In the dark abyss, a slightly warped mirror on the Milky Way

By Phil Plait | February 3, 2012 7:00 am

There is just something wonderful when Hubble points to nearby spiral galaxies. Sprawling and detailed, we get both great resolution on smaller features as well as a jaw-dropping overview of a grand spiral… like, say, NGC 1073:

Yeah, I know. [Click to galactinate -- I had to shrink it to fit here, and it lost a lot of the coolness when I did -- or grab the 3900 x 3000 pixel version.]

NGC 1073 is a decent-sized spiral galaxy about 60 million light years away. It’s actually part of a small, tight group of galaxies many of which are far more famous (like NGC 1068). But 1073 is important because of a simple property: it looks like us.

While it’s not a perfect match, NGC 1073 does bear an interesting resemblance to our Milky Way galaxy (UGC 12158 looks more like our galaxy, but is far bigger, for example). Both have large, rectangular bars going across their centers. Bars are a bit odd, since you’d expect the arms just to wind all the way down to the center. But the gravity of a galaxy isn’t like the gravity of a solar system, with a big heavy star sitting in the center. Galaxies have their mass spread out over a long distance, so what gas and dust clouds and stars feel in the way of gravity is different, and bars are a natural outcome of that. However, they’re still not perfectly understood. Bars may form when galaxies collide, and they might be an indication of a galaxy reaching middle age. Perhaps there are other factors as well.

Studying galaxies like NGC 1073 will help us understand how bars form, and why we have one too. Remember, we’re stuck inside our galaxy and can’t see it from the outside (that picture above is an illustration based on detailed observations). It really helps our understanding of the Milky Way to observe galaxies like ours.

An important thing too is that the two galaxies are different in some ways: NGC 1073 has more open arms, for example, compared to our more tightly wound arms. Those differences are telling us something as well. What is it that makes one galaxy hold its arms closer in, and another to fling them out? Why does this galaxy have two arms, and that one three? If you can look at two galaxies that are alike except in one way, it’s easier to isolate the cause. So studying NGC 1073 is a great way to study ourselves.

It always makes me think of Nietzsche, who wrote on the nature of man, "And when you gaze long into an abyss, the abyss also gazes into you."

But on the nature of the Universe, it changes: "And when you gaze long into an abyss, your gaze falls back on yourself."


Related posts:

- The Milky Way’s (almost) identical twin
- Barred for life
- Unwind with some spirals
- Setting the bar
- Sculpting a barred galaxy

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (31)

Links to this Post

  1. Friday Links | February 25, 2012
  1. that picture above is an illustration based on detailed observations

    I don’t know how many times I’ve had to explain to people that any picture of the Milky Way that shows the entire galaxy is not an actual picture… I guess people just can’t intrinsically understand the vast distances involved in astronomy. YahooAnswers! is a particularly entertaining/depressing place to go if you want to see people totally failing to grasp the scale of the universe.

  2. ctj

    is there any good theory as to how bars are formed or persist? i’ve seen models of spirals as a phenomenon of bunching orbits, but i don’t think any depictions of them show bars.

    wikipedia says something about orbital resonances, but leaves it at that with nothing further. my 1987 fundamental astronomy (karttunen et al) merely mentions that the mechanism is unknown.

    if bars are transitory, shouldn’t we see clear examples of bars emerging and disappearing?

  3. Jess Tauber

    Galaxies with bars in the center have happier citizens than those whose people have to drink at home alone. At the same time, though, sometimes cliquishness can diminish the friendly atmosphere. Those with more open arms will likely be more popular with the tourists.

    The Most Interesting Man in the Universe
    (Stay Thirsty My Friends- Drink Gloog).

  4. Thanks for your redundant rephrasing of Nietzsche,
    When after all that is exactly what he meant.
    When we gaze into the abyss we eventually gaze at ourselves,
    Which is the purpose of astronomy.
    For more on the philosophical and religious nature of astronomy
    Check out Roger S. Jones, Physics as Metaphor.

