OP, they look through telescopes and figure out how far away the stars are. They record it in a little diagram on a computer and eventually they get a good idea of what it looks like from the outside.
Epic Spaceman made a video about it where he showed how it looks from an outside perspective and our point of view while explaining a bunch of other things.
Wow. Amazing. Like what kind of an answer is “if you’re inside a car you can see the car”. This doesn’t answer a damned thing!
We don’t “know” what kind of galaxy we are in because we’ve never seen it from the outside. That would be impossible with our current technology.
Instead we have made very smart evidence-based assumptions as to how our galaxy looks.
What we know is that we are definitely in a galaxy because the general structure of the universe precludes such a conclusion. The extreme vast majority of matter is condensed in structures that are very uniform, we call them galaxies, therefore we must also be in one.
On a very clear night in certain parts of the world we are able to see in the sky a large elongated collection of stars which the ancients called the Milky Way because it resembles milk flowing down a smooth surface or something along those lines. What we currently believe is that that elongated formation of stars is an arm of one of the spirals that comprises our galaxy. We are also able to look at other structures using telescopes in our galaxy for example we have determined that we have a supermassive black hole in the center as many other spiral galaxies do as well.
So to answer your question we cannot see the Milky Way galaxy as a whole only certain parts of it and we’ve been able to draw conclusions by seeing other galaxies.
All the other comments here making neurotic epitaphs and idiotic analogies about how seeing something from the inside is the same as seeing something from the outside is just dumb and pompous if you don’t know the answer don’t say anything.
We do know quite well what our galaxy looks like thanks to great advances in astronomy. To use your car analogy, it would be like using “X-ray”technology to map the exterior from the interior and get a reasonably accurate picture of the shape of our car.
Wait we can know what it looks like though. They can plot the distance and position of the stars and then they will have a model of its shape as a point cloud.
The original question is very vague and in general difficult to answer without asking additional questions to clarify so I answered the question in the spirit not in the letter.
The same way as I can see most of my body even though I am inside it. Indeed, without a mirror I cannot check whether I got a drunk tramp stamp tattoo last night, but I can still see most of my body and get a decent idea on the shape it as, especially when comparing with other’s people bodies
Your question needs rewording because as its written right now the answer would be that you just look up at night and all the stars you see, are the milky way.
The English phrase is “missing the forest for the trees”
Not quite the same as chess blindness. Possibly the opposite. It basically means: being unable to see (or ignoring) the bigger picture because you’re too focused on minor individual details
In case you mean pictures like this; upload.wikimedia.org/…/Milky_Way_Galaxy.jpg - they are not actually images of the Milky Way. As you’ve guessed, we can’t directly see it in its full spirally goodness from the inside. Instead, these pictures are either artist’s impressions based on scientific understanding, or pictures of different galaxies that are reckoned to be pretty similar to the Milky Way.
Though someday we may find a gigantic space mirror that allows us to see our own galaxy by zooming in on it enough.
The space mirror will be formed by some weird gravitational pattern that happens to send light back the way it came. Not like literal glass floating in space. Just some kind of optical distortion that acts as a mirror.
But we’ll be looking at our galaxy a long time ago.
Over 26000 years ago if the mirror was placed at the very edge of the milky way. I wonder how many light years away the mirror would have to be to fit the whole image of the galaxy inside it.
I just can’t even begin to get my head around those numbers, I am a tiny insignificant ant.