Blogs / Bad Astronomy

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.

So you’ve lived here all your life — in fact, everyone has — but what do you really know about the Milky Way galaxy? Sure, you know it’s a spiral, and it’s 100,000 light years across. And of course, BABloggees are smarter, more well-read, and better looking than the average population, but be honest: do you know all ten of these things? Really?

Liar.

So let’s see if these really are Ten Things You Don’t Know About the Milky Way Galaxy.

1) It’s a barred spiral.

You might know that the Milky Way is a spiral galaxy, perhaps the most beautiful galaxy type. You’ve seen ‘em: majestic arms sweeping out from a central hub or bulge of glowing stars. That’s us. But a lot of spirals have a weird feature: a rectangular block of stars at the center instead of a sphere, and the arms radiate away from the ends of the block. Astronomers call this block a bar, and, you guessed it: we have one.

Is fact, ours is pretty big. At 27,000 light years end-to-end, it’s beefier than most bars. Of course, space is a rough neighborhood. Who wouldn’t want a huge bar located right downtown?

By the way, the image above is not a photograph, it’s a drawing– there’s no way to get outside the galaxy and take a picture like this looking back. It would be a loooong walk home! Click the picture to embiggen and get more details (which is true for all the pictures in this post).

2) There’s a supermassive black hole at its heart.

At the very center of the Galaxy, right at its very core, lies a monster: a supermassive black hole.

We know it’s there due to the effect of its gravity. Stars very near the center — some only a few dozen billion kilometers out — orbit the center at fantastic speeds. They scream around their orbits at thousands of kilometers per second, and their phenomenal speed betrays the mass of the object to which they’re enthralled. Applying some fairly basic math, it’s possible to determine that the mass needed to accelerate the stars to those speeds must tip the cosmic scales at four million times the mass of the Sun! Yet in the images, nothing can be seen. So what can be as massive as 4,000,000 Suns and yet not emit any light?

Right. A black hole.

Even though it’s huge, bear in mind that the Galaxy itself is something like 200 billion solar masses strong, so in reality the black hole at the center is only a tiny fraction of the total mass of the Galaxy. And we’re in no danger of plunging into it: after all, it’s 250,000,000,000,000,000 kilometers away.

It’s thought now that a supermassive black hole in the center of a galaxy forms along with the galaxy itself, and in facts winds blown outward as material falls in affects the formation of stars in the galaxy. So black holes may be dangerous, but it’s entirely possible the Sun’s eventual birth — and the Earth’s along with it — may have been lent a hand by the four million solar mass killer so far away.

3) It’s a cannibal.

Galaxies are big, and have lots of mass. If another, smaller galaxy passes too close by, the bigger galaxy can rip it to shreds and ingest its stars and gas.

The Milky Way is pretty, but it’s savage, too. It’s currently eating several other galaxies. They’ve been ripped into long, curving arcs of stars that orbit the center of the Milky Way. Eventually they’ll merge completely with us, and we’ll be a slightly larger galaxy. Ironically though, the galaxies add their mass to ours, making it more likely we’ll feed again. Eating only makes galaxies hungrier.

4) We live in a nice neighborhood…

The Milky Way is not alone in space. We’re part of a small group of nearby galaxies called — get ready to be shocked — the Local Group. We’re the heaviest guy on the block, and the Andromeda galaxy is maybe a bit less massive, though it’s actually spread out more. The Triangulum galaxy is also a spiral, but not terribly big, and there are other assorted galaxies dotted here and there in the Group. All together, there are something like three dozen galaxies in the Local Group, with most being dinky dwarf galaxies that are incredibly faint and difficult to detect.

5) … and we’re in the suburbs.

