Would a galaxy be visible from outside, but nearby?

I am very deliberately not illustrating this answer with an image, because essentially any photographic image will misrepresent what you can see in the sky with the naked eye.

The surface brightness, that is the light per unit angular area, of extended objects is independent of distance$^1$. This is because the angle subtended by an object is proportional to the square of its distance, and so is the amount of light reaching an observer.

In other words, a galaxy looks about the same at any distance: it gets bigger or smaller, but its surface brightness (and therefore contrast with the background sky) doesn't change. This breaks down once you get close enough to pick out the individual stars, but with the naked eye you need to be just about inside the galaxy for that to happen$^2$.

Now the answer should be obvious: you would never see a galaxy looking like the one in your Star Wars screenshot. Rather, it would look like other galaxies you can see in the sky. If you've been to the Southern hemisphere and seen the Magellenic Clouds, you have a good idea of what another galaxy looks like with the naked eye. Likewise if you've managed to pick out Andromeda from somewhere dark. Actually, the fuzzy band of our own Milky Way also gives a decent idea of how bright on the sky a galaxy would look from outside$^3$.


$^1$ This isn't true for really distant objects when cosmological surface brightness dimming starts to kick in, but that isn't the case here.

$^2$ You could pick out some individual very bright stars from further away, but the majority that make up the smooth looking light of the galaxy start to blend together pretty quickly with distance.

$^3$ Because we're inside the galactic disc there's a lot of dust to get in the way of the view which causes some dimming, but it still gives a decent idea.


Standing one or two light-years would never do it. Length of our Galaxy is about 100,000 light years. In the shown picture, the visual angle would be about 15°. Do the math, they're about 380,000 light-years away from our Galaxy.


From NASA:

enter image description here Explanation: The Great Spiral Galaxy in Andromeda (aka M31), a mere 2.5 million light-years distant, is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface brightness is so low, casual skygazers can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda, tracing beautiful blue star clusters in spiral arms far beyond the bright yellow core, is combined with a typical view of a nearly full Moon. Shown at the same angular scale, the Moon covers about 1/2 degree on the sky, while the galaxy is clearly several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 and M110 (bottom).