Human Journey

How to “See” Beyond the Milky Way From Your Backyard

by Robert J. Vanderbei

April is galaxy month.

The arc of the Milky Way—our home galaxy—dominates the summer and winter nighttime skies. But in fall and spring, depending on the time of night, the Milky Way is usually seen making a ring around the horizon.

For example, at midnight on April 15 the Milky Way will be both setting in the west and rising in the east.  Hence in April the bulk of our galaxy is out of our field of view, and we get great views of objects that lie beyond the Milky Way—such as other galaxies.

Shown here is a picture of a patch of sky in the constellation Canes Venatici, the Hunting Dogs. The image contains several galaxies, the biggest of which is Messier 106. Click the pic to see the full-size version.

—Picture by Robert J. Vanderbei

M106 is a barred spiral galaxy about 26 million light-years away from us. Based on analyses of x-ray images, it is thought that M106 contains a supermassive black hole at its center into which material from the galaxy is steadily falling.

The second biggest galaxy in the picture, seen at the lower right, is called NGC 4217. It is a spiral galaxy, but from our vantage point, it appears edge-on.

These two galaxies are about the same distance from us and hence are neighbors of each other. If you look carefully, you will spot at least four or five additional smaller, fainter galaxies.

M106, NGC 4217, and perhaps some of the other galaxies in the picture belong to a gaggle of galaxies called the Canes II Group.

Unfortunately, light pollution has made it difficult for most observers to see galaxies through a telescope in their backyards, as most of us live either in cities or the suburbs. To see these objects visually through a telescope, you have to go to a place where the night skies are very dark.

But there is an alternative. If you are willing to settle for a photographic record as opposed to a direct visual observation, you can take a picture of many very faint objects even from light-polluted locations.

I took the picture shown here from my driveway in light-polluted New Jersey. I attached a CCD camera to my four-inch refractor and collected several two-minute exposures that I then stacked on my computer to make the final picture. The total exposure time was 196 minutes.

There is another pretty grouping of three galaxies visible in April called the Leo Trio, so named because they can be found in the constellation Leo.

(Get more on how to find Leo in the spring skies.)

The Leo grouping consists of M65, M66, and NGC 3628. These three galaxies are all about 35 million light-years from us and therefore—just as with the Canes II group—they are neighbors of each other.

This picture is a stack of 31 three-minute exposures. Again, click to see it larger.

—Picture by Robert J. Vanderbei

Note that anyone can stack astroimages using Photoshop: File -> Scripts -> Load Files Into Stack.

However, it’s not the easiest way to do it—in fact, I think it would be quite tedious to stack a large number of images without a customized script.

I use a program called MaxIm DL. It’s pricey but full featured.

There are a few other popular choices, such as CCDstack and ImagesPlus, and there are freeware programs such as DeepSkyStacker and Registax II (which is designed for imaging planets but can be used for deep-sky objects, too).

I haven’t used it myself, but for those who prefer freeware, I’ve heard only good things about DeepSkyStacker.

Robert Vanderbei

Robert J. Vanderbei is chair of the Operations Research and Financial Engineering department at Princeton University and co-author of the National Geographic book Sizing Up the Universe. Vanderbei has been an astrophotographer since 1999, and he regularly posts new images on his astro gallery website.

Robert J. Vanderbei is chair of the Operations Research and Financial Engineering department at Princeton University and co-author of the National Geographic book Sizing Up the Universe. Vanderbei has been an astrophotographer since 1999, and he regularly posts new images on his astro gallery website.
  • […] APRIL IS GALAXY MONTH!! Get your stars on, yo. – National Geographic […]

  • Fhamela Cuevas

    That was really facinating, or should I say intersting. Thank you for the facts

  • VIKRAM222


  • Scott Berns

    Very cool. I look forward to scanning the skies.

  • jorgi

    ah opo wi aku ra mudeng su

  • Jerry Kelley

    I’m curious what kind of Instrument was used as the Lens and What Focal Length was needed to produce this image. There’s not enough information presented. Astrophotography is NOT as easy as he makes it out to be, although it’s certainly easier now with Digital Cameras, than it was when we used Film

  • Robert Vanderbei

    Jerry: You’re right, I gave too little information. You can find a little bit more information on my M106 page…
    There’s also general information about my equipment on my main gallery page…

  • daihrat

    Que paisaje tan hermoso, saluds amigos!!!

  • Ali

    There’s only one word to describe this…

  • Oscar Sifuentes

    Thanks National Geographic I have searched them before using Sky & Telescope, Astronomy Magazine, and now I am following your instructions to locate these distance Galaxies! How Cool is that! The Star Hunter

  • rusman hadi


  • allen

    amazing its realy great to know more about our galaxy….

  • soufian abdeslam

    I like thes films and I love the Channel Nat Geo Abu Dhabi

  • soufian.abdeslam

    I like thes channal NAT GEO ABU Dhabi

  • michael sadowski

    Still some great dark-sky viewing in and around my home base of operations. No need to drive too far to find some excellent, lightly populated spots in the nearby foothills of the Santa Monica Mtns. and, to the north, the Santa Susana. My question is this: what is this “stacking” lengthy exposures technique to capture such fine images as Mr. Vanderbei’s? He says he “stacks” his exposures on Photoshop but what’s the basic concept at work here: I know nothing about astrophotography but might like to try my hand some day. “Stacking” suggests to my uneducated mind, sounds like a procedure that would darken the final images?



  • RENAUD Jean-François

    Il est vraiment intéressant de se questionner sur l’origine de ce monde infini que l’on habite. C’est bon de savoir que des hommes sont à l’œuvre pour tenter de comprendre. Les image fantastiques, que les chercheurs nous font découvrir sans cesse, nous pousse à la méditation. Sommes nous suffisamment équipés cérébralement pour comprendre.? On sait que notre univers, et donc nous-même, sommes constitué d’atomes. C’est atome sont éternellement recyclés. Aujourd’hui ici, demain ailleurs…Et notre conscience, de quoi est-elle constituée.?

  • jose capera

    cada vez la vida lactea se agranda porque nacen mas galaxias mas estrellas, algunas naceran fuerte otra debiles, todo esto que sucede es porque ese ente espiritual tiene vida que no se ve pero que esta ahi.

  • Misun Hong

    It;s so interesting and attractive enough to catch these galaxies. I enjoyed a lot while reading this article and seeing pictures. thanks

  • Bharti H Jadhav.


  • Kausor Khan


  • jinzky

    thats awesome!!!

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