Bad Astronomy
The entire universe in blog form

July 3 2015 7:00 AM

Crash Course Astronomy: Meteors!

I’m not gonna lie to you: This is one of my favorite episodes of Crash Course Astronomy we’ve done so far. It was a lot of fun, and this is just such a fantastic topic to talk about. So here you go: “Meteors, Meteoroids, and Meteorites, Oh My!”

Those meteorites I held up in the intro are mine; they’re examples of Sikhote Alin, an iron meteorite that rained debris over Russia in 1947. They’re my favorite; they come in all sorts of exotic and bizarre shapes, and their color is gunmetal blue-black. They’re a bit pricey, but you can buy them for yourself. I suggest perusing the store of my friend Geoff Notkin (you may have seen him on the Discovery Channel’s “Meteorite Men” TV show). He has great samples.


I’ve written about meteors about seventy-four bazillion times. If you’re looking for a generic meteor shower viewing guide, I’ve written them for several showers. Here’s one from the 2014 Geminids. I’ve written about the Russian Chelyabinsk impact several times, including the night it hit, a followup a year later featuring what we’ve learned, a cool video where you can see a small chunk hitting a frozen lake, and another video where they hauled a big chunk out of a lake.

I also wrote about the Perseid astronaut Ron Garan saw from the space station… including a calculation for how often the space station gets hit by a meteor on average.

You can see why I had so much fun making this episode. I’m endlessly fascinated by meteors, and hopefully, now, you are too. 

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July 2 2015 2:52 PM

Washington State Woman Is First Measles Death in U.S. in 12 Years

In Clallam County, Washington, a woman has died of complications from measles. This is the first U.S. death from measles since 2003.

Clallam County had an outbreak of measles earlier this year, when five people were diagnosed with the disease. The woman who died brings this to a total of six.


She likely contracted measles when she visited a health facility; a person who was later identified as having measles was there at the same time. The woman who died was apparently taking a series of medications that lowered her immune system’s ability to fight off disease. Although she didn’t present a rash or other obvious external symptoms, she died of pneumonia caused by the measles infection.

Vaccination rates in that area of Washington are lower than they should be. We—and I do mean “we”—need the public to have as high a rate of vaccination as possible, to ensure herd immunity, so that the bacteria and viruses that can cause such illness and death have as few places to hide as we can muster. When rates drop, we get outbreaks, like the one in Disneyland that sickened so many and spread the highly contagious disease to many parts of the country.

One person who came down with measles in the Clallam outbreak had been inoculated, but it was decades ago, when the shot was less effective. It’s important to make sure your immunizations are up-to-date.

This death comes on the heels of California making it harder for parents to opt out of vaccinating their school-age children; only a medical exemption will be accepted (before, they also allowed religious and personal reasons). I’m very happy this law passed. I’ll note that Washington state, where the woman died, still allows personal exemptions. Hopefully their legislature will rethink that policy.

It also comes right after a huge and awful backlash against the new California law by the anti-vax crowd, including actor Jim Carrey, who tweeted a series of foolish and blatantly incorrect statements about vaccines. He brought up the zombie ideas of mercury poisoning (a non-issue) and conspiratorial Big Pharma nonsense.

Let me be very, very clear: Anti-vax rhetoric like that makes people scared to get vaccinated. Rates drop, herd immunity drops, outbreaks occur, and people get sick. Some die. This is a direct, step-by-step chain.

No one is forcing you to get vaccinated. If you want your children to attend school in California, then yes, you have to get hem vaccinated unless there’s a pressing medical reason. But no one is coming to your door, holding you down, and injecting you with anything. You still have a choice. That choice boils down to this: If you want to rely on public services, then you have to support those services. One method of support is making sure you have minimized the risk of your child giving other children dangerous infectious diseases.

And it’s not just children. It’s elderly people who are at risk, too, and people—like the woman who died in Washington—who are immunocompromised. I have family members in both these categories, which is why my entire family is up-to-date on our vaccinations.

