Hey, it’s been a while since I posted a really pretty deep space picture just for the heck of it. So here you go: the magnificent spiral galaxy NGC 4945:
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| NGC 4945. Image Credit: ESO. Click to embiggenatrify. |
Wow. This image was taken using the European Southern Observatory’s 2.2-meter MPG/ESO telescope in La Silla, Chile. The picture uses five filters: three to mimic what the eye sees (red, green, and blue) plus two more which let through light emitted by hydrogen and sulfur. Those last two filters emphasize light given off in giant gas clouds that are actively forming stars. You can see that in the image as the streaks of pinkish light around the edge of the galaxy.
But there’s more going on here than meets the eye…
NGC 4945 is about 13 million light years away in the constellation of Centaurus. All the stars you see in the image are in our own Milky Way galaxy; it’s a little bit like looking through a dirty window at an object outside. Looking in this direction means looking right through a local spiral arm of the Milky Way, so we see lots of foreground stars interfering with our view… but it makes the image prettier.
This galaxy is an interesting one to study. First, it’s a lot like the Milky Way, a spiral galaxy with hundreds of billions of stars. Second, it’s close to us, making it easy to study. We have a great view of it! To give you a sense of scale, the full Moon would just fit in this image, so we really can see very fine detail in the galaxy. In fact, a search of the professional journal papers indicates it’s one of the most studied galaxies in the sky.
Even better, NGC 4945 is an active galaxy, meaning it’s shooting high-energy light and matter out of its nucleus. You can’t tell in this picture because there are thousands of light years of gas and dust inside the galaxy blocking our visible-light view of the center. But X-rays, for example, slice right through all that junk, and in fact NGC 4945 is one of the brightest extragalactic X-ray sources in the sky. Even cooler, radio observations of the core of the galaxy reveal it has a ring of intense star formation occurring just 160 light years from the galactic nucleus!
That’s incredible, because the fact that NGC 4945 is active means it has a supermassive black hole at its core which is busily gobbling down matter at an atrocious rate. It doesn’t seem at first blush like the best environment to make new stars… but you need to drill down a bit here. Matter spiraling down into a black hole heats up monstrously due to friction, magnetism, and other forces, and a wind of subatomic particles can blast out from the material. If there is an abundance of gas and dust near the center of the galaxy — and radio observations indicate there is — then this wind slams into that material, compressing and collapsing it, forming stars.
Think for a moment on that: in the deepest hearts of galaxies, sometimes the place where matter goes to die — and directly because that matter is disappearing for ostensibly forever — is also where new stars are born.
I don’t believe there is a driving force to this Universe, no guidance or hand at the wheel… but it still gets to me sometimes, just how poetic a cosmos it is that we live in.
September 2nd, 2009 at 11:48 am
Beautiful…
What’s the little smudge in the top-right corner? Is that a Magellanic-Cloud-style cluster near NGC4945, or a more distant galaxy?
September 2nd, 2009 at 12:16 pm
The more I look at the picture and think about “star pollution” the more it makes me laugh.
September 2nd, 2009 at 12:18 pm
Amazing. I admit I’m still moved by the concept that what we’re seeing happened 13 million years ago. Not that you can ever directly grasp the scale of things but, you know…
September 2nd, 2009 at 12:23 pm
An AGN in the neighborhood! How convenient! I wonder if this’d count as a quasar if it was farther away. Lots to study here.
See you all tomorrow night at the benefit star party in Atlanta!
September 2nd, 2009 at 12:42 pm
Awesome post!
September 2nd, 2009 at 12:54 pm
“To give you a sense of scale, the full Moon would just fit in this image, so we really can see very fine detail in the galaxy.”
The sense of scale is is awesome, and still a little confusing. But I think I know why. My instant reaction was that if the moon would just fit in that image one should be able to see this galaxy with the naked eye. However the intensity of the moon’s light would be some orders of magnitude greater than such a distant object so the imaged intensity of this galaxy must be the result of an incredibly long exposure? Is this correct? Any other comments on its scale? The notion that all of the stars pictured are also in our local galaxy is also amazing.
September 2nd, 2009 at 1:05 pm
You say “All the stars you see in the image are in our own Milky Way galaxy.”.. .it would be clearer and more accurate to say, “All the individual stars you see in the image are in our own Milky Way galaxy.”
September 2nd, 2009 at 1:20 pm
Durn foreground stars…in the way of the purty galaxy!
Could someone call the Vogons?
