Tim Daughters asked Neil deGrasse Tyson:

How do we figure out the shape of our own galaxy and where we are in it? It seems like trying to determine the floor plan of a house while being restricted to the bathroom.

Neil deGrasse Tyson Yup. Or harder still, figuring out what your mother looks like while still in her womb. This was a fascinating scientific challenge, spread over many decades in the 20th century.

By noticing that the "Milky Way" on the sky was a band of light, first implied that whatever were in, was flattened. Further, and only with the advent of radio telescope, we identified the locations of immense gas clouds as well as the direction on the sky where the intensity of radio waves peaks. That told us we are in a flattened, gaseous galaxy with a major source of radio waves in one direction and not others.

By analogy to other nearby galaxies in the universe we concluded that we live in a flattened, gas-rich spiral galaxy, actively making stars within one of its spiral arms. Quite the fun detective story. Hundreds of scientists, dozens of telescopes, thousands to research papers.

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