When you get vaccinated, you are helping not just yourself, but also many, many people around you of all ages. Read up about measles, and what you need to do. Ask your board-certified doctor and see if you need to be vaccinated (or need to get your booster). If they recommend it, then listen to them.

July 2 2015 11:00 AM

Is Star Trek Tech Possible?

My friend Veronica Belmont is pretty cool. Nerd, writer, TV host… and now she’s doing an online video series with Engadget called “Dear Veronica”, where she answers tech/geek questions sent in by viewers. It’s a lot of fun.

In this week’s episode, she was asked, “Which Star Trek technologies will still be invented? Which are truly impossible and will never happen?”


Hey, I like Star Trek! So I’m really glad she asked me to field this question.

That was fun to record. But it was hard, too, since I only had 30 seconds, which didn’t give me much time to really dig deep.

But hey, I have space on the blog (haha – “space”! I kill me) so why not give a little more detail here?

Before we get started: Almost everything below is conjecture, based on physics as we know it. But I’m not an expert in all these fields, and I’ve been known to be wrong before. If you have better evidence, please let me know! Also, I’m assuming no major breakthroughs that negate or heavily modify the laws of physics as we see today. Keep that one in mind. All of these might be possible, but would involve huge breakthroughs that seem pretty unlikely to me — still, I'm no curmudgeon, and I'd love to see any of these technologies come true. I’m also trying to be brief here, to cover a lot of the quadrant. If you want details, Commander Riker might have already looked it up for you.

So let’s leave spacedock and take these ideas out for a shakedown cruise.


There are lots of problems with the idea of going faster than light. You can’t just accelerate past it like you can the speed of sound; it would take infinite energy according to relativity. And relativity tends to be right.

Other ideas include making a warp bubble, or punching a hole through space, or wormholes, but they all still have the same problem: causality. Moving faster than light is like time travel, and that opens up an entirely new can of Gagh.

So, I’m giving this a Nope until proven otherwise.

Phil Plait
I'm an adult.

Photo by Phil Plait


In Trek, they’ve said many times that the transporter works by converting someone to energy, beaming that across space, and then re-matterizing them. The problem with this is that converting a standard redshirted human body (say, 50 - 70 kg) into energy is the equivalent of detonating well over a thousand 1-megaton nuclear bombs, which is a lot.

Even if you can contain that, how do you record someone’s “pattern”? That’s a lot of information. A lot. Theoretically, there’s an equation that describes every single subatomic particle in your body, but it’s a tad complex. Describing a hydrogen atom is already pretty hard, but put ten of them together and it gets fantastically complex. There are very roughly 1028 atoms in your body. That’s a big equation.

A better retcon would be to say you’re creating a subspace tube, encasing the traveler in a small force field, and plunging them through it. But even then, I don’t think subspace is quite so much real.

So: Nope.


Phasers are like lasers but instead they start with a digraph.

OK, how they work is never really stated, but I heard from a friend who worked on Next Generation that they don’t vaporize you, they send you into subspace, where you die (see “Transporters”, above, except don’t use a force field). That’s clever, and I like it, but again with the not-real subspace.


Artificial gravity/Inertial Dampening

These are tough. As far as we know now, there’s no way to do either (well, you can spin a spaceship to mimic gravity, but that has other complications; and besides, is clearly not what they mean by the term in Trek). These are fundamental properties of space and mass, and as far as we know, the laws of physics give these a big Nope.


Replicators work on the idea that once you convert something to energy, you can then reconstitute it back as a different kind of matter. Cool, but transporters don’t work, so Nope.


Now we’re getting somewhere. Lots of things a tricorder can do we already have tech for. Infrared meters can read your temperature from a distance. Phones can listen for sounds, and do some basic image stuff too. This idea is based on reality well enough that there’s an X Prize for it.

So: Yup. Eventually, and kinda sorta now.


Please. A device for talking to people over long distances that you have to flip open? What is this, the 2190s?

Wil Wheaton
This guy probably knows all this stuff already.