September 2nd, 2009 at 1:21 pm
The question is: Is it our Galactic Evil Twin? Quick, look for a goatee on that galaxy!
September 2nd, 2009 at 1:30 pm
raaaaaaaaaaaad.
September 2nd, 2009 at 1:55 pm
@ #6. Arnold Martin
Yes, this image would have been composed from a stack of many seperate images of different exposures.
If you want an example of a galaxy that you can fairly easily see with the naked eye (if you’re in a dark sky area) then take a look at the Andromeda Galaxy (M31). To the naked eye, it will appear as a faint smudge of light. Through binoculars, you’ll see a slightly brighter faint smudge of light. Even in only reasonably dark skies, you can see it faintly through binoculars, but naked eye would be difficult unless you know where to look.
In the U.S., you can find M31 in the Eastern sky, probably about 1/3 to 1/2 of the way up the horizon, any time after sunset. It’s about as high as Jupiter is right now, just more eastward.
September 2nd, 2009 at 1:56 pm
This is probably a really stupid question, so I apologize in advance.
One always hears about how images from telescopes are taken with “filters” to “simulate” what we see with our eyes. What nobody ever explains is why that is necessary. Why can’t they just “take a picture” the way any other camera would, just with an exceptionally powerful zoom lens?
I understand that these telescopes take in more than just what our eyes can see, and this is useful for studying different aspects of astronomy, but it seems like most of these observatories (especially hubble) have many different instruments and cameras, so why not one that is purely an optical camera?
Then there would be no doctoring of images necessary, no false color…you’d see the stars for what they are (or at least the tiny fraction of them that we “see” with our eyes).
Like I said, maybe this is a stupid question. I always assumed the answer was “optical astronomy doesn’t teach us anything new, so we don’t waste money and space on standard cameras when we can send more important equipment instead.”
September 2nd, 2009 at 2:18 pm
@Matt – “Why can’t they just “take a picture” the way any other camera would, just with an exceptionally powerful zoom lens?”
Here you go:
http://www.youtube.com/watch?v=ueIYOP7LN8c
September 2nd, 2009 at 2:30 pm
@ Matt:
You answered your own question, sort of. “You’d see the stars for what they are…”
It’s not that “visible” light is so bad, it’s just that it’s such a wee small part of the electromagnetic spectrum.
Astronomical objects emit radiation all along the spectrum, and there’s information to be learned from looking at as much of it as we can. Different wavelengths will tell you different things about the object you’re studying.
Also, different wavelengths of light behave differently. Infrared, for example, which is a lot longer wavelength than visible light, can quite easily penetrate thick dust clouds which would be otherwise opaque. Thus we can see “inside” these clouds or behind them.
BTW, “false color” isn’t an artistic choice. Assigning easily distinguishable color to a wavelength of light we couldn’t otherwise see is just a way of being able to more easily assess the data. The color choices themselves are often arbitrary, but the information they convey is integral to the object being studied.
All that being said, there’s still a lot that can be learned from visible light images. The human brain has an amazing analytical capacity. Sometimes just getting a really clear picture we can “see” can lead to astounding leaps of intuition and discovery.
September 2nd, 2009 at 3:16 pm
Finally! Someone else puts it in the right terms – “How poetic the cosmos is..”. And we’re learning all this from nothing but ‘light and shadow’. What’s even more mindboggling is that something that ‘came out of a black hole’ (yeah yeah [sic] as much as you want
) like that is capable of looking at something else, and _thinking_ about the whole process.
September 2nd, 2009 at 5:36 pm
Woah. That’s gotta be photoshopped. LOLL
September 2nd, 2009 at 5:41 pm
To give you a sense of scale, the full Moon would just fit in this image, so we really can see very fine detail in the galaxy.
I’m a little confused too. Does this mean that if it was bright enough to see with the naked eye it would cover as much sky as the full moon? If so, holy smoke.
September 2nd, 2009 at 6:58 pm
In a good set of binocs and with a dark night you can make out the Andromeda galaxy across nearly 4° of sky, or about 8 times the diameter of the full moon. That’s a serious whoa.
September 2nd, 2009 at 7:04 pm
To give you a sense of scale, the full Moon would just fit in this image, so we really can see very fine detail in the galaxy.
The Angular Diameter of the Moon* is 29.3 to 34.1 arcminutes; the Major Diameter of NGC 4945 is 20.0 arcminutes and the Minor Diameter is 3.8 arcminutes.
So, if NGC 4945 was bright enough to see with the naked eye, it would appear about 2/3 the diameter of the Full Moon.
