Have You Ever Seen A Galaxy ?
    By Tommaso Dorigo | March 15th 2010 04:13 AM | 19 comments | Print | E-mail | Track Comments
    About Tommaso

    I am an experimental particle physicist working with the CMS experiment at CERN. In my spare time I play chess, abuse the piano, and aim my dobson...

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    Have you ever seen a galaxy ?

    I mean, not a picture of one. The real thing. A picture is a representation of reality, and as such it conveys to our senses only a pale suggestion of the stimulation that experiencing the real thing provides. In a world where images, still and in motion, have a dominant role in our lives, we tend to forget how different are some things when we experience them directly.

    Well, seeing a galaxy -getting their multi-million-year-old photons streaming directly through your pupils- is as different from seeing it pictured as tasting a glass of Amarone is different from watching the bottle. I chose a bottle of wine for the sentence above because I know that not everybody likes wine, and to fully enjoy a glass of Amarone requires some palatal skills. The same goes with the sky's wonders: everybody may like to peek through an eyepiece in a big telescope, but few will fully appreciate the sights, as I have learned through years of amateur astronomy, a bit too often let down by the less than enthusiastic reactions of relatives and friends.

    Last Saturday I imposed to myself a real tour de force in order to make it to a rendez-vous with other amateurs in a remote place in the Alps. Here is an executive summary of the day, just to give you the flavour of the importance I gave to the meeting:

    6AM: wake up at the CERN Foyer
    6.40: take a bus to Gare Cornavin in Geneva, jump into train
    15.30: arrive home, have a quick lunch with family, change clothing, put on warm ones, prepare bag for night out
    16.30: bring Filippo by car to a store in Marghera to buy his birthday present (he will turn 11 on the 19th)
    17.30: leave Filippo at P.le Roma, bolt away headed to Padola, a place in the mountains 100 miles away
    19.00: reach home in Padola, load telescope in trunk of car; leave to Auronzo, 10 miles away
    19.35: arrive at restaurant, meet other amateurs, dine
    20:40: leave to Val Visdende, 20 miles away, at the border with Austria
    21.20: arrive, unload, mount telescope, enjoy the views
    3AM: after six hours at -10 degrees centigrades, call it a night, unload, leave to Padola, sleep a few hours
    9.00: leave to Venice
    11.00: arrive in Venice.

    So you can see that it was not totally painless. Nevertheless, it was well worth it -at least given the importance I gave to the meeting with those photons.

    But now take their stand for a moment -let's look at things from a different perspective. Twenty four million years ago a stream of photons is emitted from the surface of a few billion stars in a galaxy far away. Those photons are already quite old: they were created thousands of years before in the core of those stars, and only then do they emerge and leave the stars in straight paths.

    The galaxy stars emit photons in all directions, but on any given second a few hundred thousand photons happen to travel in a direction so exactly aligned that the angular separation in their trajectories is a ridiculously small number: they have to converge to a target which has the angular size of three billionths of a billionth of a degree. And they run, and run, and run through empty space, for twenty-four million years. They left the emitting stars when there were still dinosaurs on our planet, but now, as they approach us, it is not a dinosaur who turns a telescope in exactly their direction and places his eye on the lens. The photons hit his retina, and the image of the galaxy is collected to be finally enjoyed.

    The picture above (credit: bellatrix observatory), which I picked among a set of many much more beautiful ones that may be found with a google search for "M101" -the pinwheel galaxy-, is remarkable because it very closely matches what I could see last Saturday through the eyepiece of my friend Mauro's 24-inch Dobsonian telescope.

    By looking at the image you should not fail to observe the intricacies of the spiral arms and their asymmetric, broken shape, the condensations within the arms, the central bulge, and a few dark bands. All of that was there, for me to enjoy.

    The night was moonless (by construction), and very dark even for the alpine site we had picked: it lent itself perfectly to a rich galaxy-observing session, so I observed some forty galaxies during the night. Forty streams of photons, emitted in concert from five hundred million years ago to a few million years ago in directions precisely determined, such that they would enter the tube of Mauro's telescope (see picture on the right) or my smaller 16-incher for a well-timed rendez-vous. And I am not even explaining that in some of the views I could count 11 different galaxies in the same field of view: 11 streams of photons converging into my retina. That is really something!

    If you consider treating yourself one day to a similar show, start planning now. The photons you are going to intercept have been working their way to your eye since a long time ago already.


    aahhh... Amarone! Sadly, no chance of some where I live now.
    And yes, it reminds me of our little 6-inch Newtonian at school - fantastic views of the Moon.
    Need a grown-up telescope for galaxies :-)
    Well, Amarone is expensive everywhere... I dare not ask how much a bottle costs in the US.

    To tell the truth, we had a 8" scope (a Celestron CPC) there too, and the galaxies did show up there pretty neatly too. The single most important ingredient is a dark sky!

