Most of the stuff I cut will show up in later episodes. I’m pretty good about recycling electrons. If you’re impatient and want to know more about them now, then try these articles:
- Ten Things You Don’t Know About Black Holes
- Why Do Black Holes Have Such Strong Gravity?
- Weighing a Galactic Monster
- Let Me Hold You in My Anomalous Arms
- Sputtering Black Hole Caught by Hubble
- What Kind of Object Can Survive a Close Encounter With a Monster Black Hole?
- A Supermassive Black Hole’s Fiery and Furious Wind
- Follow-Up: Interstellar Mea Culpa (I made a boo-boo about black holes)
- Superfast Spinning Black Hole Tearing Up Space at Nearly the Speed of Light
- How Do You Weigh a Supermassive Black Hole?
- … or you could just search my blog for “black holes.” And stay tuned, because they'll turn up many more times in future episodes!
Oh, one more thing: In the video, at about the 8:30 mark, I talk about the perception of time near an object with gravity, and how it slows down. I say that someone near a black hole perceives time as moving more slowly than someone far away does. I should have phrased that differently; both people observe time to flow normally. To them. But they see each other's time flow rate change. Someone far away from the black hole sees the time flowing more slowly for the person near the black hole while the person close to the black hole sees the person's time far away flow more quickly. Time is relative; grammar isn't. I should've been more clear.
I was going to write a big flowery introduction to preface this new image of Pluto from the New Horizons spacecraft, but screw that.
Just look at it. Seriously. Look.
That ridiculously gorgeous picture is actually a combination of three images shot by New Horizons, one each using a blue, red, and near-infrared filter. So this isn’t what you’d see with your own eyes if you flew past Pluto (and weren’t dead from hypothermic anoxia), but it’s still simply amazing. By the way, this is a very, very ensmallened version of the picture; click it to get a 2000 x 2000 pixel version.
Or, you could grab the 8000 x 8000 pixel shot. Y'know. If you want.
As usual, Emily Lakdawalla does a great job explaining all this. In a nutshell, it was taken by the Multi-spectral Visible Imaging Camera. It has several detectors on it, three of which are dedicated to seeing blue, red, and infrared. They use what’s called the “pushbroom” technique to take images, basically sweeping across an object like a scanner does when you scan a document. It’s a commonly used technique for spacecraft, so you don’t have to build a huge detector.
What can you say about this shot, though? Pluto is gorgeous! You can see the heart-shaped Sputnik Planum feature in the middle, and some terrain on the left that’s highly reflective in infrared (colored red in the photo). Those highlands are pocked with craters, in contrast to Sputnik, which is smooth — that’s an indicator of relative age; smooth terrain has probably been resurfaced, and so it’s younger.
I’m pretty interested in the higher surface features you can see that define the left side of the heart. What could cause such tall mountains so close to lower terrain?
And check out this close up of a region near the leftmost part of the heart:
Whoa. Mountains pop up higher than the nitrogen ice plain below… which isn’t as smooth as I first thought. It appears almost corrugated, like it’s stippled with dunes. There’s no word yet on what’s actually causing that; the ice might be sublimating (turning directly into a gas) which could cause a rippling effect.
Again, Emily has more close-ups and discussion, care of Alex Parker, the astronomer who created this jaw-dropping image. NASA has a few more detailed shots as well, including the highest-resolution map ever made of the surface of Pluto.
Remember, too, that new raw images are released every week on the New Horizons website. You should check there to see what’s hot off the interplanetary presses; it’ll take the better part of a year to get all the data back from the spacecraft. These marvels are just the beginning. It’s a whole new world out there on the edge of the main solar system. A lot more wonder awaits.
At one point in time, GOP presidential candidate Ben Carson may have been best known as an excellent, even groundbreaking, neurosurgeon. In recent years, though, he’s done everything he can to throw that reputation away.
It won’t surprise regular readers to know I disagree with him on, well, almost everything. But recently he’s starting to get more heat about his religious views. He’s an outspoken creationist.
