This has been an interesting BABlog week! I decided to dome some ‘splainin, and it’s gone a bit farther than I expected. We covered galaxies, black holes, a weird moon, and a big chunk of the old electromagnetic spectrum.

That last bit is really something. I have found that despite it being a national science standard for middle school, most people understand the EM spectrum fairly poorly. There are lots of reasons for this, and I won’t go into them here. Instead, I’ll show you how cool looking at things with “different eyes” is.

Oh, wait. I don’t need to do this. I have friends who already have! The folks at the Spitzer Space Telescope have a pretty good outreach group, and they have a wonderful series of web pages called Cool Cosmos. That’s a pun, actually: Spitzer, which is an infrared telescope, looks at objects considered to be cooler than your typical cosmic objects like stars and nebulae.

Anyway, they have a page there called The Multiwavelength Astronomical Gallery, where they have images of lots of objects in different wavelengths of the EM spectrum. Most objects look pretty when viewed in optical light, but by checking out their appearance in, say, X_rays, you can see if they have magnetic fields, or black holes, or other exotic phenomena lurking in their hearts.

And sometimes it’s just weird. What do you think this thing is?

Give up? It’s the Moon! Yes, really! It was taken by the 140 foot radio telescope in West Virginia. The red parts are brighter in radio, and represent warmer regions of the Moon. The Moon was probably a few days past full when this image was made.

That page has pictures galore of galaxies, nebulae, planets, and all sorts of beautiful and weird objects. Perusing the rest of the site is a treat as well. It’s always best to learn stuff by having fun, and you get to see some amazing images as a bonus.

So take a look. It’ll open your eyes.

This doesn’t look much like a telescope, does it?

But it is! Sure, it looks like a bunch of steamer trunks lashed together, but it’s actually the imaginatively-named “Large Area Telescope”, or LAT, the main instrument that will be part of the Gamma-Ray Large Area Space Telescope (GLAST), a major NASA mission due to launch in 2007. GLAST is designed to observe high-energy gamma rays, which are just like the visible light photons we see with our eyes, but much more energetic.

As I mentioned in this blog entry from Monday, the kind of light an object emits depends on the energy of the object. Gamma rays are very high energy (millions or billions of times the energy of optical light), so it takes a pretty serious event to make them. For example, exploding stars, superdense neutron stars with magnetic fields a quadrillion times the strength of the Earth’s, tortured matter heated to millions of degrees and focused into tightly-collimated beams as it screams away from a black hole– these are the kinds of things I’m talking about.

Up until now, we’ve had only a fuzzy view of these objects. That’s because, unlike visible light, it’s nearly impossible to focus gamma rays. They don’t act like regular photons: they’ll pass right through the glass or metal in a mirror, for example. So you need to have some exotic designs for your detector to be able to figure out where any given gamma ray comes from.

The LAT can do it. It uses those 16 towers in the picture. Wanna know how? More importantly: are you ready for this?

Each tower consists of a stacked series of layers– 36 of them. Each layer has a series of interleaved silicon strips, sort of like wicker. When a gamma ray photon smacks into the tower material, it creates an electron-positron pair. These travel down to the bottom of the tower and into a device called a calorimeter, which is used to determine how much energy the pair of subatomic particles has, which in turn tells the LAT how much energy the original gamma ray had. The position on the sky (what part of the sky it came from) of the incoming gamma ray is determined by back-tracking the path of the electron-positron pair (like looking at skid marks on the road to see where a car came from before it crashed, or tracing footprints in the sand) through the layers. The LAT is accurate enough to pin down the gamma ray location to about 0.5 arcminutes in the sky (for comparison, the Moon is 30 arcminutes across). That’s a lot better than any gamma-ray observatory previous to GLAST.

The process is actually hugely more complicated than this, of course. The LAT was designed at Stanford, where lots of smart people hang out and build things like this, so it’s bound to be complex.

Below is a schematic of a LAT tower. When all 16 are put together like in the picture above, the assembly is a couple of meters across. It’s pretty big.