Photo by Phil Plait


The idea of teeny tiny machines that can be programmed to do simple tasks doesn’t strike me as being all that far-fetched. We have some basics of this developed now. They’re a far cry from nanites escaping and taking over our (nonexistent) FTL starship, but this field is interesting. I wonder if they could be made generic such that in tandem they can do more complicated tasks. This sounds more like an engineering problem than one of physical laws, so I have to give this one a Maybe.

Force fields

The term force field is pretty generic. If you have a dense (strong) enough magnetic field it can deflect charged subatomic particles (electrons and protons) away from you, so in a sense we have those now. But something that can protect you from the force of an explosion, deflect bullets, and so on? I’m not even really sure how that would work.

But ignorance is no excuse, so to be honest I’ll give this a Maybe, just not according to what we know now.


I love this. YES. In principle, this can be done. You just need to deflect any photon coming at you from any direction so that once it’s past you it continues on in that direction.

Or, you could, for example, surround yourself with a device that can both detect and emit photons. It absorbs a photon, figures out what direction it came from, then finds the emitter on your opposite side and tells it to shoot off a photon of the right energy in the right direction. If you’re sitting still, and the light source isn’t changing, this should work. If you’re moving, then you better have really fast processors on your cloaking computer.

This would be very hard to build, and might be clunky, but it doesn’t violate any laws of physics, so I give this a Yes.

Universal Translator

We already have primitive but sortof effective translators online now. However, these take previously known languages and basically do really fast table lookups of the translations. This won’t work for an unknown language, let alone the squeals, grunts, clicks, whines, buzzes, pheromone exudate, cilia waving, and rapid eye blinks used in alien language. In Trek, that thing basically reads minds, so I’m pretty skeptical. Nope.


An elevator that goes up, down, and sideways? Willy Wonka had one of those in the 1960s.

Tractor Beam

In Next Gen they refer to the tractor beam — a device that can grab distant objects and be used to tow them — as using gravitons. These are theoretical particles that mediate the force of gravity in quantum mechanics, like photons mediate electromagnetism. However, gravitons have never been detected, and may not actually exist, which is a prerequisite for actually, y’know, existing. That doesn’t mean they don’t, it just means that a tractor beam is speculative, so I can’t give it the thumbs-up here. But Maybe, someday.

Artificial Intelligence

This is a funny one. I won’t worry about the existential issues of what intelligence is, because that’s a rabbit hole I don’t want to go down (though in detail it’s important; is intelligence an emergent property of anything that has enough complexity, or is it something that has to be specifically built into the hard/wetware?). But if we accept that humans possess intelligence, can we replicate it in non-human devices?

In principle, I have to say yes. But I wonder if we’re going about it the right way. Our brains simply don’t work like computers, despite the scifi trope. But if we can build machines that process information more like our brains do, then perhaps intelligence will emerge.

I’m no expert, and I’m spitballing here, but clearly it isn’t easy. I’ve been hearing that we’re just 25 years away from true AI for the past 40 years. Every time some breakthrough is made, it shows us that things are still a lot harder than we thought. Still, evolution seems to have done this naturally after just cooking slightly polluted hydrogen for a few billion years. People whose brains work a lot better than mine are working on it, too, and they seem to think it’s possible. So who am I to say no? Until proven otherwise, I’ll go with Maybe.

To Boldly Go…

So where does this leave us? Beats me. But whether the tech or the science of Trek is real or not, I still love the show. And while this stuff is fun to think about, they’re not the point of the show.

The point is the story, and the story is fun.

So: Second star on the right, and straight on ‘til morning. Engage.

July 2 2015 7:00 AM

C’mon, How Much Weirder Can Pluto Get?

Seriously, Pluto, what the heck are you up to?

As New Horizons gets closer every day, more details on the tiny world come into view. The latest? A very weird set of four similar dark streaks on the surface, stretching for hundreds of kilometers, and fairly evenly spaced.

Pluto and Charon
Pluto and Charon on June 27, 2015. The four dark streaks are on the image on the right.

Photo by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute


What the WHAT.

