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Hoag's Object Is a Galaxy Within a Galaxy Within a Galaxy (and Nobody Knows Why)

With a perfectly symmetrical ring circling a red sphere of stars, Hoag's object is one of the prettiest mysteries in the universe.
With a perfectly symmetrical ring circling a red sphere of stars, Hoag's object is one of the prettiest mysteries in the universe.
(Image: © NASA/ESA/Hubble)

Look closely at the serpent constellation slithering through the northern sky, and you might see a galaxy within a galaxy within a galaxy.

This cosmic turducken is known as Hoag's object, and it has befuddled stargazers since astronomer Arthur Hoag discovered it in 1950. 

The object in question is a rare, ring-shaped galaxy measuring some 100,000 light-years across (slightly larger than the Milky Way) and located 600 million light-years from Earth. In a recent image of the oddball object taken by the Hubble Space Telescope and processed by geophysicist Benoit Blanco, a bright ring of billions of blue stars forms a perfect circle around a much smaller and denser sphere of reddish stars. In the dark gap between the two stellar circles, another ring galaxy — much, much farther away from us — peeks out to say hello.

Related: The 15 Weirdest Galaxies in Our Universe

What's going on here, and what tore Hoag's object in two? Astronomers still aren't sure; ring galaxies account for less than 0.1% of all known galaxies, and so they aren't the easiest objects to study. Hoag himself suggested that the galaxy's peculiar ring formation was merely an optical illusion caused by gravitational lensing (an effect that occurs when extremely high-mass objects bend and magnify light). Later studies with better telescopes disproved this idea.

Another popular hypothesis suggests that Hoag's object was once a more common, disk-shaped galaxy but an ancient collision with a neighboring galaxy ripped a hole through the disk's belly and permanently warped its gravitational pull. If such a collision occurred in the last 3 billion years, then astronomers looking through radio telescopes should have been able to see some of the fallout from the accident. No such evidence has been found. 

If there was a cosmic crash at the core of Hoag's object, it must have happened so long ago that all the evidence has been swept away. With only a handful of other known ring galaxies available to study (none of which shows the perfectly symmetrical characteristics found in this one), Hoag's object remains a mystery wrapped in a riddle inside an enigma — you know, like a turducken. 

Originally published on Live Science.

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  • d3bug
    It's Marbles... all the way down.
    Reply
  • mintaslanxor
    You lost your marbles? Sad!
    Reply
  • Ron
    Maybe it’s the other side if a Black Hole
    Reply
  • fyrefly
    What figures are being used for the statement that Hoag's is "slightly larger than the Milky Way"? I've previously seen our galaxy's diameter given as 150,000+ light-years.
    Reply
  • Joe Weil
    Fyrefly- 105,700 lightyears.

    Why people post misinformation when the correct information is right at your fingertips is beyond me. It explains our undisciplined society in a microcosm.
    Reply
  • fyrefly
    Joe Weil said:
    Fyrefly- 105,700 lightyears.

    Why people post misinformation when the correct information is right at your fingertips is beyond me. It explains our undisciplined society in a microcosm.
    I'm not sure who you're accusing, but I've certainly not posted any misinformation. Here are two seemingly reliable sources giving figures that don't match what you've said:
    https://web.archive.org/web/20151107013154/http://arxiv.org/abs/1503.00257https://www.aanda.org/articles/aa/full_html/2018/04/aa32880-18/aa32880-18.htmlCould you provide your source for this "correct information", please? I'm very obviously trying to find out more information. That was the purpose of my post. Accusing me of things when I'm just trying to investigate is childish and completely inaccurate.
    Reply
  • JJW
    I think you might be running into two problems with the different info.

    The first problem is rounding, numbers are often rounded for simplicity and that can create varying information.

    The second is, where does the galaxy end? - My understanding is that the edges just kind of fade away, it's not really an abrupt end to the galaxy so this would create the problem of different people defining the edge or end of the galaxy in different ways.

    But I don't have any kind of training in this stuff so this is really just a guess and nothing more, take it if you want it =)
    Reply
  • joebakhos
    I believe that this hypothesis explains why Hoag's object has this shape. Please take a look at this video of a modified gravity hypothesis. This hypothesis would explain Hoag's object. It also explains all the effects now attributed to dark matter and dark energy. It also explains the strange acceleration of Oumuamua, the interstellar asteroid that recently passed through our solar system. Here is the link to the video:

    6ijyYWKqwiIView: https://youtu.be/6ijyYWKqwiI

    If you prefer to read, you may download a pdf explanation of the hypothesis here:

    https://redd.it/ao8vfo
    Reply
  • Runesmith
    joebakhos said:
    I believe that this hypothesis explains why Hoag's object has this shape. Please take a look at this video of a modified gravity hypothesis. This hypothesis would explain Hoag's object. It also explains all the effects now attributed to dark matter and dark energy. It also explains the strange acceleration of Oumuamua, the interstellar asteroid that recently passed through our solar system. Here is the link to the video:

    6ijyYWKqwiIView: https://youtu.be/6ijyYWKqwiI

    If you prefer to read, you may download a pdf explanation of the hypothesis here:

    https://redd.it/ao8vfo

    Well, if some guy on YouTube says so, it really must be true. /s

    Gravity as a wave function idea is not really new. However, it is loosely defined, and applied to every thing that lacks enough observations to explain (case in point - Oumuamua acceleration), which lends it a certain "snake oil" quality.

    I do have my doubts about dark matter and dark energy hypotheses, which sound like the ether explanation at the turn of last century (an invented medium to match observations). However, no one has come up with any other hypothesis that matches the current observations and is testable.
    Reply
  • joebakhos
    Well, please take a look first. "Wave function" is a vague phrase. I believe the dampened wave function I describe is indeed new. Also, the hypothesis described is eminently testable.
    Reply