When it gets into space (Earth’s air absorbs gamma rays, so you need to get up above the atmosphere), the LAT will be the Hubble of gamma rays. We’ll have better views of monstrous black holes gobbling down matter, viciously spinning pulsars blasting out energy, and supernovae explosions which generate gamma rays as they ferociously accelerate electrons in their magnetics fields even as they alchemically brew the elements in our blood and bones.

I’ll add that the majority of my funding at work for the past five years is from GLAST, so it’s pretty cool to be able to finally write something about hardware getting built (and being part of the team is how I got access to that picture of the towers, which was released just earlier today!). When you’re building a new observatory, it takes a long time before you can actually start cutting metal. It’s great to see that this fine observatory is finally on its way!

I’m an astronomer, not a geomorphologist.

No, I didn’t make that word up (though I thought I did before checking Wikipedia). A geomorphologist studies the structures of landforms and tries to figure out how they got that way. I guess I do that professionally for some objects (planetary nebula, supernova remnants, and esoteric stuff like that), but not for planets and moons. That’s a confusing job, so I leave it to the other professionals. When I do it, it’s speculation for my own amusement (or in this case, I hope, for yours too).

And it’s places like Hyperion, a moon of Saturn, where I know I’ve made the right choice. The Cassini probe took some close-up snapshots of the weirdo little iceball recently, and look what it saw:

Click image for a bigger version, or here for a huge one, from The Planetary Society blog page. All images are courtesy of NASA/JPL/Space Science Institute, and CICLOPS.

What a mess! I have no desire to try to figure this one out.

OK, that’s a lie. I’d love to know what makes this look like a big old loofah sponge. There are two things that strike me about the image. Well, three, if you count the fact that Hyperion is completely freaking weird.

The first is the enormous crater. It’s really big, but is it shallow? It’s hard to say what the depth is from just one picture, but it sure looks shallow. From the appearance of all the other craters, Hyperion looks very fragile to me, crumbly even (what material scientists call friable). An asteroid smacks into it, and the crater collapses back on itself. You get rims, and steep walls, but the crater fills in. If the impact that created that crater had been any bigger, I bet it would have shattered the moon, much like Saturn’s moon Mimas and its scary big crater Herschel. ^*

The second thing are all the little craters. It’s covered with them! In some icy moons, the craters get covered over when the ice melts under a new impact, or some other event washes over the surface. Not Hyperion. Those craters look pretty fresh.

Weirder even, when you look at closeups, the craters all have black stuff at the bottom. What’s that? They aren’t shadows; the angles are all wrong. It’s actual black stuff.

In that image, you can see it, and you can also see how the walls of the craters have slumped. I would expect the junk at the bottom to be made of the same material as the stuff in the walls, but I’m not so sure. Why is it black? I think (that is, I’m speculating), that the material turned black after the walls slumped. See the crater in the upper right of the closeup? The landslide from the slump appears to partially cover up the black stuff on the bottom, implying the black stuff turns black in a separate event. Maybe this crater had a second landslide, covering up the stuff that had turned black from the first landslide.

Weird, weird, weird. Even for a moon of Saturn.

I’ll remind you again, I am not a geomorphologist. Anything I say here is speculation on my part. But I’ll be keeping an eye out for word form the real scientists working on this. Hey! Come to think of it, I’ll be meeting Cassini Imaging Team Leader Carolyn Porco at James Randi’s The Amaz!ng Meeting 4 in January (in fact, I’m introducing her, gloat gloat). I’ll ask her then.

Until then, I’ll have to settle for more speculation, while I peruse the raw Cassini images of Hyperion. You should too. Take a look at how odd, how mysterious, and how wonderful our solar system is, and think about how much more there is to see.

* Now, after writing this, I wonder… that crater is nearly the size of the moon. That strikes me as not possible. Some scientists are wondering how solid comets are; maybe they are more like rock piles held together by ice. It’s not beyond my imagination that Hyperion (which is icy like a comet) could have had hollow pockets in it, maybe where there was frozen gas. I’m wondering now if it was a smaller event, and the impact heated the volatile gas, which escaped, causing a much larger slump than the impact itself could have caused. Think of driving a nail into a shaken soda can and you’ll get the idea. Hmmm… speculation is fun, and it’s free.

