Blogs / Bad Astronomy

There has been news around the blogosphere this week about an ancient artifact that might indicate that Sumerians saw an asteroid impact… and that it might explain Sodom and Gemorrah. Pretty much everything about that press release set off my BA detector, and I was going to write about it. But then I saw that my friend and asteroid-namer-after Jeff Medkeff already tackled it with much gusto.

I’ll be very curious to see if more about this idea turns up any time soon.

GRB080319b, the explosion that shook astronomers by getting bright enough to be seen with the naked eye, is still going strong. Hubble snapped this image three weeks after the explosion:

Incredibly, even after that time the GRB afterglow is still brighter than its host galaxy! This was truly an incredible event. I imagine any potential aliens in that galaxy — at least between us and the burst — are just so much vapor now. Of course, you can think of this event as having happened 7.5 billion years ago, so it’s unlikely that there are any alien civilizations around to be destroyed (as I mentioned in an earlier post, heavy metals were rarer back then, so planets would probably have been deficient in elements like iron, calcium, zinc, and so on). Maybe whole planets-full of microbes were zapped, though.

GRBs emit their light in beams like a flashlight, which is why they are so bright even from so maddeningly far away. But this one was so bright that astronomers were at first a little baffled. Was this really an astonishingly luminous event, or did the beam from the GRB happen to be perfectly aimed at us? Did it hit a bulls-eye?

In fact, it’s thought that this truly was an incredibly luminous event intrinsically, and that was due to the beam being unusually tightly focused. It also was aimed right at us, making it look even brighter.

What’s fun to think about is how many other GRBs have been like this one? Probably not many, actually, so it was good for us that we happened to have the Swift satellite operating when the GRB went off. That allowed us to observe the explosion in near real-time with bigger and more sensitive telescopes, and in turn learn more about these incredible explosions on the dim edge of the Universe.

And I’ll add that this couldn’t have happened at a better time for me: I was able to edit the proofs of my book to include GRB 080319b! I had talked about an earlier burst originally, but substituted this one in for it. I’m glad the timing worked out so well.

Just a little update on Death from the Skies! I got the laid-out version last week; a hard copy that is printed the same way it will be when it’s in book form. It has pictures and everything! Very cool.

I’m going through it looking for mistakes. Even after so many eyes have been on it, there are still some, since it had to be converted from copy-edited version to galley proof (which means transcription errors). My favorite is when a exponent gets un-superscripted, so, for example, 10²⁰ becomes 1020. That makes me laugh, since it changes the number a wee bit.

Anyway, I’m going through the last chapter now, and even though I have now read this book like five times, I’m still enjoying reading it. That means everyone else will worship it and it will sell a bazillion copies. Right?

Hrmph.

Anyway, I’ll be done soon, and then there won’t be much left for me to do with it except wait patiently for it to come out in October.

I linked to this subtly in my post about my trip to the UK next month to visit Europe’s new particle accelerator, the Large Hadron Collider (LHC), but it deserves more attention.

Two men are suing to stop the LHC from being switched on, saying it may be dangerous and might even destroy the Earth:

But Walter L. Wagner and Luis Sancho contend that scientists at the European Center for Nuclear Research, or CERN, have played down the chances that the collider could produce, among other horrors, a tiny black hole, which, they say, could eat the Earth. Or it could spit out something called a “strangelet” that would convert our planet to a shrunken dense dead lump of something called “strange matter.” Their suit also says CERN has failed to provide an environmental impact statement as required under the National Environmental Policy Act.

[...]

The lawsuit, filed March 21 in Federal District Court, in Honolulu, seeks a temporary restraining order prohibiting CERN from proceeding with the accelerator until it has produced a safety report and an environmental assessment. It names the federal Department of Energy, the Fermi National Accelerator Laboratory, the National Science Foundation and CERN as defendants.

First off the bat, this sounds nuts, but really it’s not so nuts that we shouldn’t look into it. There are two causes for some concern: one is that LHC might create a black hole which would eat the Earth, and the other is that a very odd quantum entity called a strangelet might be created, with equally devastating results.

However, I don’t think there’s anything to worry about. I want to make that clear up front.

The LHC will slam subatomic particles together at fantastic speeds. The collision in a sense shatters the particles and all sorts of weird beasties are created in the aftermath. This give physicists insight into the basic quantum nature of the Universe. The higher the energy of the collision, the more interesting stuff you get. LHC will be the most powerful collider ever built, and is expected to provide really new looks at the quantum world.

That’s what has the two litigators worried.

If two subatomic particles collide at high enough speed, it’s possible that they will collapse into a black hole. If that happens, it would fall through the Earth and, well, you can guess what bad things would happen then^*.

However, studies done by CERN show that the energies generated will be too low to make black holes. Also, due to a weird effect called Hawking radiation, the tiny black holes would evaporate instantly. The two litigants, however, say that Hawking radiation is not an established fact, and therefore we should be more careful. While that’s technically true, they forgot something important: the same rules of quantum physics that make a black hole in a subatomic collision also indicate they would evaporate. So if you’re worried they won’t evaporate, then you shouldn’t be worried they’d be created in the first place.