The Local Group is small and cozy, and everyone makes sure their lawns are mowed and houses painted nicely. That’s because if you take the long view, we live in the suburbs. The big city in this picture is the Virgo Cluster, a huge collection of about 2000 galaxies, many of which are as large or larger than the Milky Way. It’s the nearest big cluster; the center of it is about 60 million light years away. We appear to be gravitationally bound to it; in other words, we’re a part of it, just far-flung. The total mass of the cluster may be as high as a quadrillion times the mass of the Sun.

6) You can only see 0.000003% percent of it.

When you got out on a dark night, you can see thousands of stars. But the Milky Way has two hundred billion stars in it. You’re only seeing a tiny tiny fraction of the number of stars tooling around the galaxy. In fact, with only a handful of exceptions, the most distant stars you can readily see are 1000 light years away. Worse, most stars are so faint that they are invisible much closer than that; the Sun is too dim to see from farther than about 60 light years away… and the Sun is pretty bright compared to most stars. So the little bubble of stars we can see around us is just a drop in the ocean of the Milky Way.

7) 90% of it is invisible.

When you look at the motions of the stars in our galaxy, you can apply some math and physics and determine how much mass the galaxy has (more mass means more gravity, which means stars will move faster under its influence). You can also count up the number of stars in the galaxy and figure out how much mass they have. Problem is, the two numbers don’t match: stars (and other visible things like gas and dust) make up only 10% of the mass of the galaxy. Where’s the other 90%?

Whatever it is, it has mass, but doesn’t glow. So we call it Dark Matter, for lack of a better term (and it’s actually pretty accurate). We know it’s not black holes, dead stars, ejected planets, cold gas — those have all been searched for, and marked off the list — and the candidates that remain get pretty weird (like WIMPs). But we know it’s real, and we know it’s out there. We just don’t know what it is. Smart people are trying to figure that out, and given the findings in recent years, I bet we’re less than a decade from their success.

8) Spiral arms are an illusion.

Well, they’re not an illusion per se, but the number of stars in the spiral arms of our galaxy isn’t really very different than the number between the arms! The arms are like cosmic traffic jams, regions where the local density is enhanced. Like a traffic jam on a highway, cars enter and leave the jam, but the jam itself stays. The arms have stars entering and leaving, but the arms themselves persist (that’s why they don’t wind up like twine on a spindle).

Just like on highways, too, there are fender benders. Giant gas clouds can collide in the arms, which makes them collapse and form stars. The vast majority of these stars are faint, low mass, and very long-lived, so they eventually wander out of the arms. But some rare stars are very massive, hot, and bright, and they illuminate the surrounding gas. These stars don’t live very long, and they die (bang!) before they can move out of the arms. Since the gas clouds in the arms light up this way, it makes the spiral arms more obvious.

We see the arms because the light is better there, not because that’s where all the stars are.

9) It’s seriously warped.

The Milky Way is a flat disk roughly 100,000 light years across and a few thousand light years thick (depending on how you measure it). It has the same proportion as a stack of four DVDs, if that helps.

Have you ever left a DVD out in the Sun? It can warp as it heats up, getting twisted (old vinyl LPs used to be very prone to this). The Milky Way has a similar warp!

The disk is bent, warped, probably due to the gravitational influence of a pair of orbiting satellite galaxies. One side of the disk is bent up, if you will, and the other down. In a sense, it’s like a ripple in the plane of the Milky Way. It’s not hard to spot in other galaxies; grab an image of the Andromeda galaxy and take a look. At first it’s hard to see, but if you cover the inner part you’ll suddenly notice the disk is flared up on the left and down on the right. Andromeda has satellite galaxies too, and they warp its disk just like our satellite galaxies warp ours.

As far as I can tell, the warp doesn’t really affect us at all. It’s just a cool thing you may not know about the Milky Way. Hey, that would make a good blog entry!

10) We’re going to get to know the Andromeda galaxy a lot better.

Speaking of Andromeda, have you ever seen it in the sky? It’s visible to the naked eye on a clear, dark, moonless night (check your local listings). It’s faint, but big; it’s four or more degrees across, eight times the apparent size of the Moon on the sky.

