There are several types of galaxies: 1. Elliptical galaxies have a spheroid shape with no defined axis of rotation and are classified on a scale from perfectly circular (E0) to flattened (E7). 2. Spiral galaxies have a central bulge, disk, and halo, with older stars in the bulge and spiral arms in the disk. 3. S0 or lenticular galaxies have a bulge and thin disk like a spiral galaxy but no spiral structure. 4. Irregular galaxies have no regular shape and come in two types - Irr I with HII regions and young stars, and Irr II with more dust obscuring stars.

1. GALAXIES By Sara Kowdley

2. Elliptical galaxies [1]are spheroid-shaped. We can see only 2 of 3 dimensions of them from earth, so they look like elliptical disks. They have no particular axis of rotation. There is a complicated classification system within it. The galaxy could be ranked from E0 – E7, E0 being perfectly circular and E7 being flattened. ELLIPTICAL

3. Elliptical galaxy photos:

5. Spiral Galaxies [2] are made up of 3 main parts – the nucleus/bulge, disk, and the halo. The bulge, in the center of the galaxy, is spherical and contains older stars. SPIRAL

6. Spiral galaxy photos:

8. See how these are more tightly wound?

10. S0 Galaxies [3], also called Lenticular galaxies, are between an E7 and a “true” spiral SA. They are different than elliptical galaxies because they have a bulge AND thin disk, yet NO spiral structure of any kind. S0 GALAXIES

11. S0 galaxy photos:

12. Irregular Galaxies [4] have no regular or symmetrical structure. The two types are IrrI and IrrII. Irr type 1 have HII (elemental hydrogen gas and young hot stars) regions, whereas Irr type 2 galaxies have large amounts of dust that block starlight, making it hard to distinguish stars. IRREGULAR

13. Irregular Galaxy Photos:

14. All Done! Goodbye ! Au revoir ! Sayonara! Adios! Zaijian! Ciao! Farewell! Peace out!