Those streaks are really too small to say much about them just yet. Although seen on older images blurred together due to low resolution, they only appear individually on images from Saturday, when New Horizons was close enough to see them and Pluto had rotated them into view (grayscale pictures from the long range camera were combined with lower resolution natural color images from another camera called, seriously, Ralph). The probe is only taking a few pictures per day as it approaches, trying to keep data storage to a minimum to save bandwidth for the big show coming in just over 11 days now.

It’s possible they’re multiple impact sites, but that seems really unlikely. They’re so evenly spaced… they’re also located very near the equator, and on the hemisphere pointed toward Pluto’s moon Charon. There’s been some suspicion that Pluto might be geologically active, spewing out jets of some material. Neptune’s moon Triton has dark geyserlike plumes, probably nitrogen from under the surface mixed with dust or some other dark substance.

Also, Triton (like Pluto) is a Kuiper Belt Object, an icy and rocky body from the outer solar system, captured by Neptune. Hmmmm.

What could drive such activity on Pluto? On Earth (or rather, under it) it’s the hot mantle moving under the continental plates that causes our tectonic activity. For Io’s volcanoes and the geysers of Enceladus (moons of Jupiter and Saturn) it’s tides from their parent planets.

Pluto and Charon are locked in both orbit and spin, so the tidal forces should all be balanced … now. However, it’s thought that Charon may have formed after a big impact on Pluto, blasting material into orbit that coalesced to form the moon. For some time after that event there would have been considerable tidal stress on Pluto, and the jets may have been active back then, leaving their marks on the surface.

The same is true for Charon as well, and the tides on it would be 10 times larger (since Pluto has 10 times the mass of Charon). Note that Charon is a lot darker than Pluto. Did it have even more activity than its big brother?

With close encounter just a week and a half away, we’ll be getting more amazing pictures every day. Unfortunately, New Horizons will be dipping low over Pluto’s opposite hemisphere from these weird features, so we won’t get super close-ups of them. But we’ll certainly get some better shots over the next few days.

This is getting so exciting! Stay tuned.

Update, July 2, 2015: I originally said the streaks were only seen in the June 27 data, but I meant that they were only seen individually after then. Also, the probe is taking only a few pictures to save bandwidth, not data storage as I originally said. It takes a long time to send back each image. After closest encounter we'll be receiving images for many months.

July 1 2015 11:37 AM

Carreyed Away

On Tuesday, California Gov. Jerry Brown signed SB-277 into law, removing the ability for parents to opt out of vaccinating their public school-age children for personal and religious exemptions.

In the wake of this, I knew the anti-vaccination cavalry would be mounting their steeds. What I wasn’t expecting was a series of tweets from actor Jim Carrey, showing exactly why those of us on the side of reality cannot rest, even after a lovely legislative victory.


Jim Carrey is a comedic actor, and I’ll note that I quite like a few of his movies and performances. But I stopped going to the theater to see them a few years ago, after he hooked up with Jenny McCarthy and joined her on her bizarre and fact-free crusade against one of the most successful medical procedures of all time.

He’s been vocal in the past; in 2009 he wrote an anti-vax screed for the Huffington Post (the journalistic equivalent of the Mos Eisley tavern for anti-vaxxers)*, and he joined McCarthy to publicly defend the disgraced and humiliated doctor Andrew Wakefield, whose unethical research, retracted paper, and conflicts of interest started the modern anti-vax movement and earned him an accusation of fraud from the British Medical Journal. When they were together, he and McCarthy were the public face of the anti-vax movement, promoting the long-debunked notion that vaccines cause autism.

But this hasn’t stopped Carrey. Tuesday night he went on quite the rant on Twitter, sending out a series of tweets that were, to be charitable, completely wrong. Let’s take a look.

Greed? Ah, a variation on the “Big Pharma shill” gambit, the claim that somehow pharmaceutical corporations make huge amounts of money on vaccines. Actually, if money were the only reason they did this, it would be far more profitable for those companies to let people get sick. Hospital and clinic visits make them way more money.