If that doesn’t seem too big, then give it, oh, say, two billion years. Then you’ll have a much better view.

The Andromeda Galaxy and the Milky Way are approaching each other, two cosmic steam engines chugging down the tracks at each other at 200 kilometers per second. Remember when I said big galaxies eat small ones? Well, when two big galaxies smack into each other, you get real fireworks. Stars don’t physically collide; they’re way too small on this scale. But gas clouds can, and like I said before, when they do they form stars. So you get a burst of star formation, lighting up the two galaxies.

In the meantime, the mutual gravity of the two galaxies draw out long tendrils from the other, making weird, delicate arcs and filaments of stars and gas. It’s beautiful, really, but it indicates violence on an epic scale.

Eventually (it takes a few billion years), the two galaxies will merge, and will become, what, Milkomeda? Andromeway? Well, whatever, they form a giant elliptical galaxy when they finally settle down. In fact, the Sun will still be around when this happens; it won’t have yet become a red giant. Will our descendants witness the biggest collision in the history of the galaxy?

That’s cool to think about. Incidentally, I talk about this event a whole lot more, and in a lot more detail, in my upcoming book Death from the Skies! In case you forgot about that.

Until then, these Ten Things should keep you occupied. And of course, I only wanted to list ten things so I could give this post the cool title. But if there’s something you find surprising about the Milky Way, leave a comment! I don’t want to hog all the fun.

OK, so I take a day off from blogging and the world, surprisingly, kept spinning. So here’s some stuff to keep you busy while I figure out what to write about next:

1) Jules Verne is the name of a very cool and highly sophisticated robotic vehicle built by the European Space Agency to aid astronauts on the space station. There were some initial problems with it, but it’s fixed.

2) The Large Binocular Telescope is a massive pair of 8.4 meter mirrors (cripes!) that work together to act as one very impressively ginormous telescope. One of the mirrors has been used for some time, but the second just came online and they have released their "First Light" image. Editorial note: I have no clue why they picked such a boring object for this image. It’s winter! They could have done any number of awesome things in Orion, or Gemini, or taken a shot at Saturn. Oh well.

3) A new website called Space Advocates for Obama has been set up. I need to look through it (busy busy) but it looks like a good place to get info on what Obama thinks on this important topic. If anyone knows of similar sites for Clinton and McCain, please post a comment below!

4) Real Climate, a blog written by professional climate scientists, has an interesting post up about the effects of the Sun’s motion through the galaxy and galactic cosmic rays on our climate. I researched this quite a bit for my book, and interviewed one of the writers of RC, Caspar Ammann, about it as well. This is an area of active research, and as such it’s hard to make firm statements just yet, but it’s looking like cosmic rays don’t affect the climate at all or at most the effect is very subtle.

5) Good news everyone! I Heart Chaos has an online and nearly complete timeline of Futurama events! It’s amazing, and if you’re a fan you’ll get a kick out of it.

Mark your calendars! Spacefest 2009 will be held on February 19-22, 2009, in San Diego, California!

Spacefest is a convention for space enthusiasts. The inaugural meeting was last year, and it was a tremendous time (see my reports here, here, and here). Almost every living astronaut who walked on the Moon was there, and let me tell you how thrilling that was! I was there to give my Moon Hoax talk, and Carolyn Porco gave a tremendous speech about Cassini. Andy Chaikin gave an Apollo talk (his book A Man on the Moon is considered to be the Bible of Apollo, and Tom Hanks based his HBO miniseries "From the Earth to the Moon" on that book). My buddy Seth Shostak from SETI was there, as well as famed comet hunter David Levy.

I’m not sure who will be there next time, though many astronauts have already signed up. I have as well! I’ll have to find something else to talk about, but happily I’ll have a new book to plug, so I’m sure I can come up with something.

Here’s a taste of what to expect…