Stunning portrait of galactic triplets

By Phil Plait | July 27, 2011 6:00 am

Located a mind-numbing 350 quintillion kilometers away — 35 million light years, a mere stone’s throw on a cosmic scale — the Leo Triplet is a set of three interacting spiral galaxies, each much like our own Milky Way. It’s unusual for a professional observatory to get all three in the same image, but the 2.6 meter VLT Survey Telescope (VST) has a 268 megapixel camera, making it a snap to take a family portrait:

[Click to massively galactinate.]

How flipping awesome is that? This is one of those times I wish I could inlay a picture wider than 610 pixels; you really want to grab the hi-res version.

This incredible picture is a combination of green, red, and near-infrared filtered images (displayed a bit confusingly as magenta, green, and red respectively in the image above). The three galaxies are all spirals at varying degrees of tilt: M 66 at the lower right is the most open, NGC 3628 is almost exactly edge-on, and M 65 at the upper right is intermediate. Look at how prominent the central dust lane is in NGC 3628!

I’ve seen M 65 and 66 with my own telescope back when I was in high school, and I spent a lot of hours at the end of my driveway poking around the sky. They’re pretty bright, but oddly I don’t remember seeing NGC 3628. I wonder what I would have made of it? Now, with a couple of decades experience under my belt, I can see that the three galaxies are interacting: NGC 3628 has an inflated, puffy disk, and the you can see that wide-flung arm of M66. Those are clear signs the gravity of each of these galaxies is affecting the others.

Hubble snapped an amazing close-up shot of M66 last year, but there is something majestic and lovely about this wider, deeper picture. It really puts the galaxies in context, and astronomers can use that to see precisely how the galaxies are interacting. As usual, the marriage of science and beauty is clear and gorgeous when staged upon the sky.

Image credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute

Related posts:

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In galactic collisions, might makes right

CATEGORIZED UNDER: Astronomy, Pretty pictures
MORE ABOUT: Leo Triplet, M65, M66, NGC 3628, VST

Comments (35)

Links to this Post

  1. “BadAstronomy” a must read « Clark Planetarium | August 10, 2011
  1. Mark Nylund

    How close are they to each other and how would the others appear in the night (or day?) sky if one was living in one of them?

  2. Bert

    Am I the only one that looked at this and saw an intergalactic game of Breakout?

  3. marc

    click to massively throwupinate

    you ‘click to…’ stuff is really getting old.

  4. bobvilla

    What’s that red line of dots with a purple-ish halo to the right of NGC 3628?

  5. Messier Tidy Upper

    Hubble snapped an amazing close-up shot of M66 last year, but there is something majestic and lovely about this wider, deeper picture.

    It sure did – that photo of M66 is still up there as about my all-time favourite galaxy image. :-)

    This latest one is marvellously superluminous too! :-)

    How flipping awesome is that?

    Since you’ve asked : Very! ūüėČ

  6. @ marc:

    If thine eyes offend thee, pluckinate them out.

  7. Dust of the stars

    I like the “___inate” tags Phil, keep it up. It reflects your innate sense of wonder, which is a good thing. Marc can click to departinate if he finds it so tedious.

  8. Another hint that the galaxies are interacting is the Tidal Tail that NGC3628 exhibits. (Link to APOD)

  9. Dave Jerrard


    I also counted at least 7 trails in that image, most likely caused by Earth-orbiting satellites, and possibly one asteroid. The satellites appear as short lines, one half being red and the other half in magenta, caused by swapping filters.

    The possible asteroid is near the bottom, about 1/3 of the way from the left edge, and appears as two different colored dots right next to one another. This could be another satellite that didn’t move much, or something bigger & further away.

    Since only two colors show up in these streaks, I’m guessing the green filter was used at a different time, or satellites just don’t show up much in a red filter.

    He Who Has Caught Enough Satellites In His Own Photographs.

  10. Messier Tidy Upper

    @ ^ Dave Jerrard : Well spotted. Nice observation there – thanks. :-)

    @1. Mark Nylund :

    How close are they to each other and how would the others appear in the night (or day?) sky if one was living in one of them?

    Apparently, according to wikipedia :

    these three galaxies *are* all related & all located at about 35 million light years away.

