Hot (and cold) on the heels of my posting the infrared view of the nearby spiral M33, the European Space Agency just published this incredible picture of our other spiral neighbor, M31, the Andromeda Galaxy!

[Click to galactinate.]

Oh my. This is a composite of two orbiting observatory images: the far infrared using Herschel (colored orange), and the X-ray emission using XMM-Newton (blue). There’s so much to see! That’s not surprising, since at 2.5 million light years away, Andromeda is the closest big galaxy to us, and presents itself with loads of detail.

First, shown here is Robert Gendler’s magnificent visible-light image of the galaxy. You can see it’s tilted almost edge-on to us, but you can see the central bulge of old stars, the spiral arms winding out, the dark lanes of dust. This image has roughly the same orientation and border as the big one above, so you can compare them.

The infrared observations trace the presence of cold dust, created when stars are born and when they die. And by cold, I mean cold: much of it is just a few degrees above absolute zero. That dust is opaque in visible light, as you can see in Gendler’s shot. But it glows in infrared! The X-rays, on the other hand, are from incredibly hot gas heated to millions of degrees by neutron stars, black holes, and newly-born massive stars; you can see several individual objects in the galaxy’s core. (more…)

A few years back, astronomers discovered that some distant galaxies were blasting out vast amounts of infrared light, but were very faint in visible light, the kind we see. They termed these objects ULIRGs ("you-lurgs"), for Ultra Luminous Infrared Galaxies. The idea is that these galaxies are forming lots of stars, but there was so much dust choking the region that all the visible light was blocked. However, infrared light can pierce through the dust, so telescopes that detect IR can see them. Due to the physics of the situation, astronomers also figured there must be two populations of these galaxies; the ones they had found, and another that was (very) slightly warmer.

Well, they finally found some from that second group:

I know, they don’t look like much, do they? But you have to realize what you’re seeing here: those circled blobs of light are entire galaxies, with billions of stars, and they’re a staggering 11 billion light years away.

That’s really, really far. The Universe is only 13.7 billion years old, so we’re seeing these galaxies as they were just a few billion years after the entire Universe came into being. Not only that, but the amount of infrared light these galaxies are emitting is truly terrifying: in the infrared alone, they are blasting out a solid trillion times the Sun’s entire energy output.

A trillion! 1,000,000,000,000! That’s a whole lot of energy. And it comes from a whole lot of newborn stars, because these galaxies are cranking out stars at a rate 700 times that of our own Milky Way galaxy! The view inside those galaxies must be breathtaking; imagine being surrounded by the Orion Nebula everywhere you look. Wow.

What cracks me up about this too, is how they found them. The European Space Agency is using the orbiting Herschel Infrared Observatory to take a survey of galaxies in the IR. It’s finding a lot of them; in the picture above every dot you see is an infrared source, most likely a galaxy. And that’s a small section of the sky; on the right is an image of a bigger part of the survey. You need to click it and see it full-res to get a sense of how many freaking galaxies there are out there!

As far as astronomical discoveries go, this is another in a long series of steps needed to understand the Universe. I know that in your daily life this may not affect you much; you have other things on your mind, daily stresses and such. But you know what? While I go about my everyday business, in my mind I’m occupied by all the mundane and gross worries of life just like you are, just like everyone else is. But somewhere back there, in some part of my brain, there is knowledge that sits there… and every now and again, it makes itself known.

We can see galaxies a hundred billion trillion kilometers away! We know that stars are being born there, stars like the Sun, and they’re being born every day! If you were there, the sky would be a riot of red and green gas strewn in sheets and ribbons and shock waves and festooned with brilliant jewel-like stars everywhere you looked!

Those wonders are out there, and they’re real. That makes my life better, just knowing that.

Image credit: ESA/SPIRE/HerMES

- Herschel opens its eye
- Herschel eyes the infrared Southern Cross
- Chaos! Turbulence! Blowouts! Herschel!
- Record-breaking galaxy found at the edge of the Universe

Cassini images of Saturn and its environs never get tiresome. And in fact, they can be downright jolting… like this stunning shot of the icy moon Mimas.

Cassini was 100,000 km (60,000 miles) from the small moon when it captured this moody image. It shows a view we can never get from Earth: a crescent Mimas, with the Sun well off to the side.

The giant crater is called Herschel, and it’s a whopping 130 km (80 miles) across. Whatever hit Mimas eons past was huge, and had it been any bigger, or moving any faster, the moon itself may have shattered. In fact, there’s some thinking that this happens to some smaller bodies in the solar system; they can get hit so hard they do shatter, and if the event isn’t too energetic the pieces can recoalesce, reintegrate. This may be why some asteroids are so low in density; they’re essentially rubble piles, like bags of glass.