This actually goes way back. In 2006 he clearly stated his anti-evolutionary views and has repeated these claims many times since. In 2012 there was controversy over this when he was asked to give the commencement address at Emory University. In 2004 he said that people who accept evolution “dismiss ethics,” a comment he later backed down on a very tiny little bit (later saying they “might have more difficulty deriving where their ethics come from”).
I’d heard about all this before, but an article at BuzzFeed has something I hadn’t heard: In 2012, in a speech at an event called “Celebration of Creation,” he said that Darwin came up with evolutionary theory because the devil made him do it.
I mean that literally. He said, “I personally believe that this theory that Darwin came up with was something that was encouraged by the adversary.” The Adversary is a nickname for the devil; it’s the actual translation of the word “Satan.” So there’s that.
He also dismissed the Big Bang, calling it a “fairy tale.” The irony of this is palpable. When recently called on this claim, he dug in, saying (about people who think the Big Bang is true), “Here’s the key, I then say to them look, ‘I’m not gonna criticize you, you have a lot more faith then I have.’ I couldn’t, I don’t have enough faith to believe that.”
Wow. Where to start?
OK, how about this: The Big Bang is not something you believe in. It’s a scientific model, supported by a truly vast amount of evidence. It doesn’t take faith, it takes science (and, despite Carson’s claims, science is not faith-based).
Creationists who dismiss the Big Bang usually do so because they think the Earth is young, 6,000–10,000 years old. This belief is, to put it simply, wrong. We know the Earth is more than 4.5 billion years old, give or take a few million years. The evidence for this is overwhelming.
We also know the Universe itself is old; a huge number of independent lines of evidence make this clear. It doesn’t take faith to think the Big Bang is true, it takes a profound dismissal of all of science to think it isn’t.
Which brings us to evolution. Young Earth Creationists dismiss this as well due to the age issues, as well as others (for example, the Bible stating that God created Adam fully formed and in his image).
It bothers me greatly when a presidential candidate is so cavalier in dismissing facts. That’s a route we’ve been down before, and it leads to Very Bad Things.
As for Carson’s statement on ethics, well, humans were ethical long before monotheism came around. His claim that people who accept evolution is true might have difficulty with ethics is profoundly insulting to scientists.
The almost unutterable irony here is how Carson dismisses this all, talking about “high-faluting” scientists. But he was a neurosurgeon. His entire career owes its existence to science, yet he tosses out the men and women over the past few centuries whose expertise allowed him to benefit so greatly from his practice.
I know a lot of the Republican base is very religious, and they have every right to be. But fundamentalism is dangerous; it promotes clearly erroneous claims while simultaneously encouraging people to legislate those beliefs. We’ve seen what happens there; fittingly enough due to the antics of Bobby Jindal, another GOP presidential candidate. It shortchanges our children out of an education they’ll need to survive in our science- and technology-based society.
I also know that the vast majority of creationists have very basic misunderstandings about evolution, the Big Bang, and science in general; I addressed this in depth when I wrote my article “Answers for Creationists.” I tried very hard to be polite in that post, given I was dealing on a personal level with people’s personal beliefs.
I take a different stance when it’s a politician who espouses these views, especially when he’s running for the highest office in America. If someone wants to run this country, then he better show that he has a solid grasp on reality. Dismissing and actively denigrating strongly understood science—whether it’s astronomy, biology, or climatology—is at the very least cause to dump him.
On Sept. 27 and 28, the Moon will enter Earth’s shadow, creating a total lunar eclipse. These only happen a couple of times a year, and are a great event to watch.
First, the quick stuff you need: The Moon begins to enter the dark part of Earth’s shadow starting at 01:07 UTC on Sunday night/Monday morning. To be clear, for folks in the U.S. that’s Sunday night, starting at 9:07 p.m. Eastern time; for most of the country the Moon will be low to the eastern horizon. At that time you’ll start to see a dark “bite” taken out of the Moon on the part of it nearest the horizon (the lower left, again for Americans).
It’ll take just over an hour for the Moon to pass fully into the shadow, and the last sliver of it will slip into darkness at 02:11 UTC (10:11 Eastern). It’ll stay dark for more than an hour, and then start to be illuminated once again at 03:23 UTC (11:23 Eastern). “Last contact,” when it is out of Earth’s shadow, occurs at 04:27 UTC (00:27 Eastern, after midnight).