One of the basic claims made by anti-vaxxers is that there are toxins in vaccines. But there are toxins in everything. The concern isn’t that they’re there, it’s in the amount. Eating one aluminum atom won’t have any effect on you, and people tend to have a few dozen milligrams in their bodies all the time. Not all vaccines have aluminum in them, and ones that do have it in such a teeny amount it has negligible effect on you.

As for mercury, hang on a sec …

Yes, this does make sense! That’s because Carrey, despite having a vast amount of information literally at his fingertips, doesn’t understand the difference between ethylmercury and methylmercury.

Methylmercury (with an M) is a form of mercury that is bioaccumulative—that is, it builds up in the body over time. People get it in their systems in a number of ways, including eating some fish.

Ethylmercury (with an E) does not bioaccumulate, and breaks down after a couple of weeks, and your body eliminates it. Thimerosal, which used to be used in many vaccines, breaks down into ethylmercury. This process is quite safe, but after a public outcry spurred by misinformation and confusion on these two forms of mercury, thimerosal was discontinued in most vaccines. It’s now used in very small doses only in some flu vaccines.

Also? It’s been shown, conclusively, that there is no connection between thimerosal and autism. None.

Yes, Mr. Carrey, you are anti-vax. You can’t pick and choose what to believe in and what not to, and then say you’re not anti-vaccine. This gambit was tried by Jenny McCarthy and by RFK Jr. It rings just as hollow with them as it does now. If you’re trying to scare people out of taking vaccines because of obviously and provably false information, then you’re an anti-vaxxer.

Saying in one breath that vaccines have done good but then in another attacking them and increasing fears of them based on nonsense puts [RFK Jr.] squarely in the anti-vax camp. It’s like saying that most UFO cases are just misidentified normal things, but the ones we haven’t identified are definitely alien spaceships that come here to stick probes in our various orifices. Acknowledging one aspect of reality and then claiming absurdities does not make you pro-science.

Speaking of which …

Here's a bit of free advice: Run, do not walk, away from comparing yourself to RFK Jr. That may not be the best line to take. For starters, he is indeed an anti-vaxxer. He’s also a conspiracy-monger, and, unfortunately, an influential one, since he does have political clout. And given that we can’t always trust our elected representatives when it comes to health issues, that makes him especially pernicious.

Jim Carrey can yell that he’s not anti-vax at the top of his lungs, but that doesn’t change the fact that he really, really is.

After his Twitter tirade Tuesday night, the replies started flowing in, and I was pleased to see just how many were against him. I guess Carrey didn’t learn the lesson from McCarthy that sometimes going on Twitter doesn’t generate quite the result you were hoping for.

In the end, though, SB-277 is now law, and if you live in California you have to vaccinate your children if you want them to attend public school, unless you have a valid medical reason for not doing so. I think that’s real progress.

I’m happy to discuss the ramifications of laws like this on the basis of parental rights—as a parent myself I have very strong feelings about those rights. I’m also something of a social libertarian, wanting most rights to lie with the people, and not the government. But I also know those rights must have limits, because people make mistakes and in some cases need to be regulated.

The health and welfare of the public certainly constitute one of those cases. So again, I thank Gov. Brown, and I hope many more states follow suit.

*Correction, July 1, 2015: This post originally misspelled Mos Eisley.

July 1 2015 7:00 AM

Which Hunt?

In early June, Nobel laureate Tim Hunt was asked to speak at a luncheon sponsored by the Korea Federation of Women’s Science and Technology Associations at a science communications meeting in South Korea.

What he said there is now Internet history. He made a series of sexist comments, saying that the problem with “girls” in science is that they fall in love with the men; the men fall in love with them; and when you confront them, they cry. He then went on to suggest labs should be single-sex.


When I first read this, I figured it was a joke. A very poorly conceived one, and a really dumb one to make, especially given that crowd. But there’s a lot more to it than that.

Many science journalists were at the lunch and witnessed the whole thing, including Deborah Blum, Ivan Oransky, Charles Seife, and Connie St. Louis. After discussing what they saw and heard, they decided St. Louis should write an article about it in a blog post at Scientific American.* What’s very important to note here is that both Blum and Oransky have corroborated St. Louis’ report, multiple times. Seife did as well. Blum asked Hunt about his comments, and he confirmed that he thought women were too emotional to work with men in labs.

