What does a half million galaxies look like?

By Phil Plait | December 10, 2009 7:25 am

What does a half million galaxies look like? Something like this:


Whoa. That’s a part of a huge image just released by the Canada-France-Hawaii Telescope Legacy Survey Deep Field #1, a ginormous mosaic of the night sky… and by ginormous, I mean GINORMOUS. It covers a solid square degree of sky — 5 times the area of the full Moon — and tips the scale at a whopping 370 megapixels! It took 5 years and several hundred hours of observing time with the 3.6 meter telescope on top of Mauna Kea to get this massive mosaic.

The image itself may look cool and all, but the true power comes when you give in to the dark side you use the interactive zoom feature. You can surf the entire mammoth 370 million pixel image, zooming in on galaxies galore. And you won’t run out of objects to investigate any time soon: there are an estimated 500,000 galaxies in the image. Like the Hubble image I posted about yesterday, almost everything you see in the image above is a galaxy, not a star.

The images were taken to look for very distant supernovae. It was the investigation of these far-flung stellar explosions that led astronomers to determine the Universal expansion is accelerating, and to postulate the mysterious dark energy that powers this phenomenon. The CFHT is being used to map the same area of the sky over and over again, looking for the tell-tale blobs of light that mark the spots of a distant, dying suns. The more of these we see, the better we can nail down the physical characteristics of the cosmic expansion, and of the dark energy about which we know so little.

Of course, astronomers will squeeze a lot of science from this and other images… but it’s also OK to simply scan and pan through them at home, too, marveling that the Universe is so deep and so deeply beautiful.

For more deep and gorgeous images like this, see Hubble Digs Deep to See Baby Galaxies, The Milky Way Bulges with Cannibalized Corpses, Hubble Pokes at a Galactic Bulge, or just search in the Pretty Pictures category of this blog.

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (56)

  1. Charles
  2. Dr. Bob

    Its easy to spot the stars. The point sources have diffraction spikes (stars) and the extended objects don’t (galaxies…and planets/moons, but none of those here).

  3. So, did they find any supernovae in this image?

  4. Hey. This is supposed to be the “Bad Astronomy” blog. Where’s all the “bad” stuff? If you keep posting all these “good” and “cool” things, I’m going to have to unsubscribe!

    Oh. Just in case… :-)

  5. The scale and scope revealed in these photos boggles. In a good way.

    We are one amazing universe.

  6. Ashley Moore

    So, is there an area in the sky, 5 times the size of the Moon, that has only 17 (by my count) stars?

  7. MetaEd

    I can feel the impact of this image in my stomach. This goes beyond beautiful into the profound.

    Please, Uncle Phil, tell us a story from the image. What’s this thing? http://metaed.com/philwhatsthis

  8. Mark

    If only early civilizations had seen this photo and understood its implications, the bible would likely not have been written as the fairy tale that it is.

  9. Quiet Desperation

    Test test 2 3… am, I getting through again?

    This is supposed to be the “Bad Astronomy” blog.

    Actually, was there ever a District 9 post?

  10. Firemancarl

    Wow, just simply wow!

  11. TDL

    Sigh… if only, as a skeptic, I could have a sense of wonder about this. 😉

  12. Parkylondon

    Absolutely sublime. I have a question about the term “degree”. I would have thought it referred to a linear distance rather than an area. Assuming it is, as it appears, an /area/ of sky does that mean there are 360×360 degrees in the night sky?

    Furthermore, if this is the case, does it also mean we can see 360 x 360 x 500,000 galaxies in the night sky? 64,800,000,000 is an amazing number!

  13. Alex Conley

    There are tens of thousands of stars (in our galaxy) in this image. The above poster is incorrect — only the very brightest stars show visible diffraction spikes, and these fields were chosen to have as few bright stars in them as possible.

    This is 1 of 4 similar fields from the CFHT deep survey, and about 100 supernovae were found in each field. But you don’t find them by looking at an image like this, instead you subtract old images from new images and look for things that change, and the subtracted images are a lot more boring to look at.