People in the western U.S. (west of Colorado) will see the Moon already in eclipse when it rises. Here’s a map to show if you’ll be able to view the eclipse:
“U1” is when the Moon begins to enter the dark part of the shadow (the umbra), so everyone east of that spot in the U.S. will see the whole eclipse. Everyone west of the line marked “U4” (when the last part of the Moon leaves the shadow) will miss the event. Sorry. We live on an opaque spinning planet, so someone always misses out. Anyway, the diagram below shows the Moon's path through the Earth's shadow.
You don’t need any special equipment to see this; just go outside and look at the Moon. (This is different than a solar eclipse, where you need eye protection from the bright Sun.) Having said that, I’ve always found binoculars to be best aid to viewing. The Moon can take on an odd three-dimensional appearance when you use binoculars during an eclipse, and it’s pretty cool to see. A telescope is great, too, if you have access to one. If there’s a local astronomy club or observatory near you, see if they’re running a star party for it.
I’ve written before about exactly how and why we get lunar eclipses; the dance of the Moon, Earth, and Sun has to play out just right for the Moon to move through Earth’s shadow in the sky. Go there to get details, but there’s one thing I want to emphasize.
When the Moon is fully eclipsed it usually turns red, though sometimes the effect is more subtle than other times. This is because from the Moon’s point of view the Earth is blocking the Sun, and sunlight gets filtered through the thin layer of Earth’s atmosphere, reddening it. If you were standing on the Moon, it’s like you’re seeing every sunrise and sunset on Earth all at once!
How about that?
You can read more about the eclipse at the Time and Date site, EarthSky (which separately lists the timing for the eclipse in different U.S. local time zones), and Wikipedia. Also, the Virtual Observatory will be running a live viewing of the event online, in case your weather isn’t cooperative. So will my friend Adam Block at the Mt. Lemmon SkyCenter.
Also, I just so happen to have done an entire episode of Crash Course Astronomy on eclipses. Watch!
I’ll note that this eclipse happens very close to when the Moon is at perigee, the part of its elliptical orbit when it’s closest to Earth. Its average distance from Earth (center to center) is about 384,000 kilometers, and during the eclipse it’ll be only 356,900 km distant, 7 percent closer than average. That means it’ll look 7 percent wider than average … but I doubt you’ll notice. If you took a picture when it’s at apogee (farthest from Earth) on Sept. 14—when it’s 406,500 km away—and then compared it with a picture taken on Sept. 28 you’d definitely see the difference! But just going out and looking during the eclipse you’re unlikely to be able to tell.
Of course, the Moon will be rising for many people in the U.S. at the start of the eclipse, so the Moon may look huge due to the well-known Moon Illusion. But don’t be fooled! A lot of websites will no doubt be hyping up the “Supermoon” (a full Moon at or near perigee), but don’t be taken in by them. The difference in size isn’t all that much.
Not to pooh-pooh any of this! Lunar eclipses are fun; they play out relatively slowly, so you can take a look, go inside for a few minutes, then go back outside to see more of the Moon gone. It’s a great opportunity to try your photography skills, and because you don’t need any equipment, it’s nice to get friends and family together outside to take a peek.
I strongly recommend marking your calendar. The next total lunar eclipse won’t happen until January 2018! So watch this one if you can.
A weird animated graphic depicting a distorted, lumpy Earth has gone viral over the ‘net in the past few days, claiming that this is what the Earth looks like “without water”.
There’s only one problem with it: Nope. Nopity nope nope nope.
That’s not at all what it shows. What it actually depicts is the Earth’s geoid: a way of describing Earth’s gravitational field. The original graphic is a product of the MATLAB package described by Aleš Bezděk (credits at that link). Here it is in all its knobby goodness:
Earth’s gravity isn’t smooth at the surface, but is stronger in some places than others. That’s because the Earth isn’t a perfectly homogeneous sphere (that is, the exact same density throughout its interior), but has some places where it’s more dense and places where it’s less dense. That affects the surface gravity.
