How do we know the shape of our Galaxy?
An actual image of the Milky Way cannot be taken simply because we live inside of it and can not(at least for now) go outside of it to image it. If you ever tour the countryside in Eastern or Mediterranean countries, you can see a diffused band of stars(an amazing sight). Galileo in the 17th century pointed a telescope towards a diffused band of Milky Way and saw different stars emitting light and moving across the sky. He showed that the Sun is not the center of the universe as was believed. Now comes 18th century where two astronomers proposed that the structure of Milky Way was circular with stars going around the central region. They also theorized the idea that bright objects(which were then referred to as nebulas) we're another universe (it was believed that Milky Way was an infinitely big universe). In 1785, William Herschel did the first attempt to map the Milky Way. In the 19th century, using better telescopes astronomers further rectified William Herschel's map. But t
