The galaxies come in many forms and have different shapes. We distinguish three basic types of galaxies due to their shape: Spiral, Barred spiral and Elliptical. Edwin Hubble divided them in this way in 1926. In later years, two additional categories were introduced: Lenticular and Irregular galaxies.

As much as 75% of the galaxies we know are spiral galaxies. Their sizes are very large and range from 15 to 150 thousand light-years in diameter. The mass of spiral galaxies ranges from 10 billion to 10 trillion masses of the Sun. In spiral galaxies, most of the mass focuses in the center, gradually reducing the density towards the spiral arms. Looking from the side of such a galaxy, we see a central bulge and a thin disk that can contain all kinds of nebulae, globular clusters or areas of dark dust on the entire surface. Young bright stars usually appear in spiral arms. The core of the spiral galaxy is dominated by old and red supergiants. An example of a typical spiral galaxy is our Milky Way and Andromeda galaxy (M31). Spiral galaxies probably formed longer than elliptical. The types of shapes of this type of galaxies suggest numerous cosmic collisions with other galaxies. The example in the picture next to shows the collision of spiral galaxies. Barred spiral galaxies are much less common. The bar is made of bright stars and hot gases around the nucleus.

They are huge balls made of stars. Some have a somewhat flattened shape. The largest of them have a diameter of 100,000 light years, and the mass sometimes reaches up to 100 trillion masses of the Sun. This is because matter in such objects is much more densely focused than in spiral galaxies, in which similarly is only in their very core. However, large elliptical galaxies are rare. Most of these types of objects are small galaxies up to 1000 light-years in diameter. Scientists believe that elliptical galaxies arose a long time ago in the still-young universe. These objects contain mainly older stars and have a small amount of dust compared to spiral galaxies.

Between spiral and elliptical galaxies there are objects on the border between these two classes. They don't have spiral arms and usually consist of old stars. Like elliptical galaxies, lenticular galaxies don't contain too much dust, sometimes they collect only along the edge of these objects. Irregular galaxies don't have specific typical shapes. They are similar in shape to clouds similar to nebulae. There are relatively few of them. The two most familiar and closest to us are the Large and Small Magellanic Clouds. Unfortunately, they are visible only in the southern hemisphere of Earth's sky.