Mimas was spared that fate those many, many years ago. What was left was an icy moon with a single brooding eye… reminding us that when we stare into the abyss, sometimes the abyss stares back.

Image credit: NASA/JPL/Space Science Institute

Space is black. I mean, duh, right? But really, it’s black because it’s almost entirely empty, so even with stars scattered around, there’s nothing to light up.

But some parts of space are bright: clouds of gas can be lit up by nearby stars, making them glow. However, just to make things more fun, there can be thicker patches of dust mixed in that block the light from the stars and gas behind them. We see lots of those, they’re pretty common. But there’s yet another "however": that dust only blocks the visible light. In the infrared, that dust should itself glow because it’s warm.

NGC 1999 — seen here in a famous Hubble picture — has all these ingredients. It’s a thick region of gas and dust. Stars are being born in and around it, brightening it with their reflected light (as seen in the image; the star V380 Orionis on the left is lighting up the surrounding space junk) as well as warming it up and making it glow on its own. Even so, the oddly-shaped patch to the right was thought to be an unusually dense blob of dust, blocking the light from gas on the other side of it from us.

A lot of the time those dense spots are where stars are being born, and the only way to see them is in the infrared. So astronomers pointed the European space-based Herschel infrared observatory at it, fully expecting to see the whole thing glowing with perhaps a nascent star forming in the dark blob. But that’s not quite how it worked out…
(more…)

Herschel is a European space-based astronomical observatory. It launched last year, and the first science papers are now being published. Along with those papers, the European Space Agency released a bunch of way cool pictures.

As usual, I could use up a mole of electrons describing them, but one in particular caught my eye:

Egads! Click it to embiggen.
(more…)

Every now and again a new picture from a space telescope comes down the pipe^* that’s a little bit different, a little bit of a step to the left. I think this image counts:

Kewwwwl. That’s the Rosette Nebula as seen by the Herschel far infrared observatory. The Rosette is a huge star forming region, and one that’s been around a while. In optical images its name is obvious; it resembles a huge flower in space. The central region looks empty, and that’s because it mainly is: fierce winds from newborn stars have excavated a giant bubble in the center of the nebula. Acting like a snowplow, they have pushed the material from the middle of the gas cloud out to the edges, where it piles up.
(more…)

Of all the moons in the solar system, Mimas is one of the most recognizable. And new pictures from Cassini show us again just why.

On Saturday, February 13, the Saturn probe dipped low over Mimas, sliding past the small moon at a distance of just 15,000 kilometers (9000 miles). For comparison, the Earth is about 13,000 km (8000 miles) across, so Cassini really threaded the needle with this pass.

On its way out from the encounter, when it was about 70,000 km (44,000 miles) from the moon, it snapped this astonishing shot:

Yegads. Note that this image is raw and unprocessed — it’s basically straight off the camera (and converted to JPG). But holy cow, there’s a lot to see. The giant crater Herschel is pretty obvious. It’s about 130 km (80 miles) across (compare that to Mimas itself, which is 400 km in diameter!), with a central peak characteristic of large impact basins. I think that’s where the main weapon is located.

Mimas has clearly had an interesting past: it’s battered beyond belief, loaded with impact craters. In fact, one thing scientists hope to learn from this pass of the moon is a bit of its timeline. By counting up the number of craters inside Herschel, and comparing that to the crater counts outside of it, they can estimate its age. Fewer craters inside of Herschel means it’s younger than the surrounding surface, for example. But how much younger? Maybe we’ll soon know. And they’ll be able to see craters that are pretty small; the resolution in the image here is about 200 meters (1/8 mile) per pixel. That’s about the same as we can do on our own Moon from Earth!

Sometimes with raw images like this, the background can be a little screwed up due to artifacts in the camera. But in this case, the glow on the left hand side of the big image is quite real: it’s the face of Saturn itself! The geometry of the shot was just right to capture a bit of the cloudtops of the ringed world. Very cool.

These are gorgeous pictures, and it’ll be nice to see them once they’re completely processed, too. We’ll learn a lot about the moon from them… and as far as Mimas goes, I just hope it’s not fully armed and operational. I suppose I shouldn’t be too worried though. After all, I used to bullseye womp rats in my T-16 telescope, and they’re not too much bigger than Mimas.

Image credit: NASA/JPL/Space Science Institute