Same goes for the creation of a quantum strangelet. This is a weird conglomeration of particles called quarks, and if a strangelet comes into contact with normal matter can convert it into more strangelets. The idea is that these can cause a chain reaction that turns all available matter into strangelets. That would be bad.

However, first, strangelets are completely theoretical, and again even if they are real it’s incredibly unlikely they would be created even by LHC. And even if they were created, the chances of them being a danger are very small. A study a few years ago by physicists at MIT, Yale, and Princeton shows this to be the case; as they point out, higher energy particles hit the Moon all the time. If strangelets could be created in this way, the Moon would have converted to a big ball o’ strangelets billions of years ago.

So I think that considering things like this happening is good — after all, we’re walking into new territory here — but in this particular case the litigants are wrong. A lawsuit seems like overkill. In fact, it’s so odd that my skeptical gland was tweaked, and I decided to look into the litigants’ backgrounds.

Walter Wagner apparently has a physics background, but was involved in a similar lawsuit over the Brookhaven collider a few years back, which turned out to be completely baseless.

As for the other, Luis Sancho, he’s, well, how do I phrase this delicately? He’s a bit outside the mainstream. Actually, way outside the mainstream. In fact, totally and way way far outside the mainstream. I don’t think you can even see the mainstream from where he is.

While dismissing the idea of any danger from LHC due to these factors would be an ad hominem and therefore unfair, I think it adds a dimension to this case that’s good to keep in mind.

Again, I’m not worried. I don’t see any basis for their fears, and certainly not for their lawsuit.

So I’m still greatly looking forward to visiting the LHC in April. It’ll be a fantastic glimpse into the next generation of physics, and will open up new vistas for us to explore.

If the court agrees to let it run, of course.

It is with great honor and no small amount of pride to announce that the asteroid 2000 WG11 shall henceforth be known as asteroid 165347 Philplait.

That’s right: I now have an asteroid named after me.

My friend, fellow astronomer, fellow skeptic, and fellow blogger Jeff Medkeff discovered the asteroid in 2000. It was given the preliminary designation of 2000 WG11, and Jeff had the privilege of naming it, and the short version is he decided it was my time.

The asteroid is about 1.3 km (0.8 miles) across, making it rather small as asteroids go. Because of that (and its current distance of 450 million kilometers) it’s a bit faint, shining right now at about magnitude 21. That’s within reach of a 12" telescope with a nice CCD detector on it, but you won’t be seeing this with your birdwatching binocs.

I don’t have any images of it… yet. It’s listed in the Minor Planet and Comet Ephemeris Service; put "Philplait" into the big text box and it will give you the coordinates of the asteroid (it’s currently in the constellation of Aries). You can see where it is in the solar system on the JPL Small Body Database Browser. Here is the map for today:

As you can see in the map, it’s a main belt asteroid, orbiting the Sun between Mars and Jupiter. It can’t impact the Earth (too bad, since that would be pretty good publicity for Death from the Skies!; I’d sell a million books — plus, the headlines would read "Philplait to Destroy the Earth!" which is awesome). If it could hit us, it would have an impact yield of at least 35,000 megatons, which is a lot, and could easily be a lot more (I’m assuming here that the minimum impact speed is 11 km/sec, Earth’s escape velocity; it could in fact be much higher). This probably would not cause an extinction level event for humans, but it wouldn’t be fun either. The asteroid that wiped out the dinosaurs was from a rock more then 8 times the diameter of 165347 Philplait^* and 500 times the mass.

To give you an idea of the asteroid’s size, it has more than 200 times the volume of Hoover Dam. Assuming that it’s made of rock, it has a mass of about 2 quadrillion grams, or about 2 billion tons. If it’s metal it’ll be about twice that massive.

The orbit is mildly eccentric, which means it’s not a perfect circle. It gets as close as about 300 million km from the Sun and as far as 400 million km (180 to 240 million miles). This keeps it well outside the orbit of Mars and well inside Jupiter’s. It’s a nice, safe, rock.

I would say having this rock named after me is a singular honor, but in fact it isn’t: three other skeptics join me in the asteroid belt: Rebecca Watson, Michael Stackpole, and, yes, PZ Myers.

Now, I know my readers, and I know what you’re thinking: whose asteroid is bigger, mine or PZ’s? I asked Jeff that as well, but first I need to take a little diversion into sizes of asteroids.

Asteroids in the main belt are in general too small and too far away to see them as anything other than unresolved dots. So we can’t measure their size directly. Instead, it’s inferred. Imagine two asteroids at the same distance from us, but one is bigger than the other. Since it has more surface area, it reflects more sunlight, and will appear brighter to us. However, the reflectivity of the asteroid also determines its brightness: a shiny white asteroid will be a lot brighter than one the same size that’s soot black. The reflectivity of an asteroid is called its albedo. Something that reflects 100% of the incoming light has an albedo of 1, while something pitch black would have an albedo of 0.

