The dark night rises?
[Click to stimulatedemissionate.]
Nope. This way cool picture is actually the Very Large Telescope observatory in Chile, though that really is a laser being shot into the sky. Our atmosphere boils and writhes, distorting the view of the stars. There’s a layer of sodium atoms in the atmosphere far above the ground, and the laser is designed to make them glow. This creates a very bright point-like source of light that the telescope can view, and measure in real time how the atmosphere is messing up the observation. This can then be compensated using very fast computers and adjustable mirrors, and the result is a far sharper image than could be obtained otherwise.
During this 30 minute exposure, the Earth rotated enough to trail the stars, and the laser was moved to stay on target. That’s why the stars are curves, and the normally pencil-thin laser looks like it does. It makes for a pretty slick effect! Shorter exposures are pretty amazing, too, and I have several linked in the Related Posts section below for your amusement.
Image credit: ESO/J. Girard
We live in the outskirts of our disk-shaped galaxy, our Sun and planets located about halfway from the center to the edge. This is a bit like living a few kilometers away from a city, in the suburbs. From that distance, when you look toward the city, you see more buildings, more activity, just more stuff going on.
The same thing is true for us on Earth: the center of the galaxy (downtown) is located toward the constellations of Sagittarius and Scorpius, so when we look in that direction there’s lots of fun things to see: more stars, more gas and dust, more clusters, more stellar nurseries.
And when you point the monster Very Large Telescopes ginormous 8 meter mirror in that direction you can see amazing details in that buzzing hubbub, like this lovely shot of the nebula NGC 6357:
[Click to ennebulanate, or grab the 3760 x 1560 pixel version. note: I rotated the image to make it fit the blog better and so you can see it more properly embiggened here.]
This piece is actually part of a much larger complex of gas and dust, but shows some nice features. The whole place is lousy with hydrogen gas, glowing rosy red due to energy pumped into it from young, massive, hot stars. Those stars are forming from that very gas, so they’re lighting up their own nursery. Running right through the middle is a river of interstellar dust – not like the dust bunnies under your bed, this is actually more like soot, and made up of complex clumps of organic molecules. This dust absorbs and blocks light behind it, so it looks like it’s splitting the gas cloud in half.
You can also see some structures in the dust, like the "fingers" of material at the top pointing to the center of the gas. Those are actually dense clumps of material being slowly blasted away by the fierce, intense ultraviolet light from newborn stars. Think of them like sandbars in a river getting eaten away by the current. They point right at the stars doing the deed, a cosmic "j’accuse!"
Nebulae like this are among my favorite objects in the sky. They’re beautiful, they’re fascinating, and it’s more than a little mind-blowing to know that there are dozens, hundreds, maybe thousands of stars being born in these objects even as we watch. And it also gives me a bit of a shiver to know that these objects are ephemeral, too: the stars being born really are slowly eating away at the material… and many of these stars will explode as supernovae someday, and that destruction won’t be slow anymore! The onslaught of high-energy radiation and material moving outwards from those stellar blasts at thousands of kilometers per second will make short work of this nebula. So take a look while you can. In a million years or four, this whole thing will be gone.
[The Desktop Project is my way of forcing myself to write a post about the astronomical images I've been saving to my computer's desktop and then ignoring. I've been posting one every day for nearly a month, and this, my friends, is it. The last one. And I saved it for this occasion, because it's ridiculously awesome. Thanks for bearing with me as I did this bit of housecleaning.]
The constellation Carina is a mess. It represents the keel of a ship, but in the sky it happens to be in the direction of the disk of our galaxy, which is like having a window in a building facing downtown in a busy city. And like an urban center, the Milky Way in that direction is lousy with gas, dust, stars… and much of this is chaotic, disturbed, and, well, messy.
Oh, but what a glorious, glorious mess. Behold! The Carina Nebula!
[Click to ennebulenate, or grab this ridiculously huge 13,000 x 9000 pixel monster version. And yes, you very, very much want to make this bigger.]
Holy wow! I love this image! It’s got it all: stars of every color studding a riotous background of gas, itself glowing red or reflecting blue, silhouetted in great ostentatious sweeps of dust. Shock waves riddle the gas, compressing it here and there in arc, loops, streamers, and filaments.
It’s ridiculous, and spectacular.
The image was taken using the HAWK-1 detector on the European Southern Observatory’s Very Large Telescope. This is an infrared picture, using colors outside what the human eye can detect. In the picture, what you see as blue is actually light at 1.25 microns, green at 1.65, and red at 2.2 microns. For comparison, the reddest color the eye can see is about 0.7 microns. Amazingly, in visible light this region is even more chaotic looking.
