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I am making a story of a species who lives on a planet several light-years above the Galactic Bulge. With advanced technology, how much could they see from their vantage point? Could they carry out advanced surveillance on much of the galaxy's stars? If not, what would the night sky look like there, assuming the orbital plane was the same as the galactic disk?

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    $\begingroup$ If they are "just above" the chances of them envolving is slim due to the increased frequency of unpleasantly energetic events like supernovae being likely to sterilise their world. They'd have to be quite far above, on a highly inclined orbit about the galactic centre. $\endgroup$ – Starfish Prime Nov 15 '19 at 14:58
  • $\begingroup$ @StarfishPrime Fixed this. I said "just above as if it were a small model. $\endgroup$ – Greenie E. - Reinstate Monica Nov 15 '19 at 15:00
  • $\begingroup$ Doesn't look fixed yet. $\endgroup$ – user535733 Nov 15 '19 at 15:16
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    $\begingroup$ "Several light-years" is pretty small when it comes to the galactic disk. . . The mean distance between stars is about 3-4 light-years in the Milky Way, and the disk is about 500-1000 light-years thick. This planet wouldn't really be significantly outside the bulge at all. $\endgroup$ – HDE 226868 Nov 15 '19 at 15:50
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I'll start with the easy part, they would see two distinct hemispheres of the sky where in one half the Milky Way fills the sky with thousands of visible stars like what we see, and the other half is absolute blackness to the naked eye. The galactic "hub" would appear as a very dense splatter of stars, and the four spiral arms of the milky way may show as streaks in the sky as the milky way itself does to us. This depends on how close you are - like, what "a few light years" means here. Since this is along the same orbital plane as the Milky Way, I will arbitrarily assume your planet had a normal evolution and rotates on an axis nearly perpendicular to the orbital plane. In this case, the Northern hemisphere will never see any stars at all, unless another rogue like your own has spun out there ahead of you. The Southern hemisphere is where all your naked-eye celestial observations would come from. The galactic bulge would be directly above your South pole.

It's interesting to note that in such a world celestial navigation would never have evolved in the Northern hemisphere, and you would likely see much more primitive development in the North as compared to the South. Lands to the North would be shrouded in mystery as they would be almost impossible to navigate until some Southern hemisphere culture develops technology-based navigation such as radio. It would be a confusing and undesirable region to live in, natives of the North would be survivors skilled at orienteering to get around. The night sky has inspired curiosity for millennia and it is the direct fuel for our intellectual advancements.

Observing the galaxy would be no different for them than it is for us. Perhaps they could have a greater resolution in locating stars than we have because they could have better stellar parallax reference points. In that sense, this highly polarized planet could have a slight advantage in surveillance of the galaxy, whatever that really means.

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Assuming that they were exactly where you describe, you would need to find a way of that system surviving past any extinction events involving supernovae and the like.

This could take the form of some kind of field protecting the system. This field would have to use tremendous amounts of energy so either the race that lives there would have to have moved there from somewhere else and constructed some kind of dyson structure around the star of the system or another race had and the race you are talking about just evolved after the builder race had gone (or not).

If their technology was based on our understanding right now, they would probably see distorted images of the rest of the system at best as I would imagine the gravity of the galactic core (lots of supermassive black holes in there) along with whatever energy being deflected by the protective field would probably mess with most conventional methods of observation.
If their technology was more advanced, it is possible that they would have things to scan through all of the interference but the question would be time as the milky way galaxy is over 100,000 light years across and light is the fastest thing we really know.
In practice, this would mean that even if they saw an attack fairly nearby, maybe 10 light years away, by the time they saw it it would be 10 years too late and it would take them longer still to get out there to do anything about it.

I would say the best bet in this situation would be for that central location to be more of a base with FTL ships collecting information and bringing it for analysis.

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  • $\begingroup$ Why is a star outside the main disk of the galaxy more susceptible to supernovae? Our main defense from such is that they have not happened nearby. There's not much defense afforded by other stars. $\endgroup$ – puppetsock Nov 15 '19 at 19:42

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