*Source: Wikipedia — Moon.
September 2nd, 2009 at 7:17 pm
Came across this video while looking up the one suggested by Caleb Jones (#13), and it’s also a great illustrator of why visible light isn’t as useful or interesting by switching back and forth between the two, allowing you to see inside concealing clouds of dust. Great stuff.
http://www.youtube.com/watch?v=Rm3Sj8qAaWg&feature=channel
September 2nd, 2009 at 8:25 pm
finally. some astronomy.
September 2nd, 2009 at 8:29 pm
@ Matt:
The other reason they use filters is that the vast majority of “ordinary” digital cameras use colored filters (red, green, blue) alternating over the pixels – the “picture elements” themselves are actually monochromatic – the camera’s software then blends it all together for the final image that you see. But this sacrifices some image detail since you are only using 1/3 of the available pixels in the sensor for each color, then the camera averages it all together. That’s the main reason why more megapixels is better.
By imaging astronomical objects using separate filters placed over a monochromatic imaging sensor, astronomers get more detail in the images since ALL the pixels in the sensor are available for each wavelength. Obviously it takes longer to expose since it has to be done for each filter, instead of all at once, then an imaging specialist will blend it all together in software back at the computer lab to create the final amazing image BA shares with us.
September 2nd, 2009 at 8:47 pm
Ivan ( post 21(not ivan3man)), what, the ISS isn’t related to astronomy? Fires threatening to consume an observatory aren’t astronomy related? 118th carnival of space not related to astronomy?
September 2nd, 2009 at 8:50 pm
Thanks.
I was hoping to point the ol’ Galileoscope at Andromeda but it may be too low in the sky for us Southern Hemispheroids. I’ll just have to make do with the Magellanic clouds.
September 2nd, 2009 at 9:15 pm
@ Shane:
Mind you don’t fall off the planet while you’re messing around down there.
Seriously, tho. Way jealous at being able to see the Magellanic Clouds. Omega Centauri, I should think, would also be a good target for that Galileoscope.
September 3rd, 2009 at 12:06 am
Does that mean I have a doppelganger in that Galaxy? ‘Cause that would be scary!
September 3rd, 2009 at 5:49 am
I’ve always enjoyed photos of galaxies with lots of foreground stars. I get a much greater sensation of looking “out” at the object. I’m not as aware of that at the eyepiece, since these images go much fainter – and hence more stars – than you get visually.
I also find it interesting that even if we could get closer, it would still not look the way it does in images. Think about the Milky Way. That’s what galaxies look like up close.
September 3rd, 2009 at 9:27 am
Phil
I enjoy your site and blog, and have always had a fascination with Astronomy and science in general.
And yet, I am a firm believer in the Bible and God and Jesus Christ. I admit I do not have all the answers of how to reconcile the Bible and its accounts with what our observations of the Universe indicate with its age etc.
You look at the universe and say, Wow look how beautiful and awesome everything turned out.
Yet I look at the universe and think, “How can you see such an incredibly complex, (and moreso the more we learn) Universe and not see that it was supremely designed?
Do I think the universe is 6,000 years old? 14billion years (or so). I am not sure.
I do believe it was Created by God, all of it, regardless of how or when he did it.
(I could talk on this for awhile, but this is a comment section, not an essay).
September 3rd, 2009 at 10:29 am
I was surprised to learn that nearby galaxies are so large in the sky. I always assumed they were too far away.
Thinking about NGC 4945…
If I start with knowing how big it must be, then I am amazed how far it must be from us.
If I start with knowing how far away it is, I am amazed how big it must be.
September 3rd, 2009 at 10:58 am
@ Jason,
Two words: Creation myth.
Hint: Click the link and scroll down — it’s a bloody long list!
September 3rd, 2009 at 12:09 pm
28. Jason Says:
September 3rd, 2009 at 9:27 am
You look at the universe and say, Wow look how beautiful and awesome everything turned out.
Yet I look at the universe and think, “How can you see such an incredibly complex, (and moreso the more we learn) Universe and not see that it was supremely designed?
___________
Simple. Because there is no evidence that it was supremely designed. In fact, there’s no evidence of design, period.
These things like stars and galaxies and nebulae are not inherently beautiful. In fact, they’re quite ugly and frightening up close.
Stars are giant balls of plasma that put out all sorts of harmful and deadly radiation. Galaxies are collections of stars orbiting supermassive blackholes that could, according to the Drake equation, be massacring thousands if not millions of civilizations as they suck the life out of stars near the hub. Nebulae are huge inhospitable clouds of poisonous gases and dust left over from the violent and cataclysmic death of a star.
