This inverse, visible light image shows a spiral galaxy, NGC 784, from the side; astronomers call the view ΓÇ£edge-on.ΓÇ¥ The disk is fairly even and there is no prominent bulge in the center. NGC 784 might look like NGC 6946 if we were to see it from another angle. As the image demonstrates, spiral galaxies are flattened by their rotation. They are thin because they are rotating. This one is about 6.6 arc seconds long but only 1.5 arc seconds thick.
Although this image shows mostly stars, spiral galaxies contain large amounts of neutral hydrogen gas (see radio images) and colder, molecular gas that is gathered into clouds such as NGC 2024.