    For comparison, the Magellanic Clouds :

    are 160,000 (LMC) and 200,000 (SMC) light-years away from us and those are much smaller than M66 and M65 :

    Plus they may have interacted with each other relatively recently (800 million years before now) – and still be doing so today or in the future.

    So I can’t really answer the question except to say that my guess on how they’d appear from each other is :

    S-p-e-c-t-a-c-u-l-a-r! 8)

    @7. Dust of the stars : Agreed and seconded by me. :-)

  11. Fred

    I can see a few other galaxies further away in the depth as well. But what are all those stars you can see sprinkled around the picture? Are they all stars of the milky way?

  12. Messier Tidy Upper

    Meanwhile in other news for those curious here :

    the landing site has been selected for the biggest and hopefully best Mars exploration rover yet -the Curiousity formerly the Mars Science Laboratory.

    A crater that’s (probably not) named for a West Indian cricketer. :-)

    See also via their home page here :

    Whilst this link :

    takes you to the Dawn mission’s

    dawning findings as it continues orbiting and imaging Vesta the brightest asteroid.

    Hope these are interesting / useful /enjoyable for folks. :-)

  13. Wayne on the Plains

    @ marc,

    If every image still entreated us to “embiggen”, you might have a point that the joke was getting stale. Making each one unique and fitting to the subject keeps the joke fresh for most of us, and gives Phil a chance to be clever and playful, which is a main reason many of us enjoy his writing so much.

  14. Marc, I agree with Wayne. Phil’s “click to …” texts are always perfectly cromulent.

  15. Regner Trampedach

    Dave @ 9: There are many red+magenta trails and there are also many lonely green trails, so your first guess is correct – the green pictures were exposed at a different time, while swapping the green and IR filters (red and magenta colored) took only a fraction of the exposure time.
    bobvilla @ 4: I think you are talking about the set of dots due right of a little below the center of NGC 3628 and about one third from the left edge (straight above Dave @ 9’s slow moving object). The sequence is .. .. in both the green and the IR filter. I am thinking it is caused by a fast spinning satelitte that is rather dark, but with highly reflective and asymmetric solar panels. The unequal spacing and the high contrast are puzzling, but could be explained by that scenario…?…
    Cheers, Regner

  16. jennyxyzzy

    There’s actually a few of them – for example, if you look just to the left of M66, you’ll see another. They all seem to have the left end being in magenta, and the right end in red, but the slope of the line can be different (there is one that slopes at nearly 45 degrees that I bumped into)

    My first guess was dodgy pixels in the CCD, but that doesn’t explain why you would get lines of dodgy pixels. So that leads me to the conclusion that they are actually moving objects. The fact that they change colour would be due to the applied filter changing with time. I can only assume that the red filter (displayed as green in the image) was taken at a much different time, but the (displayed) magenta and red filtered images were taken one after the other, tracking the objects as they moved in the sky. So – satellites or airplanes would be my guess.

  17. jennyxyzzy

    ha! damn you Regner! ūüėÄ

  18. WJM

    Whoever is forcing Marc to read Phil’s stuff, could you cut it out?

  19. aquanerd

    @ Mark Nylund

    M65 and M66 are roughly only 160,000 light years from each other… while NC3628 is about 300,000 light years from the two. So pretty darn close!!

  20. Michael Swanson

    Makes me wish I had a 10′ wide monitor.

  21. RwFlynn

    I just had a thought. Since galactic interaction often leads to deformed and altered shapes, that leads me to guess that our Milky Way isn’t so circular as it’s always imagined in pop-culture. Actually, now that I think about it some more, I’d be rather surprised if that is indeed the case. Is it even symmetrical?