They’re only beautiful because our human eyes like colors, and because our human brains like patterns and order and recognizable shapes. That’s not evidence of design, that’s evidence of interpretation.
Quite simply, there is no evidence that the universe or our solar system or life on Earth was designed in any way. There’s plenty of evidence that these things arrived at their present state due to natural forces, but no evidence of design. In fact, there’s no evidence that it was created.
September 3rd, 2009 at 12:52 pm
@toasterhead,
I’d add that, in much the same way that a gambler might “forget” his fifty losing hands, look at his ten winning hands, and conclude that the night went very well, we “forget” about all the deadly/dangerous aspects of the universe and focus on the “pretty” aspects of it. So, yes, the universe is a very beautiful place. But don’t let it fool you into thinking it’s all rainbows and unicorns, because the universe is also a very deadly place also.
September 3rd, 2009 at 1:17 pm
31. TechyDad Says:
September 3rd, 2009 at 12:52 pm
But don’t let it fool you into thinking it’s all rainbows and unicorns, because the universe is also a very deadly place also.
Pfff don’t even get me started on unicorns. Vicious little buggers, they are…
September 3rd, 2009 at 1:51 pm
Of course the universe is a dangerous and Deadly place, I never suggested it wasn’t, nor did I suggest the beauty and intricate design was all “rainbows and Unicorns”
In fact I could point out that this only enhances my argument. Look at all the conditions that must balance just right to make life here not only possible, but enjoyable.
–The counter argument is that life evolved here so naturally we find it the best environment. If we had evolved on Titan we would say the same thing about it.
In the end, I take it as a matter of faith. As must you for your view. I cannot provide “concrete irrefutable proof” that God is the creator and architect. But neither can you prove that an infinite being did not create and direct the universe.
I do see each discovery, each new thing Humanity learns as expanding our knowledge and Understanding of this wonderous creation.
September 3rd, 2009 at 2:50 pm
33. Jason Says:
September 3rd, 2009 at 1:51 pm
In the end, I take it as a matter of faith. As must you for your view. I cannot provide “concrete irrefutable proof” that God is the creator and architect. But neither can you prove that an infinite being did not create and direct the universe.
________________
I cannot prove a negative, no. You are right. But if there is a creator and architect to the universe, what did he/she create, exactly? How is he/she directing it, exactly?
He/she didn’t create stars and planets. We can see them forming in nebulas in our own galaxy by natural forces, so we can conclude that there is no outside force that forms stars and planets. He/she didn’t create galaxies, because we can see them in the deep field Hubble images and see them forming naturally due to gravitational and electromagnetic forces. We can even see the background radiation from before the energy of the universe had settled down into matter, and there are no patterns that indicate the hand of a designer.
And it becomes even fuzzier if we start thinking about God the director. The events that happen in the universe around us all seem to happen as predicted due to the forces we can measure. When stars run out of fuel, they collapse or go nova, depending on their size and composition. Expansion pulls galaxies away from each other, unless they’re close enough and gravity pulls them toward each other. On the whole, stuff out there behaves the way it should. God is either an extremely neurotic micromanager or a very hands-off director. Sure, there are still plenty of mysteries, but do you really want to plug God into those gaps as a holy placeholder?
All that’s really left is the constants. You can believe that God said “Let There Be Light, and Let Its Velocity Be 299,792,458 Meters Per Second In A Vacuum.” But why? Is that the optimal speed for light to travel? Is it the most likely to produce life? Is it just random, or chosen on a whim? Is it an experiment – will the next universe have a speed of light of 299,792,459 m/s, and so on?
Ultimately, it’s a philosophical question, and the answer depends on what you want your God to be. You’re welcome to see him/her as you please. Personally, I don’t want my God to be a neurotic director or an experimenting cosmologician or that vindictive jerk from the Old Testament.
September 3rd, 2009 at 7:33 pm
@mark
im mostly talking about all the antivax and skeptic articles.
September 3rd, 2009 at 8:47 pm
@Ivan
http://blogs.discovermagazine.com/badastronomy/2007/07/15/politics-science-me-and-thee/
September 4th, 2009 at 8:50 am
@Ivan,
What shane said. Also, it’s a bit like the TV; if you don’t like what’s on the channel, you can change the channel or turn it off. I don’t know of anyone having a gun held to their head to visit here.