When you stand on the surface of the Earth, it feels like gravity is pulling you down to the center. But if you stand next to a denser region, its gravity pulls you a little bit to the side, away from the center. The geoid in the viral graphic shows this; in that map gravity always pulls you perpendicular to the surface depicted.
I know that sounds weird, but basically it’s saying that if you’re on the side of a “hill” shown in the geoid graphic, a plumb bob (a heavy weight tied to a string) will not point toward the center of the Earth, but perpendicular to the surface where you’re standing. The actual graphic is hugely exaggerated on purpose, making it easier to see the Earth’s lumpy gravity field.
I have to laugh (if somewhat ruefully). One thing I find whenever some wrong science factoid goes viral is that it’s usually exactly wrong; it states the opposite of what’s actually going on. That’s true here! How?
Another way to describe the geoid is that it’s the shape of an object if it’s perfectly fluid; if the surface is allowed to flow freely.
For a perfectly homogeneous object (say a big non-rotating drop of water in space) the geoid would be a sphere. For the Earth, well, it’s what’s shown in the graphic. In other words, that graphic doesn’t show the Earth without water, it shows what the shape of the Earth’s surface would look like if the surface were entirely covered in water.
See? Exactly wrong.
It’s easy, given the caption, to think that this is what the Earth’s solid surface under the oceans looks like. But look at the scale bar in the graphic; it goes from about +80 meters to -80 meters. That’s a teeny tiny fraction of Earth’s size. In physical reality, even if the Earth were covered in water it wouldn’t be anywhere near as lumpy as depicted. Again, it’s exaggerated for clarity.
Think about this, too: The deepest part of the Earth’s ocean (the Mariana Trench) is about 10 km deep. The Earth is nearly 13,000 km across! Take away all the water from the Earth’s surface and you’d hardly notice; the elevation difference between the highest mountain and lowest point in the ocean is less than 20 km, about a tenth of a percent of the Earth’s diameter.
And yes, that drop is the size of the sphere you’d get if you extracted all the Earth’s ocean water (as well as atmospheric water vapor, lakes, ice caps, and so on). It’s not much compared to the whole planet, is it?
The lesson here? Beware of factoids without evidence to back them up. Also beware of science factoids presented by non-science sites. Heck, beware of them even from science sites; we make mistakes sometimes.
But be super duper skeptical of stuff on the ‘net given without attribution, too. That usually means it’s been through at least one layer added by someone who doesn’t necessarily understand what they’re writing. It could even be something just made up out of thin air.
And that usually means… it doesn’t hold water.
Note: I think this was originally posted to Twitter by 9GAGGifs, a site where people can upload images without any attribution, practically guaranteeing stuff that abuses science can go viral with virtually no fact-checking (I’ll note I don’t have anything against such sites in theory, but in practice a lot of stuff is posted without attribution which, not to put too fine a point on it, sucks). It was then picked up by DesignTimes, a Twitter feed that, upon my inspection, also appears to commonly post stuff without attribution (or, in this case, fact-checking).
We live in the Milky Way, a gigantic galactic disk of stars, gas, and dust. Our galaxy also has several smaller companion galaxies, mostly elliptical and irregular dwarf galaxies. One of them is called the Large Magellanic Cloud, about 160,000 light-years away. It’s fairly irregular, though recent studies have shown it may have used to be a small barred spiral galaxy.
I have studied a bit of this galaxy (it was the host of a star that blew up in 1987 which was the subject of my Ph.D. work), but it still manages to surprise me. I didn’t know, for example, that is was the host of a few globular clusters. These are dense balls of stars, sometimes contains up to a million, all orbiting each other in a spherical knot.
One of these globulars near the LMC (as those of us in the know call it) is NGC 1783, a spectacular example of such a beast. How spectacular?
Very pretty! In this Hubble image you can see how the core is tightly packed with stars, and they spread out with distance. I’ve always thought they look like Technicolor beehives.
The colors of the stars are important: They reveal the ages of these clusters. High mass stars are bluer, and tend to blow up while young. Over time, the stars in the cluster that survive are the lower mass ones, which are redder. By examining the colors of the clusters stars we can determine the age. Most globulars are ancient, more than 10 billion years old.