So the size of an asteroid is calculated using its distance and assuming an albedo. On average, asteroids have an albedo of about 0.15, so that’s what usually assumed. It’s also assumed that the asteroid is a sphere, which may not be true. In fact, only asteroids hundreds of miles across are spherical, so one a mile across can be any sort of weird shape.

So assuming the asteroid has an albedo of 0.15 and that it’s round, it’s about 1.3 kilometers in diameter. It could be shinier and smaller, or darker and bigger, or elongated and bigger, or or or. Until we go there and take a look we won’t know.

Having said all this, I’ll note that all things being equal, PZ’s asteroid (153298 Paulmyers) is twice the diameter of mine. Sigh. Figures. However, I’m not insulted. In fact I think PZ is overcompensating for something. Still and all, we don’t really know how big they are, but his being bigger is the safe way to bet.

Even if I must share this honor with PZ (and there better be a species of squid named after me soon to make up for this) it is still a great one. I wonder… some time in the distant future, will some astronaut mine this asteroid? Will it be someone’s home, or will it be just another rock among billions, silently orbiting the Sun?

Either way, this is totally amazing. It’s a little slice of immortality, and one I am truly touched to receive.

Holy Haleakala! Yesterday, a gamma-ray burst went off that was so bright that had you been looking at the right spot in the sky you could have seen it with just your own eyes!

It’s difficult to put this into the proper context. GRBs are monumental explosions, the exploding of a massive star where most of the energy of the catastrophe is channeled into twin beams of energy. These beams scream out from the explosion like cosmic blowtorches, and for thousands of light years anything they touch is destroyed. Happily for us, GRBs always appear hundreds of millions or billions of light years away.

Let me put this in perspective for you. Imagine a one megaton nuclear weapon detonating. That’s roughly 50 times the explosive yield of the bomb dropped on Nagasaki. Devastating.

The Sun, every second of every day of every year, gives off 100 billion times this much energy. That’s every second. A star is a terrifying object.

In the few seconds that a gamma-ray burst lasts, it packs a million million million times that much energy into its beams. In other words, for those few ticks of a clock the GRB is sending out more energy than the Sun will in its entire lifetime.

There is, quite simply, no way to exaggerate the devastation of a gamma-ray burst.

Yet for all that, they are optically faint due to their terrible distance. At billions of light years away, even the Universe’s second biggest bangs are difficult to see.

So that’s what makes GRB 080319B (the second GRB seen on 2008 March 19) so incredible: distance measurements put it at 7.5 billion light years away, yet it was visible to the unaided eye had you just happened to be looking up at the sky at that moment.

Whoa.

This is the single brightest GRB ever seen in optical light, so as you can imagine reports are pouring in from observatories all over the world right now. Anything this bright must be extraordinary, and you can bet that astronomers will be falling over themselves to observe this incredible event. We still don’t know enough about GRBS; just what mechanisms focus those beams? We know black holes are at their core, powering these events, but how do the gravity and magnetic fields come together to generate forces like this? How tightly focused are the beams? Do they open at a one degree angle? 5? 10? Why does every GRB behave somewhat differently, with some lasting for seconds and others for minutes?

And why was this one so frakkin’ bright? Was it a more energetic explosion itself, or were we, by coincidence, looking precisely down the center of the beam? If the beam of a GRB is pointed ever-so-slightly away from us, so that the edge nicks us, the GRB will look fainter. By staring down the throat of a GRB we’d see it as bright as it could possibly be. Maybe GRB080319B had us dead in its sights.

Watching the extremes of GRB behavior can help us constrain the more normal aspects of them… if you can even use the word "normal" when it comes to such titanic explosions on these scales. There is a fascination we humans have with such terrible events, an atavistic thrill even when our puny brains can’t comprehend the size and scale of them.

I wrote about GRBs extensively for my book Death from the Skies!, and spent a lot of time working through the math and thinking about the destruction they can wreak. If you want to know what my nightmares look like, then GRBs are a good place to start. I’m just glad there (most likely) aren’t any stars nearby that can do this. I like GRBs… when they’re far, far away.

I was recently interviewed by Dale Basler and Brian Bartel from Lab Out Loud, a podcast for the National Science Teachers Association, and it’s now online. I was a member of NSTA for several years back when I was doing education workshops at Sonoma State University. They do great work for teachers across the country, equipping them with the science they need to educate students, so I was really happy to do the interview.

We talked about eggs and the equinox, my first and second books, and spent most of our time talking about the need for skepticism, especially in the classroom. I suggest going to their site and taking a look around, or you can download the interview MP3 directly.

Turns out they had a warmup interview with someone else as a prelude, an apertif if you will, for mine, too. Think of it as a calamari appetizer.