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I am enjoying Orion high in the sky this winter as always. I wondered if I could travel beyond it, say 2730 light years* and turn around, would I see Orion in reverse? If so, what of the neighboring constellations. I know brightnesses would be different but would I recognize the shape?

Happy new year to all.

  • I chose this number because Alnilam is 1360 light years away so I doubled the distance.

Source: https://www.space.com/3380-constellations.html

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    $\begingroup$ Download the open source software "Celestia" and try it I think the answer is no, because the main bright stars in Orion are at different distances. $\endgroup$ – Rob Jeffries Jan 1 '18 at 10:01
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    $\begingroup$ In addition to changing brightnesses and getting a mirror image, you would add the Sun plus whatever stars are directly opposite in the sky to the constellation. $\endgroup$ – eshaya Jan 2 '18 at 0:58
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    $\begingroup$ You'd better travel really really fast, since all the stars are moving relative to each other, and even from Earth some constellations will "fall apart" in a short time, cosmologically speaking. $\endgroup$ – Carl Witthoft Jan 2 '18 at 16:10
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If the stars are all similar distance from us, like the Pleiades, then yes, you could find a place from where the stars would appear in a similar pattern and brightness, but the pattern would be a mirror image.

You can't do it when the stars are significantly different distances because they wouldn't look the same. Most constellations are a range of distances, which wouldn't look like a mirror image from any distance.

Take Canis Major for example. Sirius is the brightest star in the sky but in large part because it's only 8 light years away. The 2nd brightest star in that constellation, Epsilon Canis Majoris is about 430 light years away. At that distance, Sirius might not even be visible to the human eye. It certainly wouldn't be constellation worthy.

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    $\begingroup$ Good example. Sirius seen from 430 ly would have an apparent magnitude of 7.02. The normal limit for the naked eye is around 6.5, so Sirius would be too faint to see. $\endgroup$ – Chappo Jan 2 '18 at 2:13
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As others have said, Orion (and other constellations) only looks the way it does from a specific angle. The stars are distributed at different distances from Earth, so from a different position, including directly "behind" it, it would look quite different.

Here is a (terrestrial) example of something that looks different depending on the angle that it's viewed from (sidewalk "trompe l'oeil" art is popular in some cities). There's only one position where it has the intended effect; even from the same angle, being closer or further would break the illusion.

Sidewalk trompe l'oeil art of a snail

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  • $\begingroup$ Great visual explanation. And really cool pic. $\endgroup$ – Itumac Feb 20 '18 at 3:42
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It depends on if the stars in the constellation are lined up, on a plane or on a sphere. If they line up as a plane, traveling the distance you are from the plane, to the other side, it should look reversed. However, if its lined up on a sphere, it may look distorted, how the inside of a sphere looks to the outside. And if the distances vary enough, it might look somewhere in between or distorted in another way. Typically the distances vary greatly. Heres a nice picture of the kinds of distortion (note that stars almost never line up in any way, distance-wise, in constellations, so this is just mainly for the general idea): Link

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Pack orion in a cuboid of custom dimensions & make sure maximum number of stars touching the faces of cuboid from inside. Make a normal (perpendicular line from the face) reaching earth and then extend the line to other side of the cuboid such that cuboids centre is the centre for the line. Be careful going to another end ;)

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    $\begingroup$ As the other answer shows, this won't work. $\endgroup$ – Carl Witthoft Jan 2 '18 at 16:11

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