  22. Jeff

    All three of these are easy to see through a 25cm or larger telescope under dark skies. I’ve seen them many times. Also amateurs have taken images that rival the ‘normal’ size image seen here. And even larger. Though of course none rival (yet) the full resolution of the actually camera used! :)

    The area of Leo, Virgo, URSA Major, Leo Minor, and Canes Venatici are littered with galaxy duets, triplets, etc…

    Also of interest is all the smaller galaxies in the image. Images like this when converted to gray scale, inverted, and stretched make wonderful finder charts for trying to track down some of those faint fuzzies visually using 40cm or larger telescopes from a dark site. Fun stuff…

    C U under the stars…

  23. Regner Trampedach

    Mark @ 1: Well, Multiplying the apparent size (8.709 minutes of arc) of M65 by the distance ratio (35 Mly / 160 kly) one gets a width of almost 32 degrees across the sky! – Three times larger than the LMC! (the moon is 0.5 degrees). The surface brightness (per area in the sky) stays constant with distance, while the total brightness decrease with 1/distance^2. The total brightness will probably be more than 9 times larger than for the LMC, as I think the central surface brightness of M65 is larger than for the LMC.
    In short – it would be absolutely awesome! (as pointed out before :-)
    jennyxyzzy @ 17: Sorry :-/
    Cheers, Regner

  24. Douglas Troy

    Oh look, NGC 3628 is spilling his stars all over the place. :)

  25. This is a really, really cool picture! What makes me freak out even more is when you start looking at all the little spots in the background, and realize that almost all of them are galaxies as well… My brain rejoices in being in the presence of scales that it cannot comprehend: how weird!

  26. Chip

    Perspective can be tricky when we’re applying the tiny human scale to such staggering distances but if we were on an Earth-like planet in the outer spiral arm of any of those three galaxies, would we be able to see the others – out in the country – naked eye, as we do with Andromeda? Or would they be too far away. Just curious.

  27. Quagmire

    That trio was one of my favorite telescopic targets about thirty years ago, before suburban sprawl came my way and light pollution extinguished all the galaxies. The edge-on galaxies like NGC 3628 are particularly striking as seen through the telescope, and 3628 is one of the better ones. As I recall there is another bright galaxy – NGC 3593? – a short distance away from this group.

  28. Clint

    Totally agree Michel @25. These photos always stagger the mind and I like to revel in such staggering.
    “The universe is a pretty big place.” ‚ÄĒ Carl Sagan (Contact) is the understatement of…. forever.

  29. Regner Trampedach

    Chip @ 26: Could we see them? Absolutely – see my post at #23.
    Cheers, Regner

  30. Jon Hanford

    Regner #15
    jennyxyzzy #16
    Dave #9
    bobvilla #4

    Remember, Leo is a zodiacal constellation. Those trails are asteroids! From the ESO Press Release:

    “Very much closer to home, this image also contains the tracks of several asteroids within the Solar System that have moved across the images during the exposures. These show up as short coloured lines [4] and at least ten can be seen in this picture. As Leo is a zodiacal constellation, lying in the plane of the Solar System, the number of asteroids is particularly high.”

    The exposure showing green trails was taken on a different night than the exposures with the red-magenta trails which were taken sequentially on the same night. I’ve been looking at a larger(260Mb) image downloaded from ESO and so far I’ve found 17 (some are really tiny, so look close). Happy Hunting! :)

  31. I love pictures like this – cause when you go all super high res like that you can see also these other tiny little galaxies that look like stars in most other pictures, until you realize – holy crap, that’s actually a galaxy ūüėÄ

    My favorite galaxy is the one right near NGC 3628 – look for that super bright star to the center-right of it, and on the upper right hand corner is a nifty spiraly galaxy.

  32. Regner Trampedach

    Jon Hanford @ 30: Thanks for reading the actual press release for us. As to the asteroids – I kinda suspected as much, since the trails and the gaps between the two colors were pretty short, and judging from the depth of the exposure and the time it normally takes to change filters, they would have to be rather slow moving objects. Thanks for confirming that one.
    Cheers, Regner

  33. Joseph Lowrey

    first visit to this forum; there are haters everywhere, aren’t there?

    anyway, that’s a remarkable image unlike any i’ve seen before, and i’ve already set it as my desktop background

  34. I was looking to see if that little smudge just to the right of NGC 3628 was a dwarf galaxy getting eaten or just a gravitationally thrown chunk and found that there are a lot of images of that galaxy with a gigantic tail. The thing is the tail is pointed in the same direction as the spin of the galaxy and not in any way toward the other two galaxies so I’m wondering how gravity managed to pull that off that far. I’m also wondering why the tail didn’t show up in this photo even a little. Good stuff though even though I’m late to the party.


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