The Carina Nebula is about 7500 light years away, and is the site of a lot of star formation. Many of the stars being born are very massive, which makes them hot, blue, and frighteningly luminous. See that bright star in the lower left? That’s Eta Carina, one of the most massive stars in the galaxy. To give you an idea of how stupid violent and unstable that star is, in 1843 it erupted in an explosive event that rivaled a supernova. The star held together, barely, but it ejected two lobes of matter that have about as much mass as the Sun. Each. And they’re expanding at 700 km/sec (400 miles per second), fast enough to cross the continental United States in 12 seconds.
And one day Eta Car will explode. It’s too far away to hurt us, but what a sight that’ll be! And even now, just sitting there not exploding, it still shines about 4 million times brighter than the Sun. Four million. If the Earth were as close to Eta Car as we are to the Sun, we’d be vaporized into an ionized memory.
The HAWK-1 image is actually high enough resolution to get a lot of detail. Here’s a collection of nine interesting regions:
In what has become an annual tradition here at BA Central, literally the day I post my gallery of best pictures of the year, something comes along that really would’ve made it in had I seen it even a few hours earlier. In this case, it’s a combined Chandra X-Ray Observatory and optical Very Large Telescope image of galaxy clusters colliding that’s so weird that at first I thought for sure it was Photoshopped! But it’s real, so check this out:
What you’re looking at is a collision on a massive scale: not just two galaxies, but two clusters of galaxies slamming into each other, forming this object, called Abell 2052. The total mass of this combined cluster is almost beyond imagining: something like a quadrillion times the mass of the Sun — 1,000,000,000,000,000 Suns! Note that our galaxy has about a hundred billion stars in it, so Abell 2052 is about 10,000 more massive. Yikes.
Sometimes I think it’s a good idea to start off the week with a gorgeous spiral galaxy. So here’s a fantastic example of a flocculent (fluffy or patchy) spiral: NGC 3521 in the constellation of Leo, care of the Very Large Telescope:
[Click to enflocculenate.]
NGC 3521 is a mere 35 million light years away (350 quintillion kilometers, a comfy airplane ride of just 50 trillion years or so; ask for an extra bag of peanuts), which is outside our local area but still close as the Universe goes. It’s half the size of our Milky Way home, about 50,000 light years across. [Note that it has that same effect I mentioned in an earlier post where the dust on the side of the galaxy closer to us appears darker; the light from intervening stars in that galaxy appear to "fill in" the dust on the other side.]
A large fraction of spiral galaxies have these patchy, ill-defined arms, so nature is telling us something: these things are easy to make. Grand design spirals — ones like ours, with splashy well-defined spiral arms — appear to be due to some global effect creating the arms; stars near the galaxy’s center orbit more quickly than ones farther out, so spiral arms should get wound up relative quickly. The fact that so many grand design spirals are seen means that this differential rotation does not destroy the spiral pattern: something most be maintaining it (we think it’s a traffic jam-like effect).
Flocculent spirals, on the other hand (arm?) are more likely to have some sort of local effect in the disk creating the patchiness — if it were some galaxy-spanning effect then we’d see better defined arms! Perhaps regions of local star formation from dense clouds are being stretched and pulled apart by differential rotation, for example, or, rather more likely, combination of several factors working in concert.
But the contrast between the two types of spirals is striking. And the differences between spirals don’t stop there: there are barred spirals, ones with small nuclei, ones with big nuclei, arms that are wound tightly, others loosely… the variety in nature on how to make a colossal structure 500 quadrillion kilometers across containing hundreds of billions of stars is pretty amazing. And we have a long way to go to understanding why they’re different! The math and physics of the behavior of galaxies is fierce, to say the least. They may look fluffy, but the science underlying them is anything but.
Image credit: ESO/O. Maliy
One of the basic principles of modern science is that the physics we understand here, on Earth, work everywhere. This turns out to be a pretty good assumption, because we see it coming true time and again. That knowledge can then be used to figure out things that are happening at very large distances — even well across the Universe.
With that in mind, I present to you LAB-1: a glowing glob of gas as seen by the European Southern Observatory’s Very Large Telescope:
[Click to, um, englobenate.]
This, however, is no ordinary Space Blob: it’s located at the staggering distance of 11.5 billion light years from Earth! Not very many objects have been seen farther away than this, and it’s one of the single biggest discrete structures seen this far away. It’s about 300,000 light years across — three quintillion kilometers, or three times the diameter of our own galaxy. That’s pretty flipping big.