    And a square degree is a patch of sky one linear degree on a side. But there are only about 41,000 in the sky, since the sky is spherical, not square: http://en.wikipedia.org/wiki/Square_degree

  14. Lena

    Hey Mark (#8 post),
    The bible doesn’t refute anything about stars or the size of the universe. It admits there are stars (heavens). It’s mankind’s job/privilege to explore and discover all of these wonderful creations.

  15. PaleGreenPantsWithNobodyInsideThem

    I only count 100,000 galaxies in that picture.

  16. So “only” 20 billion galaxies would be visible to CFHT if it was outside the Milky Way and could get a proper look at things.

    I can live with that! :)

  17. MetaEd at number 7:

    My guess is that your “whatsthis” is two colliding galaxies, like the Antenna Galaxies (wikipedia link on my name) but the streamers of stars are invisible at this range.

  18. Gary Ansorge

    Pfui! A measly half million galaxies? I want a globular synthesis with about a billion galaxies showing. Now THAT would be,,,cool???.

    Great pic.

    GAry 7

  19. Oooh, I really like that big diffraction spikes shaped galaxy towards the bottom.

  20. Codswallop

    Beautiful pic, as usual. But let me ask you: What DO a half million galaxies look like?. “Bad Astronomy” doesn’t excuse bad grammar.

  21. MrCuriosity

    I hypothesized at the age of 16 that given enough time of exposure, an image would be solid white from the number of galaxies in the image.

  22. That’s amazing. Its incredible the technology that is being invented in this day in age. I’m glad I live in a time when I can view the universe like no other throughout history.

  23. Brian MtHood Man

    Postulation, is dark energy the balance of real energy. As in weather a high pressure gravitates to low pressure areas, could it be so simple! Or like in politics, disorder is the easy path! I am just an inquisitive soul, questioning the Universe!

  24. MrCuriosity – The longer you stare at the sky, the more galaxies you see, true, but you also resolve the galaxies you do see much better. Galaxies are spaced far enough apart on the sky that that would never happen.

    Some guy named Olber once said something similar – that the night sky should be infinitely bright because anywhere you look, if you go back far enough, there’s a galaxy. The solution, as seems obvious to us moderns, is that the Universe actually isn’t infinitely old, so there’s a limit to how far we can see. But this was a real puzzler back in the day 😉

  25. Joe

    Looks like a bunch of copypasta in that picture.

  26. Mark Brown

    Wait until Google plots all this and we can fly around in it.

  27. Bill

    Parkylondon, 360×360 would cover the full sky twice. Think of the globe. It is 360 degrees around the equator, and 90 degrees no the north pole, and 90 degrees to the south pole. If you start travelling North for more than 90 degrees, you loop back around south. You’ll also notice that the shape of a 1 degree box changes as you move north. Near the equator it looks like a square, and near the North pole it looks like a donut slice… Without know the longitude and latitude range this covers, it would be impossible to accurately determine what fraction of the total sky this picture covers.

  28. Timkatt

    I think you guys crashed the site

  29. Yojimbo

    Site appears to be down for the count. Either it doesn’t open or I get a big featureless black rectangle. (No, the monitor IS on, thank you :) )

  30. Rob

    I guess the reason its in Bad Astronomy is a legal one – just in case anyone whips his little brother into actually counting them, and coming up short 23,976 galaxies…

  31. Torbjörn Larsson, OM

    Postulation, is dark energy the balance of real energy.

    Well, dark energy is as real as other energy, that is why we can observe its effects. 😀

    But yes, it likely is the balance of the rest of the energy, as it seems the universe have zero energy.

    Though that is then a mere boundary condition of the problem. This, and observations of the rather different “rest of the energy”, doesn’t tell us what it is any more than knowing that there is a sea and tasting fresh water tells us how sea water taste.

  32. Will

    Our Universe rules! Woo-hoo!!!

  33. Messier TidyUpper

    Awesome. I love it. 😀

    Deep Fields seem to be all the rage at the moment – & why not!? 😉

    Had an article in the paper yesterday showing the HST image the BA blogged about t’other day –


    It now graces my pinboard. 😉

    BTW. Three quick questions if I may ask, please :

    1. Are we getting spectra on the galaxies here too or just the image?

    2. Is this a “true” colour / visible light image ie. what you’d see with the unaided eye in the right position (& time!) or not?