Yesterday, I talked briefly about what infrared images can tell us about dust in spiral galaxies. In a funny coincidence, the European Southern Observatory put out a press release today about a new image that discusses a similar topic! In this case, though, the arms lead down to a bottomless pit: a black hole in the center of a spiral galaxy called NGC 1097.

Galaxies are vast collections of stars, gas, and dust. At first glance, NGC 1097 looks like a fairly typical spiral galaxy:

Pretty, isn’t it? Our Milky Way would look a lot like that from a few million light years away, too.

Sometimes, this kind of galaxy is called a “grand design” spiral, because the spiral pattern is so big and obvious. But what’s interesting is what happens when you zoom in on the nucleus:

The blobby ring there is a circle of dense clouds of gas and dust forming stars. But if you look carefully, you can see that the dust inside the ring is forming a spiral pattern, and it looks like it’s swirling down into the nucleus! This image has incredible resolution, rivaling Hubble’s for seeing small objects. The astronomers then processed the image a bit to bring out faint details, and made this way cool image:

The dark ellipse is the region in the image where they enhanced it. With the brighter glow suppressed, you can actually clearly see the dust arms dropping right down into the center of the galaxy! And what happens there? Well, it’s too small to be seen in these images, but inside that galaxy, right at its very heart, is a supermassive black hole. It’s called “supermassive” because it tips the cosmic scales at about a million times the mass of the Sun. Even then, it’s kindof small for a galaxy’s central black hole. The one in the center of the Milky Way is four times that mass.

Anyway, that dust from the outer part of the galaxy core is falling into that black hole. As it falls in, it forms a disk called an “accretion disk”, which gets very hot. The disk is like a holding pattern for the gas, a place to pile up before it falls into eternity. Since the disk gets hot, it emits light. In some galaxies it gets very bright, outshining the galaxy itself — in those cases, the galaxy is said to be “active”). So ironically, even though black holes are known for gobbling down even light, they can power some of the brightest objects in the Universe!

Like I said in yesterday’s blog entry: studying the dust in a galaxy can tell us a lot about it, even about things we can’t see.

First, let me start with a gorgeous picture:

What are you looking at there? Ah, that’s a cool story… literally.

For a long time, astronomers figured visible light was all there is. In astronomy, what you saw was literally what you got.

That changed in the 20th century. Astronomers quickly found the utility of observing the sky in different parts of the electromagnetic spectrum. What we call visible light is really only a tiny portion of that wide, wide spectrum of light, which includes radio, infrared, ultraviolet, X-rays, and gamma rays.

I could go on and on (and on and on, believe me) about this. But in general, the type of light emitted by an object tell you a lot about its temperature. Cold objects (like clouds of dust in space, or the ice balls way out past Pluto) give off radio or infrared light, warmer objects like the Sun give off visible light, and very hot objects emit UV, X-ray, or gamma rays. I am way oversimplifying here, but you get the point.

In 2003, NASA launched the last of its “Great Observatories”, a telescope called Spitzer which observes objects in infrared light. Int he past couple of years it’s done some amazing science.

The latest release by the Spitzer folks is a dramatic image of our little sister in the sky, the Andromeda Galaxy. It’s a nearly edge-on spiral, about 3 million light years away (yet still visible as a smudge in the sky… actually, as a I write this, it’s up right now). Like our Milky Way, it’s got lots of stars, as well as lots of dust.

Interstellar dust is dark in visible light. There’s enough of it in Andromeda to absorb the light behind it, so when you look at a visible picture, you see long streamers of dark dust.

But the dust is warm– well, warm meaning about 100 Kelvin (about -170 C). That means it glows in infrared! That makes a pretty different picture of Andromeda taken by Spitzer. Those two images I posted at the top of this entry are of Andromeda. The top one is in visible light, and the bottom is by Spitzer in IR. Take a minute to compare them…

They look really different, don’t they! The dust lanes are dark in the visible picture, but bright in the IR. Below, I enlarged the right side of the images, and you can actually see how the stuff that’s dark in the top picture is bright on the bottom, like a negative!