And although it’s faint to our telescopes, at that distance it must actually be tremendously luminous for us to see it at all. Something is making it glow fiercely, but what? One hint is in the cloud’s name: the LAB in LAB-1 stands for Lyman Alpha Blob. Lyman Alpha (written as Lyman-α) is a specific color of light you get from hot hydrogen gas (just so’s you know, it’s emitted when the electron in a hydrogen atom jumps down from the second to the lowest orbital energy state). Normally, Lyman-α is in the ultraviolet, but this blob is so far away the light is shifted by the expanding Universe into the optical region — that’s why it looks green in the image above.
It takes a goodly amount of energy to create Lyman-α light, so something big is going on here. Maybe this gas cloud is collapsing under its own gravity, and is heated up. Or maybe there are big galaxies inside of it, causing it to glow. How can we tell which is the culprit?
It turns out there is a way: polarization.
The largest structures in the Universe are superclusters: not just clusters of galaxies, but clusters of clusters. They can stretch for millions of light years and be composed of thousands of galaxies.
Abell 2744, at a distance from Earth of about 3.5 billion light years, is one such megastructure (if you want to sound fancy, astronomers call it "large-scale structure"). Astronomers have been studying Abell 2744 with an arsenal of telescopes, and have discovered that it’s actually the result of the ongoing collision of four galaxies clusters. If you’ve ever wondered what 400 trillion solar masses of material slamming into each other looks like, well, it’s more than a bit of a mess:
[Click to enclusternate.]
Yeah, like I said, it’s a mess.
First off, this picture is a combination of observations from Hubble (in visible light, colored blue, green, and red), the Very Large Telescope (also blue, green, and red), and the Chandra X-Ray Observatory (X-rays, colored pinkish). In visible light you can see literally hundreds of galaxies, probably more, dotting the supercluster. The pink glow is from very hot gas between galaxies; it started its life as gas inside of galaxies that got stripped off and heated to millions of degrees as the galaxies plow through the space around them (I like to think of it as opening a car window to let a noxious smell out — the wind from the car’s motion pushes the air inside the car out the windows).
The blue glow is perhaps the most interesting bit here: it’s a map of the location of dark matter. This type of exotic matter neither emits nor reflects light — hence the name — but it has mass, and that means it has gravity. As I described when this method was used to trace dark matter in the Bullet Cluster, gravity bends space, and light follows that curve. Galaxies farther away get their light distorted by the gravity from dark matter, and that distortion can be measured and used to trace the location of dark matter. The blue glow in the image above maps that.
The thing about dark matter is that it doesn’t interact with normal matter (electron, protons, you, me, lip balm, oranges, whatever). But all that gas between galaxies shown in pink is normal matter, so when one galaxy cluster slams into another at a few thousand kilometers per second that gas gets compressed, mixed-up, and heated. But dark matter just blows right on through. So by comparing the location of the galaxies, the dark matter, and the hot gas, a lot of the cluster’s history can be unraveled.
For one of the brightest stars in the sky, Betelgeuse still has some surprises up its sleeve. We’ve known for a couple of years it’s surrounded by a cloud of gas, but new observations show that nebula is far larger than previously thought!
[Click to enorionate.]
This new image is care of the Very Large Telescope, and shows a very deep and very high-resolution shot of Betelgeuse in the infrared. The inner black circle is the 2009 shot of the star and its surrounding gas — what we knew about before — and the big image shows all the gas around it just discovered. At the very center is a red circle indicating the actual size of Betelgeuse on this scale — it’s a red supergiant, and nearly two billion kilometers in diameter.
This structure is actually a wind of material blown off of the star itself. The exact mechanism behind this is unclear, though. Red supergiants are so big that gravity on their "surface" (they don’t really have a surface; they just kinda fade away into space) is very weak, and they can barely hold on to the material there. They are also incredibly luminous — Betelgeuse is 6000 trillion kilometers away, yet one of the brightest stars in the sky — so much so that the pressure of light is very strong. This pressure can lift material off the surface and blow it into space. It’s also known that Betelgeuse has gigantic convection cells bringing hot material from deep below up to the surface, and that’s part of this process as well.
Once the material is ejected it forms into dust grains: complex molecules including hydrocarbons. The astronomers doing this observation detected oxygen-rich dust in this nebula (PDF), which given the environment is most likely silica or alumina. Silica, also known as silicon dioxide, is the main constituent of sand and quartz! That’s the most common constituent in the Earth’s crust — over 60% by mass — and we think that a lot of the materials in the Earth’s crust actually formed in the winds of red giants and supergiants.