  5. Mejilan

    I always wondered just how we knew so much about the shape of our own Milky Way. I mean, we’ve got a VERY skewed perspective of it compared to just about any other galaxy we’re currently capable of directly observing in some fashion or another. Still, looking at NGC 1073… Damn but she’s beautiful, ain’t she? :)

  6. Ross Cunniff

    Two bars go into a galaxy…

  7. Other Paul

    What I wants to know is this. Does the Milky Way have a proper name? The aforementioned seems more descriptive than nominative, and harks back to a time when we didn’t know any better. I’m assuming it’s not NGC 0.

    Oh, and, @Ross – hah!

  8. Tensor

    What I found interesting wasn’t so much NGC 1073 (although it is gorgeous) but the three tiny, red and I’m assuming distant galaxies in the upper left hand corner of the picture.

  9. alfaniner

    Looks like a classic freeze-frame from the old Lost in Space cliffhanger.
    7-6-5-4-3-2-1

  10. Lorena

    hehe I thought about posting that picture of NGC 1073 on my facebook with a big title PHOTO OF THE MILKY WAY!!!!!!! ….. and see who falls for it…. but I dont think anyone on my facebook would care even if it was real photo of it :O :O

  11. The sun and you and me and all the stars that we can see
    Are moving at a million miles a day
    In an outer spiral arm, at 40,000 miles an hour
    Of the galaxy we call the Milky Way…

  12. Other Paul

    So remember, when you’re feeling very small and insecure,
    How amazingly unlikely is your birth,
    And pray that there’s intelligent life somewhere up in space,
    ‘Cause there’s bugger all down here on Earth.

  13. SkyGazer

    When I look up and see the Milky Way, that glorious big band of stars, is that the bar of our galaxy?

  14. @ SkyGazer (#14) nope. It’s just the closer arms that you are really seeing. The central bar is blocked by all the intervening gas and dust. Although maybe some objects from that area are visibile from here (I honestly don’t know), most of what you are seeing is just stuff in a relatively small circle around the “Sun” point in the graphic Phil put up for us.

  15. Pete Jackson

    @Larian LeQuella: You can see a small portion of the nuclear bulge of our Galaxy, just outside the disk of galactic dust, below the direction to the galactic center in the constellation Sagittarius. It’s called Baade’s Window, named after the famout astronomer Walter Baade who used the Palomar 200-inch telescope to study the stars in the nuclear bulge. It’s easy to see Baade’s Window when looking at deep photographs of our Milky Way using a fish-eye lens.

  16. SkyGazer
  17. Dragonchild

    @3. Jess Tauber
    “Galaxies with bars in the center have happier citizens”

    So say the drunks. To the rest of us it’s like any other, a gigantic black hole which sucks up everything around it and there is no escape. Joy? Hope? They’re ground up and then lost forever. What happens in the black hole, stays in that black hole. Even if you’re “lucky” and avoid getting sucked in, you just keep going ’round and round until you burn out.

  18. amphiox

    What I wants to know is this. Does the Milky Way have a proper name? The aforementioned seems more descriptive than nominative, and harks back to a time when we didn’t know any better. I’m assuming it’s not NGC 0.

    This reminds me of a question I’ve always had:

    If we were to name the earth according to the conventions used to name exoplanet, would it be Sola (for that matter, would the Sun be Sol?), as the first planet around the star to be discovered, Solc, as the third planet counting from in to out, or Solf, as the sixth planet to be confirmed by science to be a planet?

  19. Messier Tidy Upper

    Marvellous image, stunningly beautiful galaxy, love this shot! :-D

    Oh & I don’t mind at all that its not a Monday either. ;-)

    *****

    @20. amphiox :

    Well, “Sol” isn’t really an exoplanet star’s name – it’d usually be a catalogue designation with an acronym abbreiv. (say Kepler Object of Interest) followed with a series of numerals eg. KOI – OOOOOyegods its too bright to view! ;-)

    Exoplanets are labelled in terms of their discovery but I’m not exactly sure when our Earth was discovered to be a planet as such versus the realisation that the “wandering stars” were worlds as well. Galileo maybe? We kinda found the existence of planets being like Earth rather than the existence of Earth as a planet if that makes sense? If planets are found simultaneous then they get lettered in sequence out from the star – I think. So I suppose we’d call Earth KOI-0 (zero) c or maybe Kepler Zero f assuming we count the earlier classical planets (Mercury, Venus, Mars, Jupiter, Saturn) as being discovered first.

