We can only see ourselves if we look in the mirror or our photos or like we can see how our planet looks because of the satellites . But how can we see our galaxy
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We can see the disk of our galaxy in the night sky…there is a thick band of stars running around us in a circle (that’s where the name “Milky Way” came from). So we know that we’re inside a relatively flat structure. One side also looks thicker and brighter than the opposite side, so we know that one side is toward the center and the other is toward the edge. We can also see other galaxies and infer from them what galaxies tend to look like; ours does not appear to be special.
antithesys’s answer is great. I just want to emphasize that, just as you suspected: **We can’t** see our galaxy. We are inside it, and nothing ever launched by humans has come even close to leaving it. So we have no photos of it, you’d have to be outside for that. Any image you have seen of “The Milky Way” is not a photo, it’s a drawing or computer model of what we think it *must* look like from outside, based on what we can see by looking out in different directions from inside it.
The same way we could draw the shape of a house even if we were trapped inside it. We don’t have any “photos” of it from way outside, but from where we sit we can measure the distance to many many different stars and turn them into a rough map that shows us the shape and size. Then an illustrator or computer draws a pict based on that map
I can draw a map of my subdivision even when I’m inside of it. If I had any artistic talent I could even do a painting of it. Same with the Milky Way, you just map out what stars you can pin down, extrapolate the rest, and hand that map over to an artist to do a rendition of it. Which is what the “overhead” maps of our galaxy are, renditions not photos.
Although we can’t do that accurate of a map of the MW because of the Zone of Avoidance. Essentially we can’t see that far into either the arms and barely at all through the core as dust and other stars block our vision after a fairly short distance in any wavelength but infrared.
Your mirror is a good analogy. Kick up a cloud of dust while looking in that mirror. You will still see yourself and a lot of dust particles. The density of the galaxy is so low that we can see a good percentage of it even though we are in it. We can calculate where these things are and where they are going accurately enough to build a model of it. It may be easier to grasp if you think about the solar system. We are also within that but have a very good idea of what it looks like.
It is constructed from measurements. As long as one observes many stars and can measure their distance and angle from (say) the earth’s viewpoint, it is a matter of geometry to place them on a 3D map. With software, this map can be rotated etc so we get a “constructed” view of the galaxy.
A lot of answers here seem to forget that we can see other spiral galaxies … everywhere. So we’re starting with a very strong hypothesis of roughly what it should look like. There are details to work out of course (e.g., how many spiral arms, density gradients, etc.), but being able to see other galaxies is a real strong clue
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