Think about that the next time you’re playing at a beach this summer. Billions of years ago, some now long-dead red star belched silicon dioxide into space, seeding a nearby nebula with materials… and this cloud collapsed to form our Sun and planets, with some of that interstellar silicon dioxide making up the sand under your feet.
Not to mention that a lot of that water you see in the ocean came from giant comets slamming into the Earth shortly after it formed. Does that make your heart pound, your blood race? Because the iron in your hemoglobin came from massive stars that exploded long ago. If that makes you smile, why, the calcium in your teeth most likely came from an entirely different kind of star that exploded eons ago as well.
We’re directly tied to stars like Betelgeuse.
And oh: while you’re at the beach, do me one more favor. Find a grain of sand, just a single grain about a millimeter on a side. Now give it to a friend, placing it on their outstretched finger. Walk about 40 meters away, turn around, and look at your friend. The grain of sand will be invisible to your eye, far too small to see. Yet at that distance, that grain of sand appears to be the same size as the entire image above of Betelgeuse.
And you thought you were just going to the beach.
Someday, Betelgeuse too will explode as a supernova. It will briefly become as bright as the Moon, then fade over months. The material we see here will get slammed by octillions of tons of gas moving outward 10,000 times faster than a rifle bullet, destroying it. And when it’s all done, our familiar constellation of Orion will be left without his right shoulder.
But it’s worth it. What planets will coaleasce, what suns will shine, what forms of life will one day arise from that material, and wonder which star it was to which they owe their existence?
Image credit: ESO/P. Kervella
Oh, what the heck. After posting the video earlier showing the Earth rotating around the sky, I might as well show you the original video, since it really is so beautiful. This time lapse shows the sky spinning over the Very Large Telescope observatory in Chile, one of the finest observatories in one of the darkest sites on the planet.
[Set the resolution to 720p to see it properly unenpixelated.]
A couple of things I want to point out: at 1:10 into the video, you see the Milky Way rising majestically over the mountains, and you can see a faint, whitish glow stretching diagonally across the field of view, at an angle to the galaxy. That’s called the zodiacal light, and is caused by the reflection of sunlight by dust in the plane of our solar system. It’s probably due to eons of collisions grinding asteroids into dust; they tend to orbit the Sun in the same plane as the planets. It’s actually a disk of dust, but since we’re in it, we see it as a line across the sky. It’s pretty faint, and you need dark skies to spot it.
I also love the shots of the observatories shooting orange lasers out their domes (here’s a gorgeous hi-res photo of it). They’re
fending off attacks by the Goa’uld, Ori, and Wraith using those to help counteract atmospheric distortion; the laser hits a layer of sodium atoms high in the atmosphere and causes them to glow. This creates a bright artificial star in the telescope’s view, which jiggles and wiggles as the atmosphere roils. The way the "star" moves can be counteracted by the telescope, sharpening up the image it makes. This tech, called adaptive optics, has revolutionized high-resolution ground-based astronomy. It has also given the VLT the ability to make incredibly sharp and gorgeous images; see for yourself.
Don’t forget to watch the companion video to this, too. It’ll change your perspective. Literally.
- Incredibly, impossibly beautiful time lapse video
- Australian Outback time lapse
- Dust, from the desert below to the galaxy above
- Stunning winter sky timelapse video: Sub Zero
- OK, because I like y’all: bonus aurora timelapse video
- Sidereal Motion
- Amazing wide-angle time lapse night sky video
- AWESOME timelapse video: Rapture
Globular clusters are among the most spectacular of objects in the entire night sky. Compact balls of hundreds of thousands of stars, well over a hundred orbit our galaxy at various distances. When viewed by Hubble, the result is nothing less than jaw-dropping:
[Click to embiggen, and please do; I had to crop the image to get it to fit and the full-size version is even more spectacular!]
This view of Terzan 5, as it’s called, is gorgeous! The thing is… Terzan 5 may not really be a globular cluster. Sure, it’s a cluster, and it’s globular, but it may not be what we usually think of as a globular cluster.
When I read the press release for the picture, the name Terzan 5 looked familiar. So I searched my blog, and found I’ve written about this object before. That post was about a ground-based Very Large Telescope picture of the cluster, seen here. The picture looks odd because Terzan 5 lies in a very crowded region of the Milky Way, lousy with dust. That interstellar junk tends to scatter away blue light, making objects look redder. The dust blankets across Terzan 5, but is thicker in one half than the other, making that side redder than the other.
Terzan 5 itself is also unusually dense, with stars packed in it more tightly than is usual for a globular cluster. Not only that, but studies have shown the stars in the cluster appear to fall into two different age groups; one significantly older than the other. That’s weird. Read More