  20. Messier Tidy Upper

    Again @20.20. amphiox :

    So I suppose we’d call Earth KOI-0 (zero) c or maybe Kepler Zero g assuming we count the earlier classical planets (Mercury, Venus, Mars, Jupiter, Saturn) as being discovered first.

    Correction – Earth would be Kepler Zero g – because i dn’t know my a., c’s well enough – d’oh! ;-)

    Kepler exoplanets listing~wise I think we’d have our solar system “named” (if you can call it that) as follows :

    Sun – KOI – 0

    Mercury – Kepler Zero b
    Venus – Kepler Zero c
    Mars – K0 d
    Jupiter – Ko e
    Saturn – K0 f

    The first “planetes” (not a typo) known originally as wandering stars.

    Earth – K0 g

    Once we knew we were one of them! Then we went on to find :

    Ceres – Ko h
    Pallas – Ko i
    Vesta – Ko j

    Plus Juno but it and the other asteroids are insufficently round to qualify for planetary status – as may be Pallas and Vesta too.

    Ouranos – K0 k
    Neptune- k0 l
    Pluto – K0 m
    Haumea – K0 n
    Sedna – K0 p
    Makemake – Ko q
    Eris – Ko r

    and so on.

    Quite what they’re going to do when the number of planets confirmed around a star exceeds 26 I don’t know! ;-)

  21. Ross Cunniff

    @22 Messier Tidy Upper – mostly agree, but Ouranos (Uranus) was discovered by Herschel in 1781, 20 years before 1 Ceres so it would be:

    Uranus – K0 h
    Ceres – K0 i
    Pallas K0 j
    Vesta Ko k

    and then i agree with your ordering.

  22. One thing I’ve always wondered about galactic structure (and was actually thinking too hard about just the other day) is how much the distances involved lead to weird relativistic effects with the interactions of gravity. Is it possible that the bars (and spiral arms in general) are basically a standing wave pattern set up by the time it takes for gravity to propagate?

  23. That’s a spectacular photo! Thanks for sharing… :)

  24. SkyGazer

    @Dragonchild
    ehm… to be fair.
    Black Holes don´t suck.
    google it

  25. Chris Winter

    Wow! NGC 1073 is one of your better galaxies. It’s not a downstream galaxy. It ain’t no flatland galaxy. (It’s not a Coor’s beer galaxy either.)

    The interesting thing about that image for me is that when I look at the central disk, it seems to be an edge-on photo of a smaller galaxy. Then I look at the spiral arms and my mind thinks there ought to be another galactic core hidden behind there somewhere. Just an illusion, obviously.

    BTW, Jess Tauber: I wrote the above before I saw your #3. Good one!

  26. Paul: What I wants to know is this. Does the Milky Way have a proper name? The aforementioned seems more descriptive than nominative, and harks back to a time when we didn’t know any better. I’m assuming it’s not NGC 0.

    I suggest NGC 127001.

  27. @Tensor : I agree, I came here to point out exactly the same idea. In full glory, they are island universes beyond the veil of NGC1073, and I want to know more. Like, why are they so red? They can’t be that far away, surely, that redshift is so visible to our puny eyes?

    @SkyGazer… It depends on how far away you are from the black hole.
    I’d have to say that a given black hole’s ‘suckiness’ is inversely proportional to the distance of the observer… but I could be wrong, methinks.

  28. Messier Tidy Upper

    @23. Ross Cunniff :

    @22 Messier Tidy Upper – mostly agree, but Ouranos (Uranus) was discovered by Herschel in 1781, 20 years before 1 Ceres .. and then i agree with your ordering.

    Good point – thanks for that. :-)

    I also missed K0 o too. Oops. Guess that’d have to be Orcus or Varuna or Ixion or another of the ice dwarfs.

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