In other words, it’s clear that even if he framed it as a joke, he was being sincere in his meaning and intent.

Then it all hit the fan. For one thing, on Twitter, news of his comments went viral very rapidly. The hashtag #distractinglysexy went viral, an amusingly tongue-in-cheek way for women to mock the idea that women are too emotional or liable to fall in love in the lab. For another, Hunt was asked to resign from his honorary position at the University College London. He also resigned from the board of the European Research Council and the Biological Science Awards Committee of the Royal Society.

Mind you, he is a retired professor, and was not fired or asked to resign from any paying positions. He lost no employment over this, despite some people claiming otherwise.

At this point the backlash began. Richard Dawkins, who, honestly, should know better by now than to wade into controversies about sexism, defended Hunt against what he termed a “witch hunt.” However, there didn’t appear to be any organized campaign to get him fired, and furthermore the University College London says it did not ask him to step down due to the social media uproar, but because of Hunt’s own remarks.

A lot of electrons have been spilled over whether Hunt went on to say, “Now seriously…,” which would indicate he was actually joking. Seife (who, again, was there at the luncheon) says Hunt never said this.

Hunt’s comments and the defense of them were bad enough, but the situation has taken an even worse turn.

The execrable Daily Mail has waded into this. On Friday, it published what can only be called a hit piece on Connie St. Louis which, bizarrely, was endorsed by Dawkins.

To say the article is problematic is to severely understate the case. It attacks St. Louis’ credentials; however, she is an award-winning journalist, former president of the Association of British Science Writers and was recently elected to the board of the World Federation of Science Journalists. The City University London (where she is a senior lecturer) has publicly supported her after the Daily Mail article came out. St. Louis points out numerous errors in the article there as well.

Not to put too fine a point on it, the Daily Mail is to journalism what ipecac is to digestion. Also, a perusal of links to their articles running down the right-hand side of their site doesn’t exactly show them to be champions of women’s rights.

I also found it very odd that the article also dismisses statements corroborating St. Louis’ claims by Blum and Oransky (and it doesn’t even mention Seife)—who, I remind you, were all there at the luncheon and agree on what happened. Why single out St. Louis here?

And now another attack piece on St. Louis has been posted on the far-right-wing Breitbart site, saying she has become immune from criticism because she’s black.

Yes, you read that right. And that’s not all. In a sentence so tone deaf I’d swear it’s parody, the author, Milo Yiannopoulos, writes*:

St Louis is responsible for the sacking of Sir Tim Hunt, a Nobel prize-winning biochemist who became the target of an online lynch mob after his comments about women in science were taken out of context.

Yes, again, you read that right. You might ignore the obviously incorrect statements in that one sentence (Hunt wasn’t sacked, he was asked to resign from an honorary position; and as we’ve seen his comments were not taken out of context), but it’s much harder to ignore that, in an article attacking a woman because she’s black, Yiannopoulos used the phrase “lynch mob.”


Yiannopoulos, for his part, is a vocal advocate for Gamergate, a movement that claims it’s  “actually about ethics in gaming journalism” (a phrase so thin it’s become a standard Internet joke), but which has also been viciously attacking women online. Yiannopoulos appeared on the British 24-hour news channel Sky News to “debate” this topic with Dr. Emily Grossman; while glib, his arguments were unconvincing, and unsurprisingly Grossman has been receiving misogynistic backlash for her appearance (that link also shines a light on more of Yiannopoulos’ incorrect statements).

Clearly, this is quite the rabbit hole.

A lot of people are trying to squeeze this whole Tim Hunt affair in a “he said/she said” frame, but what they’re missing is twofold: Even if he was making a joke initially, he meant what he said, and that’s why he’s suffered the consequences of it, and either way this event has once again shone a spotlight on the rampant sexism in society in general and in the sciences specifically.

So what now? The good news is that at least this important issue is getting airtime, getting discussed. The problem is it’s also getting hijacked, distorted, and drowned out by nonsense. This happens every time institutionalized sexism is discussed.

