(Originais Teachy 2023) - Question Medium of Physics

The universe is composed of a vast amount of galaxies, which are groupings of billions of stars, gases, and dust interconnected by the force of gravity. Galaxies can be classified into three main types: elliptical, spiral, and irregular. The Milky Way, our galaxy, is an example of a spiral galaxy. Considering this information, answer: (a) Describe the main characteristics and differences between the three types of galaxies mentioned; (b) Explain why the Milky Way is classified as a spiral galaxy; (c) Differentiate a galaxy from other celestial bodies, such as black holes, nebulae, and stars, in terms of size, composition, and structure.