Explain the structure and classification of gal... - SS1 Physics Space Physics and Astronomy Question

Galaxies are large systems of stars, gas, and dust held together by gravity. They come in various shapes and sizes. The main types of galaxies are spiral, elliptical, and irregular. Spiral galaxies, like our Milky Way, have a distinct spiral structure with a central bulge and arms that extend outwards. They contain young stars, dust, and gas. Elliptical galaxies are more rounded and lack the spiral arms. They consist mainly of old stars and have less gas and dust. Irregular galaxies do not have a regular shape and can be chaotic in appearance. They often contain young stars and exhibit ongoing star formation activity.