As always, it’s important for men to speak up as well. This isn’t a women’s problem, clearly. It’s something we all need to be aware of and to speak up about.

And in the end, while the spotlight may be on Hunt and what he said, that light has certainly cast a very large reflection on the rest of us.

Here are other articles I’ve written on this issue:

*Correction, July 1, 2015: This post originally misspelled the last name of writer Milo Yiannopoulos. Also, I originally wrote that the article St. Louis wrote about the luncheon was for her blog, but it was for a guest post on Scientific American.

June 30 2015 1:12 PM

Pluto Grows Under New Horizons’ Watchful Eye

Right now, Pluto is about 25 pixels across in the New Horizons space probe’s long-range camera. In a week it’ll be 50 pixels across. A few days later it’ll be well to 100 … and then it’ll grow by the hour.

What will we see? I wrote about all this for my twice-monthly column for Go see! It’s subscription only, but c’mon. I’m worth it.

June 30 2015 7:00 AM

A Refreshing Illusion: Flat Glass of Water

I love fun illusions, and I happened upon one that’s pretty interesting to see: an artist draws a glass of water that is startlingly 3-D:

Oddly, the illusion is actually more convincing to watch at lower resolution and with a smaller window; that washes out the pencil strokes and actually makes the illusion more realistic. I can’t remember the last time I saw something like that.


This type of art is becoming common in street drawing; a Web search will yield a bazillion very cool examples.

This technique is called forced perspective, in that it takes the cues your eyes and brain use to estimate relative distance (like, when one object is closer than another) and plays with them, forcing you to interpret those cues a certain way.

When the artist rotates the drawing so the top of the glass is toward you, it looks all weird and distorted because your brain is confused. I love the irony; it shows you this is a drawing and not real, yet your brain may take a moment or two to actually settle with that. Our brains just love to be fooled.

My friend and evil twin Richard Wiseman* is a master at this. Watch this video he created:

Richard is a psychologist who studies things like this. I strongly urge you to watch the videos on his Quirkology YouTube channel and to read his books. It’s really good stuff.

... and please check out what I still consider the single greatest illusion of all time.

Tip o’ the Necker Cube to David Darling.

*He claims I’m the evil one, thus proving he’s the evil one.

June 29 2015 7:00 AM

Weighing a Galactic Monster 

How do you weigh a black hole?

That is, to be more precise (or pedantic), how do you figure out what the mass of a black hole is?


There are actually lots of ways, but they all depend on a very simple law of gravity: If you’re orbiting something (whether it’s a black hole, a star, a planet, or anything else), the closer you are, the faster you’ll go.

If you start there, and make a few assumptions, then all you need to do is observe stuff orbiting the black hole, figure out how quickly it’s moving, and boom. The black hole mass falls out.

Astronomers have been doing this for a long time. Observing stars in motion—literally, watching them physically move over several years—in the center of our own Milky Way galaxy shows that the supermassive black hole residing there has a mass of more than 4 million times that of our Sun.

Another way is to look at the motion of stars and gas in another galaxy. We can’t see their stars moving directly, but as they zip around the central black hole, sometimes they move toward us and sometimes away. That creates a Doppler shift, a shifting of the light emitted toward the blue and red end of the spectrum. The amount of Doppler shift depends on the velocity of the population of stars and/or gas as they orbit, and that means you can get the black hole mass that way. For example, gas in the center of the galaxy M84 was used to find its black hole has a mass of over a billion times that of the Sun!

Now astronomers have used a different way, though based on this same idea. They used ALMA, the Atacama Large Millimeter/submillimeter Array, to look at light emitted by the molecules HCN (hydrogen cyanide) and HCO (there’s no specific formal name I could find for this, but it’s a carbon atom bonded to an oxygen and hydrogen atom) in the galaxy NGC 1097. ALMA is very precise, and they were able to find both the location of the gas and its velocity.

Coiled Creature of the Night
NGC 1097 as seen by the Spitzer Space Telescope in infrared, showing the entire galaxy. The tiny ring at the center is the ring seen in the top photo.