    I think it is important for people to view directly, a spiral galaxy...
    It is one thing to view a picture, that can be faked, and explain to someone that our home, is surrounded by galaxies.
     Yet another to have them look through the looking glass, and see it for themselves, and move something themselves in front of the objective lens, to know, they are indeed looking at the sky, nothing, is being faked.
     An example, with my son, I hooked up a solar panel to a radio (with no battery) then had him put his hand to shade the solar panel, the radio went silent. He did this then, over and over again, giggling.
     With a battery in it, explaining it is being charged by the solar panel, all they can do is understand the explanation. Without the battery, they can take part, of seeing it for themselves what the solar panel and sunlight are doing.
     Viewing other galaxies directly, through a telescope does this same thing, it gives them first hand proof, and if they alter the telescope, the resulting view is also altered.
     First hand, witnessing, we live in the universe, rather than just being told that.
    It provides a kind of magic of first hand experience, a magic that cant be found in any text book or photo, in my opinion.
     It replaces what has to be believed, with first hand experience, of the real universe we live in, that, kind of magic.
    Poor photons! You ended they journey!

    Unless... they prefer your telescope, and your iluminated post about them, than hitting the ground.

    Someday I will look directly at a galaxy myself tool.

    Great article.

    Thank you Marcelo. Please try and find a dark site and a telescope of good aperture.

    Meet Herschel (that's what I've named him) my 8" Dob and my favorite toy....
    And yes, I have seen many galaxies first hand, through this and many other telescopes. The first galaxy I saw was when I was taking classes at the Adler Planetarium and Astronomy Museum. It was M31 and it's two satellite dwarf ellipticals M32 and NGC 205 (M110). As part of our class, we would go to the observatory behind the Adler and look through the 20" Ritchey-Crétien Cassegrain on a computer driven fork equatorial mount. As we watched the image build on the display of the CCD, we, at the same time, viewed the galaxy directly through an eyepiece, and it was spectacular. I mean, just the thrill of seeing something, knowing what it is and how far away it is, is an experience that you simply can't put into words.

    Over the years I have looked through many telescopes of different apertures up to 25"--reflectors, refractors, catadioptric and seen a whole host of galaxies and other DSO. And even when they're only little fuzzies, just knowing what you're looking at is awe-inspiring.
    That's true Eric, and in fact, we spend most of our time on the hardest ones to see, the tiniest fuzzies. Lots of Arp objects typically. It's a thrill.

    Ahhh.....and for me, who just looks up at the sky without a telescope, the most impressive part of your blog post was.....

    "And they run, and run, and run through empty space, for twenty-four million years. They left the emitting stars when there were still dinosaurs on our planet, but now, as they approach us, it is not a dinosaur who turns a telescope in exactly their direction and places his eye on the lens. The photons hit his retina, and the image of the galaxy is collected to be finally enjoyed."

    How poetic! Perhaps when the telescopes are set up again one night in Ft. Tryon park in New York City, I'll venture on up there to take a peek, and think about not only stars and galaxies, but dinosaurs as well.

    Suzan please do that. Think at the journey those photons took. It is awesome.

    You can be sure I will!

    Very, very nice post Tommaso - I've got to dust off my telescope and do some observing of my own. With a 150 mm Maksutov I do need pretty dark skies to enjoy seeing the old photons of distant galaxies. As Suzan, I was also impressed by your "And they run, and run..." paragraph; sounds like you were channeling Carl Sagan there! However what impressed me the most was that you spent 6 hours in -10 deg. C, wow!!

    Ah Changcho, that is the bitter but necessary part - but I did not suffer too much, because there was always something to do, and going up and down the ladder to observe on the big 24" was enough to warm me up. I remember another time when the temperature was -17 degrees and I stood for four straight hours in the middle of nowhere, looking at the Quadrantid meteors (it was a January 4th). That once I thought I was going to die for the cold!

    Mark Changizi
    See a galaxy! I didn't see nary a star during my entire time in Los Angeles! (Typically 14 planes and two stars out. I live now in NY though, with a better view. Thanks for the piece.)
    Are the photons really a few thousand years old when emitted from the surface of the star? I always thought the photons where constantly absorbed and re-emitted by atoms in the star as they propagated to the outer surface.

    Actually, from the photons viewpoint, the journey from the star to your eye was instantaneous and the distance between your eye and the surface of the star is 0 due to relativistic effects. Hope your eye didn't get burned holding it so close to the star in the not so distant galaxy.

    Hi Dave,

    the photons get created in the core of stars, and it takes them a million years to get out.  Of course you may question their individuality, but the transport equations explain what is their typical diffusion.

    Er ... we just have to look up to see the Magellanic clouds ...

    True kea, but many have not even seen the milky way in their whole life!! Anyway looking at a distant blip in the sky through a big telescope, and discovering its morphology, is something else. Cheers! T.
    We need more encouragement to start appreciating the night sky. This article does just that. Great.
    I was lucky enough to observe several galaxies and other deep sky features and they really make you tick.

    Just one little thing if we are talking about a galaxy 24 million light years away. Dinosaurs died out about 65 mya so, they couldn't have lived on Earth 28 mya.

    Hi adjas,

    sure, 24 million years is too little time... I just picked one galaxy for an example, but of course you can observe ones that are twenty times farther with no problem.