Actually, we don’t know for sure – no more than a bacteria deep inside your belly knows your hair color or shoe size. But unlike bacteria, human astronomers have high-tech sensors and space telescopes. We can measure the distances and densities of star clusters and peer through dense nebulae to the galaxy’s core. By comparing these findings with images of distant galaxies, we get a good idea of our home galaxy’s structure.
Several different telescopes, both on the ground and in space, have taken images of the disk of the Milky Way by taking a series of pictures in different directions – a bit like taking a panoramic picture with your camera or phone. The concentration of stars in a band adds to the evidence that the Milky Way is a spiral galaxy. If we lived in an elliptical galaxy, we would see the stars of our galaxy spread out all around the sky, not in a single band.
Picture Credit : Google