Photo by NASA/JPL-Caltech/The SINGS Team (SSC/Caltech)

This gas orbits well outside the black hole, and there are stars there too, millions of them. To account for them (because if they don’t, they’ll get too high a mass for the black hole) they used Hubble observations of NGC 1097. They then fit a series of models, each using different black hole masses, to see which one fit the observed velocity of gas best.

Their result: NGC 1097 has a 140 million solar mass central black hole. That’s way beefier than ours. Also a bit higher than previous estimates of 100–120 million.

The reason this is important is that a lot of galaxy characteristics seem to be affiliated with how massive the central black hole is. We can only measure the motion of stars and gas near the center of nearby galaxies, but some of these other characteristics can be seen in galaxies much farther away. If we can get good measurements in different ways for nearby galaxies, we can use that to bootstrap our measurements for the more distant ones.

Also, NGC 1097 is a barred spiral galaxy, and for various reasons these can be very difficult beasts to observe and get the mass of their black holes. These new results should help resolve some of those issues.

So there you go. If you want to take the measure of a black hole, you have to see how things behave nearby it. That’s probably good advice for many things in life, but nothing more so than the heftiest single objects in the Universe.

June 28 2015 11:57 AM

Uncrewed SpaceX Falcon 9 Rocket Explodes After Launch

A SpaceX Falcon 9 rocket carrying supplies to the International Space Station exploded about 2 minutes and 20 seconds after launch Sunday morning. No people were onboard; it was an uncrewed resupply mission. The cause is not yet known.

Here is video of the event (launch is at 51:48, the explosion at 54:05):


SpaceX has not released details yet; a press conference is scheduled for no earlier than 12:30 EDT. I’ll update here when I know more.

Looking at the video, the explosion doesn’t release flames, but instead you see a vaporous white cloud blow away. My guess—and I’m no expert—is that this was a pressurized cryogenic tank failure of some kind. But again, we’ll know more very soon.

Update 1, June 28, 2015 at 16:10 UTC: SpaceX CEO Elon Musk just tweeted that it looks like a tank overpressurization event, as I had guessed:

We should know more soon.

Update 2, June 28, 2015 at 17:25 UTC: At the news conference, SpaceX President Gwynne Shotwell noted that first stage flight went well, and the problem that led to the loss of the vehicle lay elsewhere. They have telemetry from the Dragon capsule from the event, and they are investigating it.

I cannot be sure, but I think this may be the Dragon capsule falling away after the mishap.

Photo by NASA/SpaceX, from the video

Also, I think you can see the Dragon capsule falling away seconds after the explosion. This is a screen grab from a YouTube video, taken at the 54:09 mark. It’s about the right shape, and it’s not too much to think it would survive the destruction of the upper stage. SpaceX hasn’t said, so this is in no way official, but I’m speculating again that there was a tank rupture as per Musk’s earlier tweet. This would’ve led to a big blowout of gas, which caused the vapor cloud. Then the pressure of the rocket’s flight through the air led to the catastrophic collapse of the upper stage. Dragon may have just fallen away after that. It’s also possible the range officer exploded the rocket after seeing the problem. We’ll know more soon. But again, this is guesswork on my part.

The Dragon capsule on top of the rocket had food and supplies for the astronauts on ISS. The three astronauts on board have enough food to last for many months, so they should be OK for now. Also on board the Dragon was an adapter ring for the ISS that would allow future commercial vehicles easier docking access.

This is the first SpaceX failure since it began resupply missions to ISS, but the third overall failure to ISS, including the loss of a Progress vehicle in April and the Orbital Antares rocket in October of 2014. This comes at a time when the Senate has been trying (wrongly, in my opinion) to cut back on funding for SpaceX and other commercial companies, so I expect we'll see statements from those senators on this event shortly. Read them with a grain of salt. Again, we'll know more shortly. Stay tuned.

Correction, June 28, 2015, at 17:50 UTC: I originally misspelled Gwynne Shotwell's first name.