NGC 1783 is again a surprise: Studies of its age show it to be very young, only about 1.4 billion years old! That means the LMC has been capable of making globular clusters far more recently than the Milky Way has.
In fact, it may yet still be making them. The Tarantula Nebula is a huge and magnificent gas cloud in the LMC, a stellar nursery churning out thousands of stars. Recent observations indicate that the cluster of stars being formed there are well on their way to becoming a globular!
My my. The LMC is full of surprises. I think it’s compelling that the few dwarf galaxies close enough to study seem to be so complex. Small doesn’t mean uninteresting, especially when it comes to astronomical objects.
A microburst might sound like some astronomical minicatastrophe, but it’s actually a much more terrestrial event: A sudden accelerating downdraft of wind from a cloud that can, at times, be quite violent.
Some are dry, with just air descending at high speed, while some are wet, loaded with water. Photographer Bryan Snider caught the latter when he was taking time-lapse footage of a thunderstorm over Tucson, Arizona, on Aug. 8:
You can see the rain falling, then at about 00:11 you can see the microburst develop and drop. A second one happens just moments later, too. It’s fascinating to see it hit the ground and blow outwards in a circle. The position of the Sun was perfect to illuminate just the bottom of the event. (Note: After I wrote this, but before it went live, I found that a webcam at Kitt Peak National Observatory caught the same microburst.)
This one didn’t look too violent, despite the scale. But microbursts can be; one that let loose in Montana in 1998 knocked down trees like they were twigs. Even less powerful ones can be a danger to aircraft, and they’re difficult to predict.
I’ve never seen an actual microburst, though I did once see a series of downdrafts from clouds forming beautiful fingers as they descended, one after another in a row. It was mesmerizing, and interestingly enough I asked some meteorologists to help me identify them, but we came up empty.
It’s not unusual for astronomers to be interested in meteorology, and meteorologists to be interested in astronomy. After all, we both look up for a living, and there’s always something amazing waiting to be seen in the sky.
Tip o' the umbrella to Henry NL.
Sometimes, I just wanna post a cool picture. Like now.
Whoa. That photo was taken in June 2013, when a lightning storm raged over Cerro Paranal in Chile. See those four bumps on the top of that hill? Those are the enclosures of the four sub-units of the Very Large Telescope, each an 8-meter behemoth. A person standing there would be too small to see in this photo.
But what I really love about this—besides the obvious drama—is over on the left. That patch of clear sky reveals a star barely visible over the mountains’s flank: Procyon, the 8th brightest star in the sky. It’s a relatively old star, a couple of billion years of age, and is actually a binary: a massive, hot star orbited by a small white dwarf, the exhausted core of a star long dead. They’re separated by a couple of billion kilometers, but from our distance of more than 100 trillion kilometers, they appear as a single star by eye.
It’s a reminder to me that there can be much sound and fury, but it’s amplified by being nearby; from a great distance much larger fury can be subdued into a flickering dot.
Despite my fascination with asteroid impacts, black holes, supernovae, and other über-violent astronomical catastrophes, they don’t scare me.
I mean, sure, they’re scary, but they don’t frighten me personally, viscerally. The wonder and awe I feel from them is real, but I don’t get that holy-yikes-these-things-can-kill-us vibe. They’re just too far away.
Then there are magnetars.
These are freshly minted neutron stars, the collapsed cores of high-mass that have exploded, leaving behind the ridiculously dense, rapidly spinning, fiercely magnetized ball of neutrons.
In 2004, one of these beasts halfway across the galaxy decided to throw a tantrum, and its effects were physically felt on Earth. From 50,000 light years away.
So they give me the heebie-jeebies. Just a little.
So how do magnetars get their power? How does a neutron star form in the first place? And how do pulsars play into this?
Here’s a thought: Watch this week’s Crash Course Astronomy!
It’s funny how quantum mechanics — the physics of the very very small — plays such a huge role in astronomy, which generally deals with things that are very very big. The Universe doesn’t discriminate against size, and in fact size itself can play a massive role in how objects form and how the behave.
Like with black holes… but I get ahead of myself.