    3. Are the galaxies in this piccy identified as to their Hubble / galaxy classes – eg. quasars, AGN’s, spirals, barred spirals, ellipticals etc .. & are the galaxies here to be included in the “Galaxy Zoo” public computer astronomy outreach program thingy?

  34. Brian Too

    Do we have any kind of guesstimate on how many galaxies there are in the universe? I thought I heard that there were about 250 million or so. Don’t these deep field images keep adding to the total at a very considerable rate?

  35. Don

    Come on, “Discover,” ain’t you got no grammar? It’s “What DO half a million galaxies look like?”

  36. Blind Squirrel

    Around what are diffraction spikes diffracting?


  37. chonnes

    I view this image and try to comprehend the relationship between the size and dynamics of the observable universe relative to the size and influence of Earth. Just thinking about those two extremes makes it incredibly difficult to believe that a “creator” of some sort not only created all of this but is also actively concerned with my personal religious beliefs and sexual orientation. I’m not a creationist and the more I learn about cosmology and other sciences, the more committed I am to my own beliefs.

    On a side not: Is this site mirrored on the “Bad Grammar” blog too? It should be because it “do” not use the correct verb for 3rd person, present tense.

  38. BicycleRepairMan

    Do we have any kind of guesstimate on how many galaxies there are in the universe? I thought I heard that there were about 250 million or so. Don’t these deep field images keep adding to the total at a very considerable rate?

    Ramp it up, there is atleast 100 BILLION galaxies. On a related note, I read somewhere about how many galaxies there was behind a coin held on arms length (or something to that effect), and I THINK it might have been by the BA himself,but I cant remember the number, can anyone help me out?

  39. So “only” 20 billion galaxies would be visible to CFHT if it was outside the Milky Way and could get a proper look at things..

  40. @Mark,

    Have you ever read Isaac Asimov’s short story “How It Happened”? (If not, read it here: http://www.sumware.com/creation.html ) I like to think that that’s close to what happened. If the Bible (well, Torah to me) covered the actual events of creation (i.e. Big Bang and everything leading up to man’s existence), it would be so long that no one would have been able to read it. Certainly not anyone living a few thousand years ago and not even today. (Could you read a book that was over a billion pages long?) So the Torah/Bible touches upon it briefly in more of a metaphor format (like it does for many of the stories) . Unfortunately, some folks seem to be metaphor-challenged and read it as the literal truth.

  41. @BicycleRepairMan,

    100 Billion galaxies? That’s an amazingly huge number. With the number of stars and planets in those galaxies, I’d say life existing on another planet has got to be a statistical certainty. Of course, whether we can detect it (and communicate with it if it is intelligent) is another story.

  42. Dave Cortesi

    And what is this? It’s at the top, a couple of clicks from the left edge — and looks to me very much like a gravitational lens.



  44. Blind Squirrel


    And remember, your god who created these hundreds of billions of galaxies is very concerned about what you do with your genitalia.


  45. Zoomed in to try to find my grandmother.

  46. I hypothesized at the age of 16 that given enough time of exposure, an image would be solid white from the number of galaxies in the image.

    The fact that it doesn’t is one of the first arguments for the Universe being limited in extent. In these pictures, the blank spaces are places that are basically older than galaxies.

  47. zpmorgan

    Whenever the entire sky is captured, it will only be the 1st frame :)

    And out of curiosity, how far can Hubble zoom in on this?

  48. zpmorgan


    Here’s a funny looking one. It’s barred and symmetrical, but its arms wrap back around to form a figure 8.

  49. Alan Luvin

    Thank you to the scientists who made this ‘snapshot’ possible.
    Thank you to God who made this all possible.

  50. Alan Luvin

    Summer night away from the lights of the city in a field on your back staring up at the sky.

  51. DJGriz

    Thankfully God was equally concerned with sacrificing goats and coveting neighbour’s wives while he created 200 billion galaxies. I mean, where would we mammals be in God’s eyes if we didn’t repeatedly resonate air from our larynges in his honour! That’s the first thing I’d be insisting on after creating the hundreds of billions of stars we see in every direction. He must be right peeved with the amphibians who hardly lift a glass in his name these days! tut tut….


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