Images like these will give astronomers all manner of insight into dust in Andromeda, which in turn can tell them the mass of the galaxy, how stars formed (and continue to form) there, and quite a lot else. That also helps us understand our own Milky Way, which, ironically, is hard to study because of all the dust blocking our view of the really interesting parts, like the Galactic center, and dense star-forming regions. There’s a lot to learn, even in our own neighborhood, and telescopes like Spitzer (and, eventually, the James Webb Space Telescope) open a new window on sky, letting us see the Universe in a whole new light.

One of the best parts about being a major superstar celebrity of skepticism (what? You doubt me? Good!) is that I get to travel to way cool places and give talks about antiscience (and sometimes real science too).

Last week, I trekked to Bozeman Montana to talk about Mars at the Museum of the Rockies. They have an astonishing collection of dinosaur fossils there (as befits a museum whose curator is the guy they based Sam Neil’s character in “Jurassic Park” on).
The Hall of Horns and Teeth is an incredible place, with literally tons of triceratops bones as well as other big menacing beasts.

I ran across this guy while wandering the halls…

which was bad enough (look at those teeth!), but when I went around to the other side and took a picture, I saw this…

… and I swear that twinkle in his eye is hunger. And it followed me as I walked around^*.

I was treated to a fantastic behind-the-scenes tour as well. My host, Molly Ward, made sure I got to see two amazing things. One was the room where they hack away (delicately!) at fossils embedded in stone. I saw a triceratops tibia, T. Rex teeth, a diplodocus (or was it a hadrosaur?) shoulder, and lots of other cool stuff.

It’s funny– you watch movies and see the dinosuars, and you know they’re not real. And you see the bones, and it’s hard to see them as actual animals. But then one of the techs pointed out that the side of a fossil shoulder blade had been gnawed on. Evidently after that dinosaur died, some scavengers took advantage of the free meal. You could see where their teeth had gouged into the bone… and suddenly that bone was not a piece of rock, but the remains of a magnificent creature that walked the Earth a hundred million years ago. The sense of time, of age, came over me, like looking through the wrong end of a telescope.

Then I was taken to a back room where one of the paleontologists was constructing a T. Rex skull from fragments. That was totally cool. He had to use a lot of plaster to replace missing parts, but it was still pretty amazing. The skull was easily four feet long, and full of horrifying teeth. It was sleek, streamlined, and clearly belonged to a beast that was meant to kill. It was not hard at all to imagine that skull sitting on top of a multi-ton carnivore, prowling the Montana riverside for prey. I wish I could have taken pictures of it, but it’s still proprietary work. I feel bad now for stealing that occipital bone, but really Molly should have kept a closer eye on me.

After all that, I had a great time talking to staff about the infection of Intelligent Design (I would sure hate to be a dinosaur exhibit docent right about now with that garbage on the rise), and then I gave my Mars talk to about 150 enthusiastic Montanans.

What a place! I hope to go back, and soon. I need to get my creationist astronomy debunking talk prepared so they’ll invite me back. And this time I’ll make sure I have more time to just stare at the fossils… and imagine trying to run away from a 20 foot high monster that’s all teeth and claw…

^* OK, fine, that hole is actually a nasal/sinus cavity and not his ocular orbit. But still, yikes.

The swath of destruction left by hurricane Katrina is awesome to contemplate. For days, weeks, the news was understandably about the lives lost, the sheer destruction on a broad scale. But as time goes on we start to see things on a more specific level. The amount of help pouring into the Gulf is amazing and wonderful. What I find interesting is that there is so much that it can be targeted. If you have a specific interest, you can help out people involved with it; for example, there are several groups trying to help the animals left homeless after the hurricane. If you’re reading this blog (and you are), you probably have an interest in space and astronomy, and that’s where you come in.

Aaron Price has started a fund for astronomy-minded folks to help devastated planetaria and astronomical societies in the Gulf region. Aaron is a good buddy of mine, an Astronomical Technical Assistant at AAVSO, and one of the triune brains behind Slacker Astronomy. As he says on the fund page,

New Orleans and Louisiana are areas with a rich astronomical heritage, including one of the first observatories built in the United States (Pierre Baron Observatory). Much astronomical equipment was lost in Hurricane Katrina, including two public planetariums. Let’s unite and rebuild the astronomical culture of New Orleans and Southeast Louisiana!!

Aaron is a guy who cares a lot about others, and wants to help. If you do too, click on that link and give what you can.